# Replacing metal roof with asphalt shingles



## Chris (Jul 27, 2017)

So my metal roof sits on 1x8's strung across the trusses that have gaps between them. I am going to pull the metal and sheet the roof. Do I need to pull off the 1x8 or just sheet on top of them? Also many houses out here have roof vents that are metal boxes towards the ridge, I have never seen these before moving here, is there any calculation to know how many or where to place tgem if they are even needed? About 1/4 of the houses I see have them.


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## Sparky617 (Jul 27, 2017)

What is wrong with your metal roof to make you want to replace it?


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## Chris (Jul 27, 2017)

Sparky617 said:


> What is wrong with your metal roof to make you want to replace it?



It's probably close to 80 years old and insurance will cancel me if I don't change it. I am sure it leaks in places, its not in the best shape.


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## Chris (Jul 27, 2017)

This is the roof 

View attachment 1501174132017.jpg


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## oldognewtrick (Jul 27, 2017)

On what center is the rafters?

Install shingle over ridge vent, works a lot better than the boxes. The box's end up with stagnet air in between them, with ridge vent you have constant exhaust from the run of the ridge.


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## nealtw (Jul 27, 2017)

Just sheet over the strapping


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## oldognewtrick (Jul 27, 2017)

nealtw said:


> Just sheet over the strapping



And nail into the rafters, not just the strapping. AND, you better get the hose out and water that grass...:beer:


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## nealtw (Jul 27, 2017)

oldognewtrick said:


> And nail into the rafters, not just the strapping. AND, you better get the hose out and water that grass...:beer:



The have all the lawn chairs out to watch the parade.


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## Chris (Jul 28, 2017)

oldognewtrick said:


> On what center is the rafters?
> 
> Install shingle over ridge vent, works a lot better than the boxes. The box's end up with stagnet air in between them, with ridge vent you have constant exhaust from the run of the ridge.



How is ridge vent done? I believe they are on 24" I will double check. This house has an addition and if I remember correctly it no longer has trusses but just rafters. I'll get some pictures next time I'm over there.


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## Chris (Jul 28, 2017)

nealtw said:


> The have all the lawn chairs out to watch the parade.



Modern technology. I can't speak any I'll will. The lady died in the house and I don't need her mad at me.


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## JoeD (Jul 28, 2017)

Put a new metal roof on. You never have to do it again. Asphalt you will be doing again in 15 years.


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## Chris (Jul 28, 2017)

I thought about that. I will have to weigh out the cost difference


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## oldognewtrick (Jul 28, 2017)

You should be able to put a screw down metal roof on for about the cost of installing a dimensional shingle.


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## Sparky617 (Jul 28, 2017)

Looks like a fairly simple roof, and single story as well.  You looking to DIY or hire it out.


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## bud16415 (Jul 28, 2017)

Give the Amish a call. They will knock that out in 3 hours for 200 bucks labor.

Opps Amish don't have phones.


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## oldognewtrick (Jul 28, 2017)

bud16415 said:


> Give the Amish a call. They will knock that out in 3 hours for 200 bucks labor.
> 
> Opps Amish don't have phones.



Chris said there's no Amish in Idaho.


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## Chris (Jul 29, 2017)

Still haven't found any amish.

Plan on doing it myself with a helper. What do I do about drip edge


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## nealtw (Jul 29, 2017)

Chris said:


> Still haven't found any amish.
> 
> Plan on doing it myself with a helper. What do I do about drip edge



You can cheat the drip edge. A bead of caulk just back from the edge on the under side will do the same thing.


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## bud16415 (Jul 29, 2017)

The way the guys did mine there are shapes rolled for every possible transition. The drip edge was a piece about 9x6 like a flashing that went under the roofing and down over the face. It had a flare off the bottom edge. Then the roof extends an inch past. There is a different shape for the edges that overlaps on top of the roofing but past the first ridge in the roofing. He also had some really sticky thick double sided tape he used and foam pieces shaped like the roofing.


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## oldognewtrick (Jul 29, 2017)

If it were mine, I would use drip edge, capping, transition flashing and cover the rake edge with preformed metal. Don't use roofing felt as an underlayment, use a high temp peal and stick smooth back underlayment. Where you order the panels will also have all the accessories you will need. 

Roofing felt will degrade over time from exposure to the high temp of contact with the metal.


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## bud16415 (Jul 29, 2017)

oldognewtrick said:


> If it were mine, I would use drip edge, capping, transition flashing and cover the rake edge with preformed metal. Don't use roofing felt as an underlayment, use a high temp peal and stick smooth back underlayment. Where you order the panels will also have all the accessories you will need.
> 
> Roofing felt will degrade over time from exposure to the high temp of contact with the metal.



If he has 1x8 purlins running across his roof and he takes the old tin off to replace it wouldnt he just put the new tin back directly to the purlins. Should there be strips of the peal and stick covering the purlins?  Or are you suggesting he cover the purlins with sheathing like he was going to shingle and then the peal and stick and then the tin?


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## oldognewtrick (Jul 29, 2017)

All metal roof mfgs suggest installing over solid decking. Condensation will occur under the panels in the right condition. There should be a barrier to eliminate this from happening.


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## oldognewtrick (Jul 29, 2017)

If he shingles the roof, he will need to install solid decking anyway. Forget the cheap shortcuts, pennies now are dollars later.


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## nealtw (Jul 29, 2017)

Just fill in the gaps in strapping where the ice shield goes. Likely a good time to add a few inches to the height of the front roof as there little or no insulation there.


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## JoeD (Jul 29, 2017)

Never heard of the requirement for sheeting under a metal roof.


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## oldognewtrick (Jul 29, 2017)

JoeD said:


> Never heard of the requirement for sheeting under a metal roof.



Like a lot if things in life, most folks don't read the fine print.


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## bud16415 (Jul 29, 2017)

I know the roof I just had done by the boys with straw hats using ag roofing was the short cut method they have been doing around here for the last 30 or 40 years. Maybe 1/3 of the houses up and down the road are now done this way. As an example my 1800 SQ FT 2 story house with 8 facets to it one hip section cost me 2000 for material all 26 gage tin and all 2X stock for the build outs purlins and frame. And 1000 for labor to put it on. I would loved standing seam residential material done to the process oldog is describing but I think I would of ended up about 3 times the cost. Time will tell how this works out but I have talked to dozen of people that did this method and they are happy long past where shingles would needed replaced. My roofs are 10/12 pitch and with the 1.5 air gap in there now I will say the attic hasn&#8217;t been this cool during the 90 deg days we have been having and the roof is a dark green in the 4 years we have been here and my guess is in the 130 years the house has been standing. We got our old eve venting going on and we now have this air movement under the new roof and ridge venting. Part of it could be when I took the chimney down I left the hole at the ridge and the attic can now vent into the ridge there. We have had some hard rains and nothing seems to be getting in there so I will leave it open for now. 

My biggest hope is the roof will now shed snow during the winter better. I didn&#8217;t have them add any of the snow catchers to the roof. About half the roofs here have them and half don&#8217;t. most of the roof doesn&#8217;t have gutters also.    

I&#8217;m assuming the roof Chris is talking about is on a rental house he is rehabbing. Almost all the landlords around here are covering old places up with the short cut ag method. The only people I hear not happy with them are the firemen as they cant get water thru the roof when needed. On the other hand the fire hall has this roof as do most of the firemen I know. Like I said I was leery of doing it but was willing to see how it worked for the price. Changing shingles all the time it seemed anyway was getting old for me. if this lasts 40 years like they say I&#8217;ll be 102 and wont give a damn. Haha.


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## buffalo (Jul 30, 2017)

Under my metal roof is a plastic liner , and under that bubble wrap insulation . All installed on Perlins over trusses , no sheeting.


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## mabloodhound (Aug 17, 2017)

Stick with the metal roof.  Last a lot longer than shingles.  Plus it's enjoyable to listen to when it rains.


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## Chris (Aug 17, 2017)

I ended up sheeting and going with shingles. I like the metal but on this house I think the shingles will look better. House is about halfway done now.


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