Metal roofing

That seems OK for Louisiana. But it needs to meet Local building codes. If aluminum, use only aluminum rated fasteners. Jim
 
Yes roof.
Its my home.

I have shingles now but some of the OSB is damaged and other is soft.
People keep telling me just put 2x4 furring directly over shingles and leave soft OSB in place.
Just make sure you bolt the furring to the trusses.

Heck for $500 more than furring I can replace all the OSB with new.
Yes lots more work but this is my home.

Question is if I replace all the OSB do I need furring strips ??????
 
John.
What might work in Indiana may not work in your hood. Temperatures and humidity are different.
Best answer, I don't know.
I would ask people who install metal in your hood.
Condensation is my concern.
 
About 25 yrs ago I put steel roofing directly over shingles. Twice a year, in the spring and in the fall, I get to listen to snapping, and popping sounds coming from the roof. It is annoying to me. If I were to try to sell the house, I would most likely need to do so when the roof is quiet.
 
You might need some air space between the steel and the OSB to help keep the OSB from rotting and the steel from rusting on the underside in your hot humid climate.

This post was edited by fixerupper on 09/20/2021 at 12:10 pm.
 
My opinion is it would be okay. Check with roofing manufacturer that underlayment is compatible. If not it voids all warranties.
 
John, I just had galvalume put over my 2 layers of shingles.
The roofer who we have known for years said he had to put down the waterproof paper under the metal to get the warranty on the metal.
His wife's family runs the metal factory.
He does this all the time.
I think the metal over OSB with the paper would be fine.
And he put the screws in the ridge like it should be done.
We are VERY happy with our roof.
I will never nail another shingle on, unless it is a metal shingle.
Richard in very humid NW SC where we get from zero to 100 degrees during some years.
 
2005 Had a tornado go past my house took out sliding glass doors and part of the roof. Wanted to goto metal roofing insurance said it had to be the same material as old. Roofer said fine it will cost another $2000 to do a tear off to replace the plywood under the shingles that was damaged or I can put 1x4 over the damaged areas and put metal on like the customer wants. Insurance went for it. House is cooler no leaks no problems yet.
 
I agree with the cooler part.
Much easier to cool with the galvalume reflecting the heat instead of the old shingles absorbing heat all day.
 
When we built our cabin we put tarpaper on the OSB and screwed the steel directly to it, been OK for 20 years, and quiet, but we have a foot of insulation in the attic. Not sure what you mean by synthetic underlayment, like Tyvek?
 
John, the only experience I have with metal roofs is up here. Never dealt with them in Texas.

That said, the reason that roofing felt or other barrier is used is due to condensation. I would imagine you have exceptionally high humidity -- as in, fish swimming through the air! *lol* If it were me, I would put some sort of barrier between steel and sheathing.
 
John - I believe I would try to leave a vapor barrier between the metal and the OSB. Your OSB would likely rot from condensation before too long if there is no room for them both the breath. Good luck - Bob

cvphoto101777.jpg
 

Mine is over singles a standing seam roof. They laid a barrier of some sort it was in a roll like house rap. Their is no OSB if it were mine I would replace any that's worn/rotten etc...

They put a wide metal strip around the perimeter of the house the roof is rolled over and tucked under the metal strip. He said it would keep it from blowing off.
 
It will dent if hail hits it. New roofing in June 2021. Dented in recent hail storm a few weeks ago.
 
John - pick up the phone and call the manufacturer of the metal. That's what I did, and they gave me a ton of advice on things that I would not have thought of on my own. As to your question, the manufacturer of the metal that I used recommended 1/2 inch closed cell insulation board under the metal, with roofing screws through the flats and going at least 1 inch into solid wood. I'd like to mention that I must have gotten five different opinions from the people at the lumber yard where I bought the metal. That's what prompted me to call the manufacturer.

The metal manufacturer wants your roof to turn out good - maybe as much as you do.
 
I had my house and garage re roofed with metal in 2019. They removed the shingles and replaced one damaged sheet of OSB. They put down an underlayment that was white colored and that was designed for metal roofing; it was not tar paper and was probably synthetic, like you are describing. The sheet metal was screwed directly to the OSB, over the underlayment. Good luck with all your damage problems. Mark.
 
Unless you are lucky enough to hit the rafters with the screws it won't work. They need 1 inch in the wood here. Where you are that might not be enough. The furring strip don't add that much expense and makes it a lot safer for the installer.
 


Standing seam metal roof is great. All the rest will start to leak at the screw holes in 15 yers. The holes get elongated by the expansion and contraction.
 
(quoted from post at 15:02:22 09/20/21)

Standing seam metal roof is great. All the rest will start to leak at the screw holes in 15 yers. The holes get elongated by the expansion and contraction.

That may be your experience, but not ours.

First let me say, I DO NOT like when nails are used for steel roofing rather than screws. However, a new roof was put on this place before we bought it over 20 years ago. They used nails (yes, with the rubber washers). To date, no leaks.

I've yet to know if a leak from any roof I've installed using screws, and I haven't done a roof in about 15 years.

That said, I agree that a standing seam is superior to exposed fasteners.
 
I do not think it is a good solution. Here is why.

We built a new house and had it sheathed solid with 1 x 8 pine. The metal roof would get hot and then cool and that caused expansion and contraction and worked the screws out and stripped/wallowed the wood out till they would not hold and we had leaks.

We removed the metal, put down new underlayment (synthetic) and screwed 2x4 southern yellow pine to the trusses and reinstalled the metal. Never had another screw work loose or strip out. It would have been cheaper to do it correctly the first time, but we followed the metal sales place and lumber yard recommendations. We finally called the metal manufacturer and they said that 1x8 and OSB was a no go. If we wanted it to stay go with a 2x4 and they make sure it was yellow pine.

The wood screws need some material to screw into to stay stationary as there is a lot of force acting on them.

Here is the screws we went with the second time.


mvphoto82116.jpg
 
I worked on an office for a farm business a few miles over 20 years ago. We built a 24x40' pole structure with an 8' ceiling which was fine for a time. He had me put ten test over the 2x4 roof strapping. I didn't like the idea of it as some have said because of condensation, but working on it was nice as the half inch ten test gave the steel some added support if your footing was off the 2x4. 15 years ago he added on with 2 stories tied into the original structure. Roof trusses were 2' sheathed with 7/16's OSB and strapped with essentially 11/16's thick 1x4. We laid half inch ten test in between the straps but with 3/16's air space the rain makes a lot more noise, which over offices isn't the best. Steel on a residence roof straight over the sheathing with a membrane in between would be the way I would go. Any future foot traffic on the roof, you have better support and better sound deadening.
 
Ive seen steel panel of all sorts applied over many substrates with many different barriers. I would defer to your regions best application method. I have experience with panels over OSB with success. My only recommendation would be to explore 5/8 v 1/2.
 
Osb will not hold screws for long, it will blow off in high wind. Screws need to be an inch in wood. Add fur strips, screw your metal on and be done.
 
(quoted from post at 16:19:05 09/20/21)
(quoted from post at 15:02:22 09/20/21)

Standing seam metal roof is great. All the rest will start to leak at the screw holes in 15 yers. The holes get elongated by the expansion and contraction.

That may be your experience, but not ours.

First let me say, I DO NOT like when nails are used for steel roofing rather than screws. However, a new roof was put on this place before we bought it over 20 years ago. They used nails (yes, with the rubber washers). To date, no leaks.

I've yet to know if a leak from any roof I've installed using screws, and I haven't done a roof in about 15 years.

That said, I agree that a standing seam is superior to exposed fasteners.


kcm, it is my understanding that the expansion/contraction is worse when the metal spans greater distance from ridge to eaves. So larger buildings are probably worse. I used to have the use of an indoor riding arena to pull loaded wagons into if rain was threatening. I had to still tarp them because the metal roof leaked very badly.
 
Check on the warranty. I just put a new steel roof on my house.
I was going to do it myself because the 50 year warranty on the
steel roofing sold at the local big box store was half the price!
But, only if you replaced the screws every year.
If you don't, there's no warranty at all! Who's going to do that?

I would replace any soft wood first. That's structural damage/rot
and it will continue to rot if it's not taken care of.
Do it right, do it once. Unless you're mowing the yard, shaving,
doing dishes, laundry, etc. lol
 
The place I buy my metal from says that is the way to do it they have some that snaps together kind of like standing seam unless you do it like your talking about it they wont even sell it to you
 
(quoted from post at 18:05:43 09/20/21)
(quoted from post at 16:19:05 09/20/21)
(quoted from post at 15:02:22 09/20/21)

Standing seam metal roof is great. All the rest will start to leak at the screw holes in 15 yers. The holes get elongated by the expansion and contraction.

That may be your experience, but not ours.

First let me say, I DO NOT like when nails are used for steel roofing rather than screws. However, a new roof was put on this place before we bought it over 20 years ago. They used nails (yes, with the rubber washers). To date, no leaks.

I've yet to know if a leak from any roof I've installed using screws, and I haven't done a roof in about 15 years.

That said, I agree that a standing seam is superior to exposed fasteners.


kcm, it is my understanding that the expansion/contraction is worse when the metal spans greater distance from ridge to eaves. So larger buildings are probably worse. I used to have the use of an indoor riding arena to pull loaded wagons into if rain was threatening. I had to still tarp them because the metal roof leaked very badly.

Makes sense to me. Larger buildings have larger areas, so more sun's heat likely to cause increased temps over a smaller roof?

I, too, have had to tarp items inside a wood-framed, steel covered pole building. Concrete slab. Ground stayed very dry even while raining. But the steel was simply spanning wooden support. Fast-changing temps would cause moisture in the air to condense on inside of roof and drip down. Only happened when conditions were right. Same thing happens, but is even worse with those tarp-like portable buildings.

I haven't seen a 'lot' of steel roofs up close and personal, but it seems that leakage comes primarily when the fasteners are not installed correctly. Too tight and the rubber washer gets compressed too much; becomes hard and brittle; won't expand when needed. Too loose and the opposite, plus the steel is loose and moves more due to wind; wallows out holes more.

I don't know what the comparison is between a roof where you can put fasteners literally anywhere vs. framing that is 2 or more feet apart. Maybe someone else here has the experience to answer that??
 
(quoted from post at 20:58:53 09/20/21) John - I believe I would try to leave a vapor barrier between the metal and the OSB. Your OSB would likely rot from condensation before too long if there is no room for them both the breath. Good luck - Bob

^^^^THIS. Bob1958 is on the mark. I am not sure what the situation in La is, but with heat/cool and humidity changes, moisture will get trapped in there and rot the wood. So you need an air space. In my area, anyway. Check with the manufacturer. Do you have hurricane codes? That will also affect how you do things. Dave
 
29 gauge is alright over a OSB roof. It's just when you try to put it over just rafters you have to be especially careful walking on it not to damage the metal. Now a metal roof is bad to expand and contract quite a bit. If at all possible I would try to put the screws into the framing rather than the OSB. In just the OSB the screws are likely to get loose and leak. Then the slope of the roof if it's less than a 12/2 pitch I wouldn't use it. With a heavy enough rainfall the roof won't drain quick enough and water can run over the top of the seams. Anywhere near that shallow of a slope I would put a thick bead of gutter and flashing caulk in the seams. Under normal circumstances tacky tape would be good.
 
(quoted from post at 14:45:46 09/20/21) Without going into why

How will 29 gauge residential metal preform bolted directly to clean new half inch OSB and a synthetic underlayment.
IE: No furring strips.

If the OSB is damaged or soft, you either need to replace or put strapping (furring) over it. Do not apply the steel directly over the damaged areas. The other question you have to ask is why was the OSB damaged in the first place? Was it a leak or a ventilation issue?
 
29 gauge is a high strength steel and if bent will kink which cracks it. We get a 24 gauge steel and screw it on the top of the ribs with 2 inch screws. We just put it on over the old shingles if they are not more then about one layer. When I did my roof I had to take off 3 layers of asphalt shingles and left the wood shingles on. One side I took it down to the roof boards and put down that pink folded foam then the steel. We drill the holes for the 24 gauge hard to get the screws to go through good.
 
John
Why not just take the insurance money, hire the job done and return it to original?


The metal roof on my pole barn is extremely noisy when it rains.
 
(quoted from post at 15:09:15 09/20/21) You might need some air space between the steel and the OSB to help keep the OSB from rotting and the steel from rusting on the underside in your hot humid climate.

This post was edited by fixerupper on 09/20/2021 at 12:10 pm.
es on air space (condensation, wet metal, no good way to air dry)..I installed metal over plywood with composition shingle, using 1X4 strips about 18" to 2 ft as best I recall in 2003 and all is well. Yes, plywood back in the 60's vs today's OSB.
 
(quoted from post at 22:52:50 09/21/21) John
Why not just take the insurance money, hire the job done and return it to original?


George
I wish it was that easy.
y roof is 12/12, so that sure helps with leak problems! And why the original composition lasted for 34 years!
 
(quoted from post at 11:35:40 09/21/21) John
Why not just take the insurance money, hire the job done and return it to original?


The metal roof on my pole barn is extremely noisy when it rains.


George, they had a devastating hurricane there. There are tens of thousands of homes needing repair but only thousands of contractors available, so to me it makes sense to do it yourself if you have the capability, rather than allow more rain to further damage the structure.
 
My opinion is that its the best way to do it. Its how I did it on my own house roof except it was existing plywood instead of OSB. Im in CNY where we get lots of snow. Is been 11 years now and I haven't had any problems at all so far and still looks great.
They went the cheap way and put furring strips over the shingles on the roof where I work just a few years ago and I can see waves in the metal now. The shingles were in really bad shape underneath. Plus it noisy when it rains hard. But it was less labor and cheaper and that's what they wanted.
 

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