# Enclose area under house



## jmg1213 (Aug 15, 2014)

We have recently purchased a small cabin that sits on a rather steep hill. I have included a photo, but the only one I have available at the moment so not the best angle.  The house sits on wood posts that go into the ground and I assume sit on concrete footers.  I want to enclose the bottom of the house, primarily to help insulate under the house, provide additional stability, to provide some storage area, and maybe even install central hvac, but it would not be a living space.  I am trying to determine the best way to do this, but the steep grade is a big concern.  I am thinking of building walls between the posts and looking for ideas on doing this.  I am thinking that the posts would remain as the points holding up the house, so I do not know how that would affect putting in foundations for the walls.  Any suggestion?


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## bud16415 (Aug 15, 2014)

What a view. I&#8217;m not an expert but if you feel the posts are doing their job and I don&#8217;t see any reason to think they are not. (Did you have any kind of inspection done prior to buying?) if everything is good structurally I would just add some non-structural framing (pressure treated)and cover it with some sort of skirting material Maybe T 1-11 or similar or even fiberglass panels for an unheated space. blocking the wind alone I think will keep the floors a lot warmer. 

Will you use it year round? What will be the lowest temps you will be seeing?


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## jmg1213 (Aug 15, 2014)

There is a slight sway to the house, and we did not have an inspection done.  The posts are in good condition, but I figured it would not hurt to add the additional stability as well as keeping the cold breeze out during the winter and gaining some storage space.  This is currently a second home in the eastern part of WV, so it can get somewhat cold with avg highs in the 40s and lows in the 20s.  We plan to eventually live here full-time.


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## nealtw (Aug 15, 2014)

Closing it like Bud said would not be a problem, but leveling the floor might. You wouldn't want to undemine the the posts at the front of the house. If it is just for storage maybe a raised floor.

You don't want to do a concrete foundation as that would require retaining walls above and below the house.


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## bud16415 (Aug 15, 2014)

If it has a little sway this is the time to fix that also with some diagonal bracing of some sort in both directions. I would put these on the inside of the poles and your strapping for the skin on the outside maybe just like they build pole barns. You could even cover it in pole barn siding it comes in lots of colors now and would work good for this. 

Neal is right I wouldn&#8217;t mine all that slope out if you want a floor in there leave the grade alone and build the floor with steps to it for storage.


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## jmg1213 (Aug 15, 2014)

As part of this project, I was thinking of having a couple of levels for the floor, but I also was thinking of doing some leveling in combination with building the floors.  Bud16415, instead of cross bracing, I was thinking that the use of sheathing that attaches to the posts would help, much like retrofits done in earthquake prone areas.


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## slownsteady (Aug 15, 2014)

> ...The house sits on wood posts that go into the ground and I assume sit on concrete footers....



You know what happens when we assume....?

My concern would be if the new walls put any additional stress/strain/load on the posts. Especially if that hill catches a strong winter wind. And disturbing the ground on such a slope as you have, might have it's problems also. If you are going to do anything but the absolute minimum, you might want to consult an expert. In the meantime, make sure that the floor is well insulated.


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## jmg1213 (Aug 15, 2014)

I appreciate those that have chimed in.  I was looking for some initial input on my ideas, and as Slownsleady suggests, I will need to have a professional look at the situation and give me some definitive answers as to what I can and cannot do.


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## Jungle (Aug 15, 2014)

All your footings are rotten because it is wood set in concrete like a fence. Foundations like this only last 10-20 years. Your house sounds dangerous if " There is a slight sway to the house,"
I would suggest you contact a professional, my guess is you need major foundation work.  That's when people generally sell houses btw...


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## nealtw (Aug 15, 2014)

This may be driven pilings with no concrete, any rot either way will be at or close to surface and is fixable.
The real questiopn is how deep the front posts are and how much is required to be below grade. You would have to locate the original engineers report from the permit dept.
That is why I said you wouldn't want to stay away from to much leveling.


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## bud16415 (Aug 16, 2014)

You are correct panels will also provide diagonal bracing. The problem is most sheets come 4x8 so you have the seams that are weak points in the system. Long pieces of wood or even cables going corner to corner will stay in tension. I don't think your posts are rotten and if they were you would see it most at ground level or slightly below IMO


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## jmg1213 (Aug 16, 2014)

There is no evidence of any rotting of the posts, they are in good shape. Here is a better angle of the house (though a little far away).


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## Wuzzat? (Aug 16, 2014)

In the enclosed space you should probably have a vapor barrier covering the earth and thermal insulation if the 30F to 50F ground temperature is objectionable.


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## daltonbrain (Aug 17, 2014)

Remove the existing insulation and have the underside of the floor sprayed with polyurethane insulation. It provides excellent r-values and blocks out all air intrusion. I wouldn't recommend a water-blown product as these are more prone to moisture retention. 

Mike


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## nealtw (Aug 17, 2014)

Get up close and get some photos of the posts and beams and floor joist and get some measurements of beam size and length. What is the head height at the center of the house.


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## jmg1213 (Aug 18, 2014)

Good suggestions, guys.  I will be going by the house this week, so I will get some pictures and measurements and post.


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## jmg1213 (Aug 20, 2014)

There are 12 posts (6x6) that support the house (24' x 30'), plus the posts (also 6x6) that support the deck on two sides of the house. There is only one beam that runs down the center, the length of the house that rests on the four center posts.  This beam is constructed of two 2 x 10s that sits in a notch in the posts.  The underside of the house is covered with an insulating fiberboard with insulation blown in between them and the subfloor.  This limits my ability to fully see the floor construction.  The four outside posts on either side of the house attach to the floor joists which are 2 x 6s.  Here are a few pics. The ones with the 2x4 and level are to help give more perspective on the slope.


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## oldognewtrick (Aug 20, 2014)

Does the area under the cabin remain dry when it rains?


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## nealtw (Aug 20, 2014)

The little shed under the house is a furnace closet, yes,no?
What kind of floor doesw it have concrete, wood?
Will you be happy with six feet to the floor almost seven feet other than under beam?
Have you poked around thew posts to see if there is concrete around them?

Everything else is fairly simple.


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## jmg1213 (Aug 20, 2014)

The closet houses the water line which is insulated and has a dirt floor.  I realized that I may have less than 8' of height in the finished area, so that is okay since it will be primarily a storage area. The area under the house remains dry when it rains.


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## nealtw (Aug 20, 2014)

Plan A is for a floor, Plan B is for closing the bottom.

Plan A Use double hdg hanges to hang double 2x10 untreated between the bottom 3 posts
                                                                     treated between the middle posts.
We always build with 2x10 floor joists 16" on center with hangers between those beams. Cheating the size is up to you.
In order to do that you will have to dig alittle around the middle posts and reshape the fill a little as we don't want any fill sluffing down and pushing against this floor, best would be to have about 6" cleareance under the beam. The water shed I think will be hung from the house so I would be going for an elevation the would put your plywood floor under the door into that shed.
5/8 t&g plywood.

I would rmove the dirt under the shed too and later refill that with gravel so it won't retain water and push against the floor.


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## slownsteady (Aug 20, 2014)

The suspense is killing me! Where's Plan B???     :beer:


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## nealtw (Aug 20, 2014)

Less confussion if we deal with one set of qestions first, you will have to stay tuned.


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## oldognewtrick (Aug 21, 2014)

nealtw said:


> Less confussion if we deal with one set of qestions first, you will have to stay tuned.



Sounds like _somebody_ has misplaced "B"


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## nealtw (Aug 21, 2014)

oldognewtrick said:


> Sounds like _somebody_ has misplaced "B"



If I have misplaced it, it will be in the last place I look for it.:


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## jmg1213 (Aug 21, 2014)

I think the 2x10s are a good suggestion to provide maximum strength and stability.  As far as the closet, I am aniticipating making some modifications to it.  I want keep that area enclosed and well insulated, but I can reconfigure the access into it as necessary to accomodate the floor.


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## bud16415 (Aug 21, 2014)

I helped my nephew do something similar only not as much grade at his place and we took advantage of the area below the deck also. I think if it was mine and as long as I was closing it in I would include the deck area also in the plans.

On his we hung corrugated panels below the deck on an angle sloping away and into a gutter just inside the outer wall to carry the rain running thru the deck away. It worked pretty good for the type of storage area he wanted. Mowers, motorcycles and 4 wheelers etc.

You could actually have a double wall if you wanted the area under the house the dry space and the area under the deck the protected area. In my experience when you have a layer or two layers of unheated areas around a warm area each layer acts as a thermal zone keeping the heat in. 

I like Neals plan A for framing also depends on how fancy you want to get with a floor in there. I could also see some 4x4 posts independent of the main framing kind of a floating deck under a house just to walk around on and store things. 

One question did they ever have any trouble with the exposed drain lines in the winter? 

Waiting on plan B also.  
Neals plan B is kind of like the old saying There are 10 types of people in the world. Those that understand binary and those that dont.


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## Wuzzat? (Aug 21, 2014)

oldognewtrick said:


> Does the area under the cabin remain dry when it rains?


If yes, good grading and 
a low groundwater level and/or no aquifer near the house and
porous soil and 
. . .?.

If no, one or more of the opposites.

Right?

I don't do programming anymore but I can always use the practice in writing and debugging logical statements.


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## slownsteady (Aug 21, 2014)

If you are going to modify the closet, turning the door to the inside, if possible, would add to the insulated value of the closet.

Don't forget to plan on access for wheeled tools/vehicles. Even something like a wheelbarrow benefits from not having to thump down steps.

Bud brings up a good point: are you planning a closed floor or something open like a "sub-deck"? I don't remember seeing any dimensions for floor space under the house vs. floor space under the deck: will they be separated?


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## slownsteady (Aug 21, 2014)

A more basic question: I don't see an access path that leads down to the area. I think lugging stuff up & down that hill will become a drag awfully quick. so before you invest time, effort & money, consider how much you will use it.


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## nealtw (Aug 21, 2014)

Slow: the closet door is already facing what will be the floor of the new deck

Bud, we build houses on hills like this all the time, !00 tons of concrete usuall is enough to hold back the hill that is sliding towards the house. In this case they minimized the flow resistance by using posts, so I would stay away from adding to much more to change that.

You guys want to talk about the deck, test time. Find four thing wrong with with the construction, that you can see.


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## oldognewtrick (Aug 21, 2014)

1. space between the railings where a child could crawl through.


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## nealtw (Aug 21, 2014)

So now there are five.


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## nealtw (Aug 21, 2014)

jmg1213 said:


> I think the 2x10s are a good suggestion to provide maximum strength and stability.  As far as the closet, I am aniticipating making some modifications to it.  I want keep that area enclosed and well insulated, but I can reconfigure the access into it as necessary to accomodate the floor.



If you have no questions or discussion about the floor we can go on with the rest. 
First thing is to check closely the posts, pressure treated posts rated for underground or ground contact has been incissed, hundreds of little cuts in the surface to allow more treatment to enter the wood. Can you confirm the cuts are there.


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## jmg1213 (Aug 21, 2014)

I have not planned on placing any type of floor/deck under the deck, only the house.  The spacing between the posts is approx. 12ft one direction and a little over 9ft the other.  Originally, I was thinking more of a closed floor, but a wood floor/decking may be easier and cheaper.  The reason for a closed floor is that I may want to add central hvac and locate the unit here making it necessary to enclosed the whole area.  Currenty, heat is from a propane heating unit located in the living roomWe have not been here for winter, but I was told that there have been no problems with freezing, but this is another reason I would rather enclose it.  I do plan on installing wood stairs down both sides of the house once the underneath is done. The side with the closet is less steep and as you go away from the house from that side, the ground levels off.  I will be getting an ATV that I will want to store in there.  I will not need a mower at this house since there is no lawn.

I am also waiting to hear about Plan B.


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## jmg1213 (Aug 21, 2014)

Neal: I will check on the incising tomorrow.


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## nealtw (Aug 21, 2014)

Is the deck the same level as the floor of the house or do you step up into the house?


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## slownsteady (Aug 21, 2014)

> You guys want to talk about the deck, test time. Find four thing wrong with with the construction, that you can see.



no joist hangers?
maybe needs a beefier rim?

Are you going to answer this before or after Plan B?


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## nealtw (Aug 22, 2014)

I am concerned about water entering the floor structure of the house because of the way they built the decks but we can deal with later.

Plan B  After re-shaping the fill under the house to allow for the floor in Plan A . Place a 6x6 ground contact treated post on the ground cut to fit between the post. Attach them to the post with HDG strap ties.
To that attach a treated 2x4 which will be the bottom plate of the wall.
With reg. lumber, top plate nailed to the floor joists above and cut studs to fit, there are tricks to make measering these pretty easy.
Any nails or screws going into treated wood must be HDG.
I would do this to the front of the house to as it looks like you have fill or rocks filling the space now. It might be tricky, up for discussion.
Cover the walls with 1/2 plywood.
Hills move all the time, you may not see it but that is why concrete driveways on mountains are allways cracked after few years so my thinking is everything is attched to the posts will allow the earth to move a little or a lot with out damage to the house.
Someone suggested vapour barrier on the ground under the house, it might be best to stretch it out and lay the timbers on top of it. That will keep it in place.
Wood treated or not will rot over time and that happens mostly where water and air meet at the surface of the ground so keeping everything dry is helpfull. With that in mind I would dig a shallow trench across the front and down both sides and install perferated drain pipe and cover that with drain rock.

Back to the deck. Codes have changes on how to attach a deck to the house. The construction of the deck looks like something from the 1900s which is fine but the attachment want to be looked at.
There should be there should be tar paper or house wrap between the floor rim joist and the deck joist. And then because vinyl siding does not do well holding out rain water it is important that the water is stopped with the house wrap and at the bottom it needs a way to drain out. What there should be under the deck board and over that first joist is HDG flashing or a plastic flashing.
Without that, water can enter that joist and work it's way into to floor rim joists and cause rot.
Any problem with the rim joist will want to be dealt with before you build walls and make it impossible to work on.


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## nealtw (Aug 22, 2014)

slownsteady said:


> no joist hangers?
> maybe needs a beefier rim?
> 
> Are you going to answer this before or after Plan B?



Hangers, flashing under the deck boards. insicing on the posts and I don't remember the 4th but it will be right where I left it.:banana:


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## nealtw (Aug 22, 2014)

Yes the rim should be double.


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## jmg1213 (Aug 22, 2014)

The deck is the same level as the house floor; there is no step down.


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## jmg1213 (Aug 22, 2014)

The house is located in a sparsely populated county, about 8000 people when the house was built in 1993 and only about 7500 now.  As such, I am sure the building codes are loosely enforced, so it probably explains the deficiencies in the construction.  I want to take this opportunity to make improvements along with the intitial project discussed here.


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## slownsteady (Aug 22, 2014)

I don't think anyone is suggesting you rebuild the deck. It's more of an exercise in observation.


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## bud16415 (Aug 22, 2014)

The only statement you made so far and also all the advice given so far that I have any concern about is the issue of a sway you can feel. I recently built a low deck about 3&#8217; height and I really gave it the shake test about half way thru and could detect a very little sway and I went for the cross bracing. In your case with the height and the weight not to mention the expense and safety I would be really studying what I wanted to do about that before anything else. Even some iron work with turnbuckles might be in order. I was also thinking and Neal and others might have a better input on this but to allow max head room below maybe a ledger made from ironwork on both sides with clips welded in for the joists and maybe even ends to except the cross ties for the sway.


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## nealtw (Aug 22, 2014)

bud16415 said:


> The only statement you made so far and also all the advice given so far that I have any concern about is the issue of a sway you can feel. I recently built a low deck about 3 height and I really gave it the shake test about half way thru and could detect a very little sway and I went for the cross bracing. In your case with the height and the weight not to mention the expense and safety I would be really studying what I wanted to do about that before anything else. Even some iron work with turnbuckles might be in order. I was also thinking and Neal and others might have a better input on this but to allow max head room below maybe a ledger made from ironwork on both sides with clips welded in for the joists and maybe even ends to except the cross ties for the sway.



The walls will do all thatand he may add a wall mid house at the end of the new floor, there will be no movement.


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## jmg1213 (Aug 22, 2014)

I checked and the 6x6 posts do not have the cuts in them.


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## nealtw (Aug 22, 2014)

You will want to talk to some local lumber yards to see if they could be full treated for gound contact. A closer inspection would be in order at gound level and mayber something else could be added to protect them.
http://www.oldhouseauthority.com/archive/wood_rot


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## jmg1213 (Aug 24, 2014)

I will check on getting the posts additional treatment or other options to prevent/reduce any future rotting.  I don't want to rebuild the deck, but any suggestions of improving what is there (if possible) is appreciated.  I have found information on permanent wood foundations.  Neal, though what you are suggestion isn't exactly the same this, I think there are some things I can incorporate.  Would laying a gravel base be a good idea?  How about using a vapor barrier as mentioned earlier, and have it come out and wrap up the sides of the 6x6s running between the post?  Here is a picture from Southern Pine PWF guide, which shows construction for a basement but seems relevant.


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## slownsteady (Aug 24, 2014)

jmg1213 said:


> I checked and the 6x6 posts do not have the cuts in them.



coincidentally, the phone company recently put in a couple of new poles not far from my house. I looked carefully at them and they are not scored (incised). They are actually rather smooth. I wonder if the technology has changed.


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## nealtw (Aug 25, 2014)

When I worked in a treatment plant many years ago, all timber was incised and green poles were if the were fir but most poles were cedar and treated with penta, the brown stuff. Incising a pole was fun, it was like swinging a sludge hammer that stuck where you put it.
But yes treatment might be different for different wood.


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## nealtw (Aug 25, 2014)

The poly wraping the timber on the ground ,I thinjk yes. You wouldn't bring it up onto the sheeting like they did. Your sheeting will want house wrap so vapour can get out.
I think they build all that with treated and you won't need that just the stuff that sits on the ground and could get wet for insurance..

I think we can come up with something to correct the deck. Are the deck boards screw or nailed down? I wiish they had come into the 1900s when they built it.


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## jmg1213 (Aug 25, 2014)

The deck is nailed.


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## nealtw (Aug 25, 2014)

You will first want to have a close look under the deck board from under where they meet the joist against the house and make sure there is no flashing there.
If it's not there you want to open the insulation cover and inspect the rim floor joist for water staining and softness, use a screwdriver or awl if you have something like that. Yes all of it.


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