Replacing metal roof with asphalt shingles

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.

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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?

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.

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

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.

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

JoeD said:

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

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

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’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’t have them add any of the snow catchers to the roof. About half the roofs here have them and half don’t. most of the roof doesn’t have gutters also.

I’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’ll be 102 and wont give a damn. Haha.

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

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

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.