Putting steel roof on should shigles be removed?

JDJACK

Member
The barn roof is need of repair. This is a older style barn build in 1950's. the boards are tight together on roof, they look good from the inside. (Not pole barn)
One side has 2 layers of shingle and the other side has one.
The 2 layer side is curling real bad.
The plan is to install a steel roof.
The question is should the old shingles be removed before the steel is put down?

What are the effects in the future if any, if the shingles not removed?
 
I think they should. If not I would screw 2x4's to the old roof every 24 in. But my neighbor never just nailed the tin on.
 
By removing the old shingles you will have smoother surface the fasten metal to. Be a nicer looking job.
 
If weight is a factor you should remove them but if that is Ok you can strip it with 1X4s and screw to them. Our house had one layer on it and the installers laid some type of material over the shingles stapled it down then stripped it with 1X4s and screw tin onto them.
If its a steep roof they will use 2X4s as it gives the men better footing.
 
This is the WRONG place to ask!
Go to your local code inforcement office.
The interpintation of how to install a steel roof over existing roof varies widely from town jurisdiction to the next. Your code enforcement officer may have common sense, or he may be an AH who reads the uniform code a bit different. BTDT as a contractor.
Loren, the Acg.
 
Hi, just recently, couple of weeks ago, placed metal on a roof. We left the asphalt shingles on the roof, strapped the roof, used screws, then placd the metal on the roof. Look's just about perfect. I sort of stand back and admire the job, this was on the roof of a building owned by a service club. Completed by volunteer labor. There are many differences of opinion of what you should or should not do. I am happy with the project and as the person who co-ordinated the project. Cheers, Murray
 
Had mine done last year. Shingles were removed and 1x4 were stripped down the roof, then steel fastened to the strips. Don't know if one way is better or not, but I wanted the weight of the old shingles off. They weigh quite a bit when you stop to think about it.
 
saw a local retired contractor(a good one that ive known all my life) put strapping over the shingles and screw steel to the strapping this summer. If he thinks its alright to do to his own house, then I wouldn't second guess him.
 
2" X 4" nailers running horizontally over the shingles, spaced 24" apart works fine for steel roofing. The issue is weight. You need to determine if the roof is designed to handle the weight of 2-3 roof layers plus the needed snow-load rating.
 
Having mine done right now they are laying some kind of paper over the singles... There is nothing wrong with my singles other than they are 18 years old I have the money and hope its the last roof I will ever have to replace on this house... Check out the cutter this guy made ... He lift the wood frame and clamps in place with a rope and a board he steps on... Then pulls a rope to pull the saw thru the cut... its neat

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They lay a metal strip around the edge of the roof and crip the metal so it fits under the strip...
 
Going over old shingles shouldn't be a problem "if" they are laying flat. But I would be afraid the curled shingles would tend to flatten out from heat and weight of the steel, leaving the screws loose.

A potential leak around the screws, (that may not be a big problem in a barn), but over time the screws will rust, and the wood rot, causing the screws to loose their grip.

Either remove the shingles or put down nailer strips to get a positive surface to fasten to.
 
If it is a barn roof on a farm building here in New York state it is exempt from local building codes so no building code inspection is involved.
 
Neighbor put down strips over asphalt shingles; bragged that he didn't have to remove the shingles.

It took him over 2 years to fix all the leaks.

Remove the shingles; it's not that hard of a job.
 
Do the math. Shingles weigh about 240 pounds per square. If your roof is 3000 square feet, with two layers on one side and one layer on the other, that's over five tons of roofing material that isn't doing anything for you. The steel roofing is lighter than shingles, but it will still be about 100 pounds per square or another 3000 pounds. How much weight do you figure your trusses are good for? Not to mention the barn walls, which also need to support the weight of whatever is in the loft.

Tearing off shingles is a lot of work, and it's human nature to take the easy road. Do it right and your barn will be around for another 60 years. Go the cheap and easy route and it just might collapse under its own weight the next heavy snowfall.
 
I saw a contractor put something like fan fold, 1/4 foam insulation, over shingles before putting metal on a house. I'm waiting for that to cause an issue. All the flexing we have with snow load.

I was plowing snow from driveways when I hear a racket. Looked over at house with metal roof and there was an avalanche of snow sliding off the roof. The guy had to remove a large pile of snow before he could get his cars out of the garage.

I thought that could be dangerous if his grand kid was standing there.
 
Take the old shingles off. That way you won't be wishing you had in a few years. Don't believe a contractor when he says he knows how to do it. I've seen a lot of metal roofs put on wrong. Got one on my house that was put on before I bought the place. Some nails just hang in the air . Read the manuals and watch them close.
Manufacturers Manuals
 
Everyone has their opinion on this, I would put down 30# felt then add the steel, if the side you say is curling bad, I may opt for two layers of felt, then the steel. As long as your existing roof has not failed and you do not have any rot, I see no reason to remove shingles and have the huge mess to clean up, but again, everyone has their opinion.
 
(quoted from post at 18:03:22 10/27/14) Everyone has their opinion on this, I would put down 30# felt then add the steel, if the side you say is curling bad, I may opt for two layers of felt, then the steel. As long as your existing roof has not failed and you do not have any rot, I see no reason to remove shingles and have the huge mess to clean up, but again, everyone has their opinion.

My roofer said it depends on what you have to screw to and if you have dips/sags in the roof... I would have my doubts about the way I went if the steel was screwed in the flats on any surface... I have built four metal buildings and they will leak around the screws in time, the screw seal is the weak link.... That's why I went with a standing seam up-grade...

I have a wood frame OSB sided building I had covered with steel. On the side that gets direct sun all day the screws will back out...
It should have been stripped... The building had tin on it so it was already stripped and a new steel roof installed I have not had any issues in 14 years with leaks... I also had it insulated with vinyl backed insulation so if it leaks I don't know it YET....
 

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