# Insulation help in attic/half story



## swindmill (Apr 14, 2010)

I purchased a 100 year old, recently remodeled home several months ago.  It's a 1.5 story shotgun style house. The second story has a bedroom and a full bathroom.  It has a relatively small unfinished attic space, where I am in the process of adding a walk in closet. I have read many threads on insulation and followed links to outside sources and read those, so I'm in the process of learning what I can about proper insulation, but I still have quite a few questions.

The entire house appears to have been insulated using rolls of fiberglass R-13 and R-19.  As far as I can tell, the exterior walls were done with R13, but there is R19 in random places.  I can't discern if there is a method to where the R-19 is vs. the R-13, but the house is built with a mix of original studs (2x5??) and newer 2x4s. I get the feeling that the insulation job done by the remodelers wasn't stellar, but the half story/attic space is really bad. 

I've gutted the bathroom upstairs and it appears as though the ceiling in the side attic is insulated w/ R-13, and the knee walls aren't insulated at all. The 'ceiling' upstairs is a strip that's about 1 foot across ( /-\ ). There is recessed lighting there, and the remodelers simply did not insulate at all in the top attic, leaving a large amount of space uninsulated. A side note - there is a large faux vent on one wall that simply leads to the side attic...maybe someone can explain that, or tell me it needs to be filled.  Another observation I had is that there is no insulation on the "floor" of the side attic, above the downstairs ceiling.

The unfinished area in the attic has loose insulation between the floor joists, but it can't be much more than 5" deep.  There is no insulation between the ceiling joists.  It doesn't appear as though the soffits are vented.  There is one gable vent.  I am in the process of adding a ~4x8 closet in this space, leaving side attic space on either side and about 3 ft. between the back wall of the closet and the front of the house (where the gable vent is).  

After all that description, my question is what steps do I need to take in order to correct the existing insulation and how do I best insulate the unfinished space as I build the closet? It gets very hot upstairs while the downstairs stays very comfortable.  Money is an issue, so if I can do this myself it would be preferable.  The biggest issues I see are insulating the top attic without tearing down drywall and without getting near the recessed fixtures.  I hope my description makes sense and thanks for reading through all of this.  Any thoughts or advice concerning how to go about this and what type(s) of insulation to use are greatly appreciated.


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## AU_Prospector (Apr 15, 2010)

Hey it looks like u have some work to do.  My limited knowledge says three things from your post.
1)  All your attic space, that is your interior ceilings (ALL) should be insulated to R38.  Two layers of R19 will do it.  First layer faced on the bottom, second layer unfaced.  I think thats around 18 inches minimum if you use blown in fiberglass. 
2)  You cant have enough ventilation in your attic.  You need to add some.  Soffits are a must, Gable is good, the more the better.  Maybe add an attic/roof fan to pull air up through your soffits and out your roof or they make them for gables too.
3)  Dont block any flow of ventilation.   If your closet project cuts your attic in half and blocks the flow of air, you should vent both halves adequately.  Dont leave the other half unvented. 

Personally I dont have enough insulation either so I have work as well.  But my vents are good.  I have a weird roofline with vents at each gable (5 vents).  I also have two electric roof fans that click on at higher temps.  I have ridge vents cut into the tops of my rooflines.  Also my soffits are vinyl and perforated for ventilation.  I am also careful not to block airflow from the soffits up to the crest of my attic.  If I stand in my attic with all the lights off, I can see light all around me from the gables to the soffits.  On a windy day its breezy in my attic.  I think that is good.


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## swindmill (Apr 15, 2010)

If I already have fiberglass rolls between the the roof and the drywall, is it possible to have more insulation blown in without tearing down all the drywall?  
Also, I'm not mistaken in thinking that I'm limited in R value by the space available between the roof and drywall? Because ceiling height is obviously an issue in a finished attic, I can't feasibly lower the ceiling even if I went to the length of tearing out the drywall.

I have to look closer at my soffits to see why they aren't vented, or what's in the way.  The outside of the house is newer vinyl siding over the old wood.  I know the soffits are perforated on the outside, but something must be blocking them on the other side.


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## Perry525 (Apr 15, 2010)

A bathroom needs to be comfortable not too hot or too cold and as a bathroom creates a lot of water vapour it need to be ventilated.
I recommend that you do this job properly as water vapour can lead to wood rot.
You need to tear down the drywall.
And fit polystyrene or Blue Board between the framing, pack in at least four inches thick, and it needs to be a tight fit, between the rafters.  No gaps or cracks.
Cutting it with a knife works OK, a saw makes even more mess.
Then fit a plastic water proof sheet over the framing taking care to overlap the joints and seal them.
This is to ensure that none of the water vapour gets into the wall/wood and starts rot.

Then fix another two inch thick layer of polystyrene over the plastic and finish with drywall. This last layer is to prevent the heat from the bathroom escaping by conduction through the wood, and it stops the heat from the sun coming in.

 A temperature of 51C/124f on one side of a two inch thick piece of polystyrene will often result on a temperature of 38C/102f on the other, so you can see six inches of polystyrene should meet your requirements, with a drop to about 22C/70f.

It makes sense to do the whole attic to the same standard.

Then fit an extractor fan, one with an automatic shutter to keep out the wind and a built in humidistat that will turn it on as required.


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## swindmill (Apr 15, 2010)

Tearing down the drywall in the bathroom wouldn't be a huge job, and I think I probably should.  The Blue Board idea is a good one, although I'm not sure I'll have two inches to spare outside the rafters.  Maybe five inches would be enough.  What about spray foam? I understand that it has a pretty high R value per inch.  There is a fan above where the shower will be that vents directly into a roof vent above the bathroom. Perhaps that helps with the rotting concern.

As far as the rest of the attic, it is quite a large space and replacing all of the drywall would be a big job for me, and certainly put me past the time period in which I was planning to finish the upstairs.  If there is no good alternative, then I have to do what I have to do, I suppose. I will probably live in this house for 4-5 years, so not too long relatively speaking.

The part that I am finishing will obviously be done correctly from the start, but I need to figure out what correct, or even perfect, is for this situation.


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## AU_Prospector (Apr 15, 2010)

can you add pictures?  That would help


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## swindmill (Apr 15, 2010)

Here's one of the bedroom and unfinished portion of the attic where the closet will be. I'll add better pictures, including the bathroom, later on today.  Thanks for the help.














The wall between the unfinished and finished space (not pictured from unfinished side) is not insulated.  There was an old chimney there, which I removed in order to put a closet entry way in.  I'm hoping that correcting that will make a big difference.


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## Perry525 (Apr 15, 2010)

I accept that space upstairs is always tight.
I am sure that except on the hottest days and coldest nights 5 inches will be fine.

Spray foam is the best insulation (available) as it fits into every space and leaves no cracks for the air to be pulled through.
However, while it is quick and easy to apply, if you are on a budget you will find it very expensive.

The fan above the shower, venting into a roof vent is fine, if you can buy a humidistat to fit on to it....that's good enough.

The thing with fans is they need to pull the air from somewhere, so they can blow out the steam. Is there an vent for the air to come in?

Sorting a home and making it air tight and bringing the insulation up to date, when you are working, does take a long time. Best to do a bit when ever you feel like it.

Do keep in mind that there are millions of homes that are poorly insulated, badly ventilated and suffering  damp and mould in twelve or so different States.


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## swindmill (Apr 15, 2010)

Bathroom:









You can see how the upstairs is likely insulated throughout from these pictures of the bathroom.  The knee walls are not insulated, but the roof is, at least until it gets near the top attic space where it stops.


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## Perry525 (Apr 16, 2010)

I afraid the pictures say it all, the insulation is just not good enough by today's standards.
Where we are all trying to keep our heating and cooling costs down.
One really needs a bathroom to be comfortable, not too hot, not too cold, and cheap to run.
And R13 just doesn't do it.
Not only is the insulation poor, it totally ignores the heat loss/gain through the framing.
With six inches of polystyrene or Styrofoam, you have a situation where for most of the year the bathroom will be comfortable without adding extra heat or using the air conditioning.
Done once and done right, it will continue saving money for a lifetime, for you and subsequent owners.


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## swindmill (Apr 16, 2010)

Bathroom: You've definitely talked me into tearing out the rest of the drywall and starting over with insulation.  I'm guessing I'll need to put some sort of stop (drywall, plywood) behind the framing of the knee wall so that I can put polystyrene there as well. I'll do at least 5 inches, 6 if feasible, along the knee wall, sloped ceiling, and top attic so the room is completely incased in it. I'll have to work around the recessed lighting and fan of course.

Closet: Should I do the same thing with the closet? Incase the room in 6 inches of polystyrene? I could then just add lose insulation to the area of the attic that remains unfinished and vent it properly.

Bedroom: While I'm a big fan of doing things right, I just can't tear down all that drywall and have to rehang, refinish, and repaint that entire space.  I'm thinking about having an insulation company come out and look into blowing additional insulation in behind those walls and into the top attic.  Doing that (if it's possible?) along with properly insulating the closet and unfinished attic space would be a big improvement, I would think.


If I'm going to do the foam board in the bathroom and closet, would it make sense to have a spray foam contractor come out and spray foam those two rooms, or would that be a lot more expensive than doing the boards myself?  Thanks for the help.


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## Perry525 (Apr 17, 2010)

If you cut the foam as a push tight fit, then it will stay in place without any backing.

Yes the idea is to have a complete polystyrene box, that is both air and water vapour tight.

With the lights and fan, use some cans of spray, to keep the total integrity.

Keep in mind,  for the fan to do its job it needs  to pull air from somewhere, so that it is pushed outside with the water vapour.
If there is no air supply the fan will struggle to clear the room.  I normally suggest that an extractor fan with a heat exchanger be used as you get a balanced flow, with the incoming air being warmed by the extracted air.....but, in your case venting through the roof...it may not be possible.

Yes. The problem with water vapour (that which is not expelled by the fan) is that it always makes for the coldest spot to condense, these spots are the toilet cistern, the windows and any spots like the closet, where there is no warm air circulating. Result, damp, mould, wood rot, smells. Not good.

Finish the bathroom and closet, see how it goes through the summer, then think about the rest of the job and decide when you are sure.

The spray foam, you can do it yourself, and will probably take more care and do a better job.(and it will be cheaper) Ask around you may  find a good price, watch out for a cheap price and someone who doesn't do the job properly.
If you do get someone in, stand there and watch them do the job, do not go away and leave them to it. After all its your money and you have to live with the result.


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## swindmill (Apr 19, 2010)

Thanks for the advice. I'm going to look into the spray foam option and weigh it against the Polystyrene option.  I'll do one of the two in the next month or so.  Waiting on the bedroom is a good idea. Hopefully it will feel better with the closet and bathroom done.


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## Perry525 (Apr 20, 2010)

May I add one more recommendation.
Buy an infrared temperature gauge.
With this you can hold the trigger and scan anything and it will tell you its surface temperature.
Use it to measure the temperature of the walls in the bathroom and closet after you have finished.
Then read the temperatures of the rest of the attic that are "as now."
This will show you what you have achieved and what remains to be done.


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## swindmill (May 25, 2010)

The closet mentioned above is framed in and ready for insulation.  I'm still debating on what exactly to do to keep it cooler up there.  The roof joists are about 5" deep and 24" apart. From reading up on this issue, I'm led to believe that I really need a radiant barrier against the actual roof, before putting in insulation.  Is this true?

If so, based on cost and limited space, I'm thinking about doing the ceiling of the closet in this order:  roof|radiant barrier|R-19|3/4" polystyrene board over the joists|drywall

That'll give me R-23 plus the radiant barrier, which isn't great but unless I give up ceiling height it seems to be about the best I can do, taking cost into account. 

My main objective is to combat the extreme heat upstairs.  Since knocking the wall out for the closet, it's so incredibly hot up there that I literally start sweating within 30 seconds of walking up the stairs.


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## Perry525 (May 26, 2010)

Fix two layers of 2 inch thick polystyrene between the rafters. With staggered close fitting joints. Cut them to a push tight fit.
Two inch thick is easy to cut with a knife.
If you go for one  four inch thick layer cutting with and old saw will be easier, but more messy.
Stick a radiant barrier on the top sheets, carefully leaving a one inch gap between the top of the polystyrene/radiant barrier and the underneath of the roof, this will enable the radiant barrier to reflect the suns radiation back up through the roof.
The polystyrene between the rafters, will stop the hot convection currents transmitting the heat from the roof through to the drywall.
Then fix another layer of polystyrene across the rafters, this will stop the conducted heat that arrives in the room via the, roof and the wooden rafters.
Then fix the drywall screwing through the drywall/polystyrene into the rafters. 
The result, a one inch gap, a reflective layer, five inches of polystyrene, one layer of drywall.


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## swindmill (May 26, 2010)

I noticed that Lowe's sells a polystyrene board with a radiant barrier affixed to each side of the foam.  I think it's called "perma-R" or something similar.  Could I use that in place of the radiant barrier and first polystyrene board?

The old roof joists are all about 4 inches deep.  They are not consistent in depth (and so not level), and 4 inches isn't deep enough, so I'll have to sister something to the inside of each joist.  I imagine any gaps or cracks this creates can be addressed with a can foam insulation.

Is there any need for a vapor barrier on the outside of all of this?

One last question: Should I insulate the attic ceiling all the way down to where it meets the floor, and insulate the knee wall.  Or, should I only insulate the knee wall?  It is a 100 year old home and does not have soffit venting. It has only one gable vent, which really doesn't do much of anything.  The space left unfinished is really just the side attic behind the knee walls.  Should I just go ahead and insulate everything rather than worry about how to properly ventilate the little space that remains?


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## Perry525 (May 27, 2010)

By all means use a board with a radiant barrier on both sides, only the side facing the sun will reflect the suns radiation.

Five inches of polystyrene will reduce an outside temperature of 95f to about 74f on the inside.
Yes blocking all gaps does make a difference. As I mentioned earlier once a convection current starts up it can move an incredible amount of heat from one side to the other. Foam is ideal for filling odd shaped holes.
The purpose of an vapour barrier is to stop the water vapour created inside the home, by cooking, washing and breathing getting into the walls and rotting the wood. A vapour barrier is always positioned under the drywall.
Polystyrene is windproof and waterproof (in as much as continuous immersion in water will result in a 3 to 4% take up of water) In your location, the fact that it is warm, makes polystyrene a useful vapour barrier. (Provided there are no holes)
Yes, to get the maximum benefit of your work, the whole room should be protected by at least five inches of polystyrene.

Keep in mind that the heat that will arrive inside the room, will mainly come by conduction via the roof, rafters and the small amount of polystyrene covering the rafters. If you measure the length of the framing to the room, the width and the total amount of square feet of wood covered by your proposed 3/4 inch polystyrene and divide that into the total square footage of the ceiling and walls, you will be surprised how large this weak area is, and what an impact it will have on the rooms temperature.

One inch of polystyrene with a temperature on one side of 126f will show about 98f on the other, from this you can see that the wood of the rafters will end up being the weak link,  two inches as a cover  of polystyrene is better.

The purpose of roof ventilation is based on an incorrect premiss.

The theory is that the wind blowing over a home will create an area of low pressure to the lee of the home. This will then suck the air from the attic and remove any water vapour that has infiltrated from the home below.
 This will remove the likelihood of ice forming during the winter.
The fact is there are many days/nights when there is no wind.

 During the summer, the theory is, the wind will remove the heat from the attic. 
When on many days there is no wind. And in any event the heat is transmitted via conduction through the framing and radiation.

So yes! The more and thicker the insulation, the less heat will get through to the room.

If you have south facing windows, then an outside shutter, will be a great benefit, shading the room and keeping the radiation out.


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## swindmill (May 27, 2010)

Then I'll plan on insulating the entire space, finished and unfinished, and then insulating the knee walls as well.  I was going to change my plans a bit to include sistering 2x6's to the ceiling joists so that I have 5.5" of space for insulation.  If I were to do that, I wouldn't have enough room to also put 2" of polystyrene on the outside of the 2x6's.  2x4's provide slightly less depth than the existing joists.  So, I'd have to come up with some combination of material that puts the depth at 4.5".  I'm thinking I could put a 1/2" polystyrene board with the radiant barrier in and then the 2x4 on top of that...but that just seems a bit unconventional.  The bottom line is that 5.5" of insulation is about as much as I can do before putting up the drywall, otherwise I will be sacrificing too much head space, which is very limited as it is.


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## Perry525 (May 28, 2010)

The only time you can get a job 100% right is with a new build.
Renovation is always about compromise.


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## swindmill (Jun 11, 2010)

I ended up sistering 2x4's to the existing ceiling joists, spacing them 1.5" from the ceiling boards.  I then placed 24" wide strips of Reflectix between the joists and above the 2/4s, with the idea being that it would sit 1" - 1.5" from the ceiling boards.  Over the Reflectix, I had room for R13 bats, which I stapled in place.  The knee walls and end walls are insulated with R19 bats. I realize the Reflectix and R13 isn't enough insulation for a sloped ceiling, so next I'll add polystyrene board to the entire room.  All of the unfinished area, including the front gable wall and the sloped ceilling in the side attic is insulated with R13 bats...not much, but it's all the joists/studs would allow, and it is unfinished (I did seal off the only vent I had (gable) because it's such a small area and it's now insulated).  

I have IC rated recessed fixtures in, and I noticed yesterday that they are hot to the touch.  I do need more insulation in the top attic area before putting up the polystyrene.  The Reflectix and the R13 bats meet at the ridge, but there's obviously a gap there.  I'm thinking about laying a 16" bat up there (that's about how wide it is) and then stapling a strip of Reflectix below that.

The bottom line is, it's still HOT in the room, but I still have the polystyrene and drywall to go.  If anything I've laid out above is clearly wrong, please advise and I'll correct it before continuing.  Thanks for the help so far.


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## Perry525 (Jun 11, 2010)

May I suggest that you buy an infrared temperature gun.This will enable you to measure the outside temperature of your roof from the ground  and to scan the inside of the roof to see what you  have achieved.
You can scan the parts you have completed and compare them with the part that remains to be insulated. 

This will enable you to compare the early morning temperatures inside before the sun gets going. With say mid afternoon when it is really hot.

These temperature guns are really handy, they will indicate the surface temperature of anything you point them at.

Get close for a small area, like the room side of the roof between the rafters where you have placed your insulation and the room side of the roof where it is fixed to the rafter and where you have the maximum conducted heat.

Bats only really work when they are sealed in a plastic bag or an airtight box - the problem with them is that the warm air moves through them and round them, and  worse still they cannot be fixed between the joists or rafters to ensure an airtight seal. Add to that they are transparent to water vapour, that easily passes through on its way to landing on the nearest cold surface, leaving the possibility of mould and wet rot.

The reflective membrane is supposed to be positioned an inch below the inside of the roof, to enable the radiation from the sun to be reflected back out through the roof. It should be continued down between the rafters until they meet the top of the walls.

Insulation should then be positioned immediately below  the reflective membrane, between the rafters. 

The rafters support the sloping part of the roof.
The joists run horizontally supporting the ground floor. They make the ceiling of the ground floor rooms and the floor of the upstairs.

The knee walls have insulation between the studs.

All of the room sides of the rafters, joists and knee walls should be covered with tightly butted polystyrene, preferably two or more inches thick, to stop the heat moving by conduction through the wood framing, the polystyrene on the ceilings and walls and knee walls is then covered with drywall. The floor with floor boards,  plywood, or oriental board, as you prefer.

Drywall is important! It provides a half hour fire retarder - this will be important should you ever have a fire.

The recommendation for a heat tight, no energy required home in a very cold, or very hot area, is 14 inches of polystyrene. Temperate areas require less, but every year the recommended level of insulation goes up, therefore it is down to you to decide how much.

Where you are five inches of polystyrene will make a large difference but, one has to accept that, there is a play off between what is desirable from an energy saving, and comfort providing point of view and what is possible because of the nature of the building.


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## swindmill (Jun 14, 2010)

I will look into a temp. gun.  If they aren't too expensive, it certainly seems like a nice thing to have.  I would have liked to used 5 + inches of polystyrene, but the cost was too high, and because of the odd spaces and obstacles between the rafters, it would have been very difficult to get a tight fit.

I did get the radiant barrier in there as you described, at least as best I could given the flexible nature of what I used. I imagine it collapsed towards the roof in some places.  It seems that the area that remains hot to the touch is where the rafters meet at the top of the roof. This is obviously also where the radiant barrier and batts meet, leaving a small gap.  The recessed fixtures I've installed there are hot to the touch.  I need to figure out the best way of dealing with this.  

I will put as much polystyrene as I can on the room side of the rafter and studs, taking into account the need for head space. I really hope that when I finish this, the room won't be the sauna that it still is.  I've begun gutting the bathroom upstairs, and I'm now leaning towards ripping out the existing drywall and insulation in the bedroom.  I'm thinking about putting in 2x6's in these two rooms (at least the bedroom, as the floor is lower), and having someone use spray foam insulation.  I really want the bedroom and bathroom to be very comfortable living spaces.


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## Perry525 (Jun 14, 2010)

You can get them from Amazon for under $25.00

Understand, things like this are always a compromise.
Where you have odd shapes to fill, spray foam in a can is a great help.

That's where polystyrene sheets come in, laying or sticking the radiant barrier to the top sheet of polystyrene makes fitting a lot easier.

You can buy a type of plastic can to fit over, this helps to stop the spread of fire.
Then cut a hole in some polystyrene to fit round and over, if you do not insulate the fittings, these will be a weak link, as you write, they do get hot.

Spray foam is the best you can buy, while being expensive, you can buy and use DIY kits thereby saving on paying someone for their time.

Once you have bought the infrared gun, you will see just how hot the different parts of the roof and rafters get. You will see how hot the outside of the roof is and how much of that heat comes in. Then after fitting the polystyrene and radiant barrier between the rafters, you can measure again, to see the amount of heat held back by the polystyrene and the heat coming through the roof and rafters by conduction.
This will enable you to finally decide how thick a layer of polystyrene to fix across the inside of the rafters etc.

In very hot places 14 inches of polystyrene fitted over the roof in a system called SIPS, using a sandwich of polystyrene with Oriental board on both sides, provides a total break between the shingles and the inside of the home, getting rid of  conduction of heat through the framing really works wonders, and as the roof is sealed there is no movement of air by convection. 
Something to work towards when  you can afford it.


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## swindmill (Jun 14, 2010)

Do you think that the radiant barrier and batts, currently in the new room (closet), is doing much at all?  I plan on adding the polystyrene and drywall and moving on to the bathroom and bedroom where I may just pay for someone to spray foam when I have the money.  I've looked into the DIY kits, but they seem to be several thousand dollars.  I'm afraid to discover what someone would charge to come out and do it.


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## Perry525 (Jun 14, 2010)

Dow $400.00 delivered for 16 cubic feet - wild? It will go no where!
Add the cost of someone doing it!!!!

I would think not, the problem is, they allow air and heat to move through and round them, they are a bit of a waste of time, insulation needs to be a tight fit, if hot air can circulate round an object, then it does, and the insulation effect is lost.

DIY is best,  take your time, do it carefully, use cans of spray in the odd corner. 
I am sure you will be pleased with the final job.


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## PatHIverson (Sep 28, 2010)

We are experiencing a similar issue with our house. I would love to see more pictures of the ways you remedied the situation. 

I've read some of this thread and I'll continue later and hopefully contribute. Thanks for the share.

Cheers


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## swindmill (Nov 10, 2010)

My half story has become a much bigger project than I planned when I started this post. For cost reasons, I've put it off for quite a while but I'm getting ready to get going on it.  I'm having a large dormer added in the next month and then I'll be having the entire underside of the roof spray-foamed.  As I've said elsewhere, I have no soffit vents or ridge vents, so I'm having the spray foam directly applied to the underside of the roof.  After all the research I've done and after what I've learned in this thread and elsewhere on this site, I really don't see any other feasible options, and I want the half story to be a comfortable space in 90 degree weather.


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## Perry525 (Nov 12, 2010)

I notice that you do not say how thick the foam will be.
Kindly note that foam shrinks over the first 5 to 10 years by 15%.
This can result in gaps at the top where cold patches develop, leading to condensation and damp during the winter and hot patches during the summer.
This also means that the overall thickness declines and more heat comes in.
You must ensure that you watch the person who sprays the roof, to make sure he lays on the thickness you have paid for.
Do make some discrete marks at the thickness you are paying for, making it easy to check progress.
Note, If you do not ensure the correct amount is sprayed on, you will almost certainly end up with less than paid for.
A lot of these people work on the basis of. Out of sight.....you won't know what they did.

You must also take into account that the rafters in the roof need to be insulated.
The rafters are in direct contact with both the world outside and the air inside the room.
Most heat enters a room from the outside by conduction, the route, roof to rafter, rafter to drywall to air.
You must line the room side of the rafters with at least 2 inch thick polystyrene or similar.
With an outside sun temperature on the roof of 86f you will measure 82f on the inside with a one inch thick layer.

We all have our own idea of comfortable.
Mine is to keep our home around the 72 f all year round.
To achieve this in our bedroom ceilings we have 5 inches of polystyrene, 3 inches between the joists and 2 inches below the joists.
In our sun lounge where we have large windows floor to ceiling on three sides East,South and West, to help make up for this we have ceilings with 8 inches of polyurethane foam, 6 inches between the joists and 2 inches below.
In our lounge and dining rooms we have 7 inches of polystyrene, 4 inches between the joists and 3 inches below.

The above may help you to understand insulation and the effect, large windows, location and orientation have.

As an aside, our bedrooms on one of the hottest days of this year 98f =71f inside.


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## swindmill (Nov 12, 2010)

I appreciate your continued input.  The existing rafters have a depth of 4", but aren't completely even.  I plan on sistering 2x4's 1.5" off the underside of the roof, giving me 5" depth between the rafters.  I could then put polystyrene over the rafters with the 5" of foam above. There are too many imperfections in the "ceiling" to do a really good job using only polystyrene boards, which is why I'm going with spray foam.  I also 3 gable end walls and the dormer that will be spray foamed.

As soon as the dormer is built, I'll be pulling the existing drywall and insulation out myself.  When that's finished, I'll have the spray foam put in, and after that, I'll be putting up new drywall with a friend of mine.  So, I'll have ample opportunity to see the finished product when the spray foam is done.

Let me know what you think.


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## Perry525 (Nov 14, 2010)

That should work.

The remaining weak link will be the new windows.
I solved the problem by having quadruple glazing.

That is, two sets of double glazed windows, with a gap of eight inches between the inner and outer panes of glass, with venetian blinds in between.
This enabled the blinds to  block the direct sunlight while reflecting the light into the room.

In the normal way double glazing with a venetian blind, results in the blind becoming very hot and transferring the heat into the room, the second set of double glazing keeps the heat inside the window recess.

If I ever get round to building a home from scratch, I will copy the Europeans, in France, Germany and Switzerland.
They recognize that the best asset is shade, they nearly all have external roller shutter blinds, these are kept in a box either above or below the window and are wound into place eith by hand or using an electric motor, it is a system that  keeps the heat outside, leaving the double glazed windows cooler in the shade.
They can of course be stopped in any position to allow light into the room.


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## gmicken (Nov 15, 2010)

Have you thought about spray in foam? Have you had a cold drink in a foam cup in the summer and noticed, no sweat? same thing in your walls. I have been getting the spray foam installed instead of fiberglass for a few years now. It will pay for itself, in heating and cooling bills. The last job I did, I was charged $1.55 per sq ft for walls.


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## swindmill (Nov 23, 2010)

Spray foam is what I'll be using.  I got an estimate last Friday.  The cost to do the entire underside of my roof at 5", as well as 2 gable walls and the 10x8 wall that I'll have when I complete the dormer, is $1500. He's going to use open cell on that.  I was surprised at how inexpensive it was.  The same company is going to lay plastic in my crawlspace and spray foam the inside of the foundation with closed cell foam for $600.  I'll have some before and after pictures of the spray foam job, so maybe I'll post them here.
Here's where the roof is going to be cut out and raised, and you can see the pathetic insulation job that the previous renovators did; that's R13. 




Untitled by


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## Perry525 (Nov 24, 2010)

A lot of people seem to believe that laying plastic sheet over the ground in the crawl space will stop the moisture in the ground from rising and condensing on their joists and thereby prevent mold and wood rot.

This seems to be based on the observation that when you lay plastic sheet on the ground and then lift the plastic sheet there is  always condensation on the underneath of the plastic.

The facts are that the temperature in the crawl space is always so low that the air is to all intents dry and the ground is even cooler, the moisture in the ground does not suddenly decide to warm up and project itself upwards onto your woodwork.

Water vapor always moves from warm to cold, therefore it stays where it is. Unless you have large gaps under your home, where freezing air can be sucked under the home by the passing wind. Then moisture will migrate into the freezing air.

The wood  of your floor will always be warmer as a certain amount of the heat in your room escapes downwards by conduction and radiation.

This brings me to the spray foam on the inside of the foundation. What is this supposed to do?

As I have written many times, heat always moves to cold.

When insulating your home, you need to keep the heat inside your comfort zone during the winter and to keep the heat out in the summer.

To make this process as economical as possible, the insulation needs to be as close to the comfort zone as possible.

Therefore, placing insulation on the perimeter of the crawl space will do nothing for you in summer or winter.

Placing the insulation on the room side of the downstairs floor will keep the maximum amount of heat both in during the winter and out during the summer.

However, because of the problems caused by raising the floor level, raising door frames etc. most people settle for having the insulation tightly packed between the joists under the floor. As with your roof, the joists then become the weak link and it is usual to fix two or three inches of polystyrene sheet across the floor to keep the heat inside the joists.

There is no point in allowing even a small amount of your expensive heat to escape through the floor into the proportionally vast crawl space, where it will in all probability not even raise the air temperature by one degree.

May I suggest that you use that infrared temperature gauge to read the floor temperature inside the rooms, then read the under floor temperatures and the bottoms of the joists, then the ground and foundations. Get a real idea of what is involved.


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## swindmill (Nov 24, 2010)

I understand your points, and ideally, I would insulate the room side of the floor, while laying a new subfloor over the original heart pine, and then a new wood floor.  I have plenty of ceiling height and removing baseboard and door jambs doesn't bother me.  The problem is the cost of a new floor.  Incidentally, because my heart pine floor is not level, and jacking it up in the necessary places isn't feasible, I do plan on eventually leveling it on the top side and doing exactly what we're discussing.  That may be some time from now, however.

Right now, my crawlspace is actually a little bit drafty.  I'm hoping to have someone do repair work on the brick foundation, followed by a concrete stucco.  Doing that and sprayfoaming the inside perimeter would at least keep the crawlspace as water and air tight as it practically can be kept.  My HVAC ducts all run in the crawlspace, and my water heater is down there too.  The sprayfoam should at least help in that regard.  

You mentioned that the heat upstairs keeps the joists warm enough to prevent them from being moist.  My understanding is that for this reason, it is not necessarily a good idea to insulate between the joists.  The insulation between the joists will then stop the heat from reaching the bottom of the joists.  The only way to prevent this problem is to sprayfoam to the bottom of the joists, completely covering the wood.  That would be cost prohibitive, as well as physically impossible in my circumstances.  There is so little clearance in my crawlspace that I was surprised when the insulation company said they had people who could get in there.

Thanks for your continued input.  I've learned a lot in this thread.


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## Perry525 (Nov 25, 2010)

Think of using a steel poker in the fire, leave it in the fire long enough  and the heat travels along the bar by conduction and the end burns your hand, to avoid this, perhaps you wrap the end in a rag, insulating your hand from the heat and you can hold it a bit longer. before you get burnt.

The steel bar heats at one end, the heat travels along the bar, and as it does heat is radiated and convected to the sides, with the bar gradually dissipating its heat until it reaches the point where all the heat is lost into the air, and the far end remains cold in your hand. (for a time)
The heat input, being balanced by the heat loss over distance.

Your joists work exactly the same.

The heat is input from the air above the floor.

The heat travels by conduction down the body of the joist, loosing its energy by radiation and convection to the sides as it goes adding a small amount of heat to your crawl space.

Filling the spaces between the joists with insulation, helps slow down the loss by convection enabling the heat to travel further by conduction, leaving the end/bottom of the joist hotter, sooner and longer.

Wood used to be considered a good insulator, then modern insulators like, polyurethane, polystyrene, aerogel etc came along, things that slow the loss of heat to a far greater extent.
And wood became a heat conductor and the weak link in keeping your home warm.

There is little heat loss through the floor, compared with your windows, ceilings and walls.

However, because our feet are in direct contact with the floor, our body heat quickly disappears downwards into the floor and out into the cold sky and we can end up with cold feet.

Something, we do not feel so intimately, with our body's insulated rather more by warm air when indoors, but stand with your back against an uninsulated cold wall and you soon notice the heat loss.

Its interesting, that many people loose a 2 or 3 foot wide strip along their outside walls during the winter, with the heat loss through the air into the walls making that part of the room unusable.


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## GBR (Nov 25, 2010)

&#8220;Kindly note that foam shrinks over the first 5 to 10 years by 15%.&#8221; ---- Perry, I&#8217;ve researched that statement and only found SPF will shrink only when improperly mixed (two parts). 

You may find this interesting:   BSI-009: New Light In Crawlspaces &mdash; Building Science Information

Why open cell foam/ 
&#8226;	&#8220;In climate zones 5 through 8, the &#8220;air impermeable insulation&#8221; must be a vapor retarder (Class II; 1.0 perm dry cup or less), or have a vapor retarder coating or covering in direct contact with the underside of the insulation. For instance, an air impermeable but vapor permeable spray foam (0.5 pounds/cubic foot) would not meet this requirement, unless a vapor retarder coating were applied (R806.4.4).&#8221;  IRC FAQ: Conditioned Attics &mdash; Building Science Information
&#8220;On the other hand, open-cell spray foam (average density, 1/2 pound per cubic foot) is not a vapor retarder. Installed at a thickness of 3 inches, open-cell spray foam has a permeance of about 16 perms, making it fairly permeable to water vapor.&#8221;     A Close Look at Common Energy Claims - EcoHome Magazine A Close Look at Common Energy Claims - EcoHome Magazine
Air seal the knee walls from the sloped ceiling to prevent air movement behind the drywall. Use the ADA: Info-401: Air Barriers
Air seal the attic and install foam board or house wrap on the attic side of knee wall, under and over it: How to Seal Attic Air Leaks | The Family Handyman
http://www.simplesavings.coop/simplesavings/SIMPLESAVINGS knee walls.pdf
Gary


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## Perry525 (Nov 26, 2010)

GBR said:


> Kindly note that foam shrinks over the first 5 to 10 years by 15%. ---- Perry, Ive researched that statement and only found SPF will shrink only when improperly mixed (two parts).
> 
> You may find this interesting:   BSI-009: New Light In Crawlspaces &mdash; Building Science Information
> 
> ...


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## GBR (Nov 26, 2010)

I've only entered "SPF shrinkage" on the internet search, *where*- outside the U.S.?
Do you remember any more about the article statement? Who, where, why...... ?

Thanks, Gary


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## Perry525 (Nov 27, 2010)

GBR said:


> I've only entered "SPF shrinkage" on the Internet search, *where*- outside the U.S.?
> Do you remember any more about the article statement? Who, where, why...... ?
> 
> Thanks, Gary



Hi, I was researching the European Common Market, following up on their building research pertaining to Passive House building. 

I drop in on this from time to time to see progress.

 They have been studying building insulation since the early 1980's. After Denmark managed to produce some very tight houses that were well insulated but subject to shocking levels of condensation and mold.

 This was then taken up and followed through in Germany and is now going to be standard all over the EU from 2016.

They are working on the basis, that every possible type and style of home can be built to Passive House standard, which in the EU is about a hundred times more demanding than our standards.

I cannot find the article but, here is a USA document that more or less repeats the information, all be it that its writing about polyurethane.

Polyurethane Insulation Materials

Polyurethane is a closed-cell foam insulation material that contains a low-conductivity gas (usually hydrochlorofluorocarbons or HCFC) in its cells. The high thermal resistance of the gas gives polyurethane insulation materials an R-value typically around R-7 to R-8 per inch.
Over time, the R-value of polyurethane insulation can drop as some of the low-conductivity gas escapes and air replaces it. This phenomenon is known as thermal drift. Experimental data indicates that most thermal drift occurs within the first two years after the insulation material is manufactured. The R-value then slowly decreases. For example, if the insulation has an initial R-value of R-9 per inch, it will probably eventually drop to R-7 per inch. The R-value then remains unchanged unless the foam is damaged.
Polyurethane insulation is available as a liquid sprayed foam and rigid foam board. It can also be made into laminated insulation panels with a variety of facings.

Contacts | Web Site Policies | U.S. Department of Energy | USA.gov

They do of course produce sheets of the stuff covered on both surfaces with aluminium foil, this slows the drift as the leakage is only via the edges.

Sorry I cannot provide any more information, when I can, I will come back on this.
Perry.


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## Perry525 (Nov 28, 2010)

Gary, read this article, it frightens me!


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## swindmill (Dec 6, 2010)

Perry525 said:


> Filling the spaces between the joists with insulation, helps slow down the loss by convection enabling the heat to travel further by conduction, leaving the end/bottom of the joist hotter, sooner and longer.



This makes sense.  I still have the problem of being able to access the underside of the floor.  I think I can probably access about 50% of the underside of the floor to insulate it, but I can't get to all of it due to the clearance in my crawl space. When I finish gutting the upstairs over the next week or two, I will have a lot of leftover fiberglass insulation that I could stuff between joists that I can access, if this will be of any benefit. Using spray foam or rigid foam between the joists would be difficult to justify financially.


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## Perry525 (Dec 14, 2010)

Do the part of the floor that you can reach.
Fiberglass is a good insulator, except that most people use it in the wrong way.
To work, fiberglass must not be compressed and it must be fitted inside decent sealed plastic bags.
The bags stop the air and moisture from moving into it and making it useless.
You are still left with the problem, that where an insulation does not fit in a way that stops the air from moving round it, its a waste of time.
But, filling those holes in the walls and reducing the air movement inside the crawl space will help, by reducing convection.
At some point in the future do as proposed earlier, insulate above the floor.


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## nealtw (Dec 15, 2010)

In a modern house with a hand framed roof the rafters would be 2x10 allowing for insulation and strapped with 2x4 to allow for venting above the insulation. What you have is probably {it is what it is } absolutly vent your bathroom and with the age of the house it will find air to pull without adding fresh air for the flat area in the ceiling, What condition is the roof in. If that needs work in the future you could go in from above.
With the idea that any is better than none I would open that area and add at least 4"
and make sure it is vented up there' You may need the ridge vent that you cover with roofing.


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## brendarae (Mar 28, 2011)

hi there, google carson dunlop consulting engineers site and in search punch in ice dams then scroll down the page and there is pictures regarding correctly insulating knee wall atics. this sight has alot of good information. good lick with your project!
brenda


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## gortrixie (Jun 26, 2011)

Hi, I am not a renovator, but I have plan to have several areas of my home updated.  My major problem is that I'm in a 1 1/2 storey log home and that means my main bath is on the top storey and it's like a long skinny triangle.  I need some help knowing how to deal with my awkward space.  Any suggestions?


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## swindmill (Sep 20, 2011)

Believe it or not, I'm just now getting around to actually insulating this half story.  I decided to add a dormer and completely gut it, as I mentioned earlier in the thread. I put a metal roof over the dormer, hoping that it will deflect some of the radiant heat.  The spray foam company is coming by today, and the job should be done next week.  I plan on spraying directly to the underside of the roof. The last time I spoke with the spray foam company, I was told to use open cell so that I'd know if there was a leak in the roof.  The problem with that is that I only have 5 inches along the sloped ceiling. Can I use closed cell if I wish? 

I'm also having the perimeter of the foundation sprayed with 1" of closed cell.


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## Perry525 (Sep 20, 2011)

If you are thinking of insulating the perimeter of the foundation, think about what you will gain  from it. 
Keep in mind that the heat is inside your home and you are trying to stop its escape, or it is outside you are trying to stop it coming in.
Stopping the heat escaping, is best done by having a completely floating floor. A plywood or oriented strand board t&g glued floor floating on three or more inches thick polystyrene sheet.
This will avoid all heat bridges as it will just lay there without needing fixing.
If you are trying to stop the heat coming in then providing some shade to keep the sun off the wall is the first thing to do, inch thick insulation will do nothing.
There is very little difference in the insulation values of open or closed cell foam, more important is the person who mixes the foam and who ascertains that the surface temperature is correct and the days  humidity is right.
Wrongly mixed foam will have a horrible fish like smell for months, if not years, it may not stick and may not have the result they promise. Check they carry insurance, in case they go bust during the guarantee period.


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## swindmill (Sep 21, 2011)

The guy from the spray foam company did explain to me why the difference in R value b/t open and closed is not a significant factor, so I am going with 5" of open cell under the entirety of my roof.  Keep in mind that my main concern is radiant heat, not energy efficiency.  As for the crawlspace, I'm doing it more to condition the cellar/crawlspace than I am for energy savings.  My HVAC runs through my cellar, so I'd like to keep it warmer down there in the winter.  It's also important to me to keep out moisture, and hopefully spider crickets.  My crawlspace has a dirt floor, so they'll be laying out plastic too.  The house is 100 years old, so you can probably imagine how gross the cellar might be.

The company I'm using has been around for over 5 years, and is used exclusively by a well known builder, so I'm comfortable with them.


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## swindmill (Sep 22, 2011)

The spray foam was put in today.  I'm pretty happy with it.  I did find a couple small spots near the ridge where there appears to be a void to the roof.  They're too small to really tell how far they go, but it's certainly thinner in those spots.


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