# Putting steel on uneven roof



## fishhead (Jul 19, 2006)

I was talking to my insurance agent and he recommended replacing my shingles with steel the next time I redo the roof.

My roof sags a little, maybe 8" and the bottom edge bows in 4-6".

I can just create a new roof line at the bottom and let it overhang but I'm wondering about the sag. Can steel be put on a sagging roof?


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## simi-steading (Sep 27, 2012)

This might be the time to replace everything that is bad... If you have to pull off the old shingles and decking, you might as well replace the ridgebeam and any bad rafters... 

But then I start wondering if your walls have sagged too, causing the lower edge of the roof to sag... If that's the case, then you have bigger issues than a roof...


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## Bearfootfarm (Jul 13, 2006)

> Can steel be put on a sagging roof?


It could be, put it would be a foolish thing to do.
You have some structural problems that need addressing first, and I'd bet they go all the way to the foundation


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## fishhead (Jul 19, 2006)

There aren't any structural issues with the walls or roof. It's just sagging from age, being underbuilt or possibly being built that way to begin with. The roof bottom line was built that way

I should have been more clear but the fascia goes in towards the center of the house not sagging down. It was that way when I bought it in the late 70's and hasn't changed.


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## simi-steading (Sep 27, 2012)

Huh? built with a sagging roof line???? 

I'm working on a house now that has a rotted foundation beam.. the wall has sunk around 4 inches or so, but I can't see a sag in the roof. I would expect to see one though.. so that's why I can't believe your house would have been built like that... 

Usually when you see a roof sagging, if it's at the top, it's usually because the ridgebeam is too thin, or the rafters are spaced too far apart.... If it's at the edge of the roof, it's usually because the foundation has given, and the walls are sagging in the middle. Or it could be the top sill has rotted and allowed the rafters to settle... Could be a big handful of things causing a sag.. .

You have any pictures?


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## Lilith (Dec 29, 2012)

In these parts, there are a lot of structures built with a "sagging roof" appearance. They were built that way to direct watershed when snows melt and for decorative purposes. I have put metal roofing (steel, aluminum, and tin) on roofs like this quite often. I do highly recommend having a knowledgeable and trustworthy contractor inspect your roof joists and perlins to make sure the roof was in fact designed this way and is not sagging from heavy loads and decay. This can often be done from an attic or crawl space before you begin tearing off your shingles. Sometimes, a sagging roof-line can be fixed with a few new joists and OSB sheeting, but sometimes it is cheaper and smarter to remove the entire roof and replace with engineered trusses. 
Long story short, it is possible to put steel on this type of roof, but have a contractor look at it first and make sure you are not just hiding a disaster waiting to happen.


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## simi-steading (Sep 27, 2012)

Well ok then.. that's a new one on me... Only thing I've ever seen with a roof built with an intentional sage was a hobbit house or Dr. Suess home...


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## fishhead (Jul 19, 2006)

I weigh about 200 lbs with all my clothes on and I don't feel any significant amount of give when I walk on the roof. Most likely it was just underbuilt and age is catching up with it.

It sounds like it's no problem to put the steel on it even with the sag.

Thanks.


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## fishhead (Jul 19, 2006)

I think the same person who built the house also built the 2 car garage.

The garage roof was constructed of just the diagonal pieces that run from the top of the wall to the peak with no horizontal piece to tie the walls together except one in the middle. How it withstood the heavy snows we had in the 70's without spreading the walls is beyond me.

I ended up running a cable from one wall to the other with a come along used to pull the walls together to lift the roof line 3-4". Then I ran horizontal 2x4's from one wall to the other and put those short diagonal pieces between the horizontal 2x4's to the diagonal pieces to make the "W". And instead of removing the cable I just clamped the loops and left them in place for extra strength.


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## jwal10 (Jun 5, 2010)

How many layers of shingles? How steep is the pitch. The agent may be suggesting the metal because it will be lighter and he knows the roof cannot support another layer, needs all torn off and a metal roof is many times cheaper to insure as it is fire retardent. Also, is the sag at the ridge, in the rafters, or both?. A metal roof can displace the weight over the entire roof to minimize future sagging. Another possability is the metal roof will let the snow slip, especially on a flatter roof, shingles may be holding the snow, if a lot of snow builds up it is stressing the roof....James


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## fishhead (Jul 19, 2006)

There's just a single layer of shingles. I removed the previous layer

The agent has never seen my house.

The sag is most noticeable in the middle of the flat between the edges and ridge and bottom edge. If steel is lighter it would take some weight off it but I wouldn't expect it to rebound.

Is the steel screwed down to touch the roof or is blocking used to reach the steel?

The shingles are still good so I don't have any plans on doing this in the immediate future but I'm trying to think ahead.

Also I'd like to predrill the holes with the steel stacked so that the holes line up but I'm not sure they would if I have to bow the sheets a little although the next sheet would be bowed just as much.


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## fishhead (Jul 19, 2006)

simi-steading said:


> Well ok then.. that's a new one on me... Only thing I've ever seen with a roof built with an intentional sage was a hobbit house or Dr. Suess home...


I have yet to find anything that is either plump, square, level or uniformly positioned yet and I've gone through most of the house. I think most of the work by the builder(s) was done through the fog of wearing beer goggles. I think the cement in the basement was done with a wheelbarrow and smoothed with a flat shovel. Most of the joints in the basement blocks were scraped flat instead of being struck. Some weren't with globs of concrete hanging out.


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## Bearfootfarm (Jul 13, 2006)

Probably the best way would be attach boards to the roof, then attach the metal to those boards with screws.

Dont predrill any holes
Just use self tapping hex head screws with washers


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## fishhead (Jul 19, 2006)

Hopefully I will sell the house and move before the roof needs redoing. That way I will only have to do the new roof on my next house although this one might be good for practice.


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## Bearfootfarm (Jul 13, 2006)

> this one might be good for practice.


 Don't "practice" on something you plan to sell
Practice on a barn or shed


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## fishhead (Jul 19, 2006)

I'm not worried that it would leak. It might just look a little out of square but the rest of the house is off so that won't be an issue.


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## Ky-Jeeper (Sep 5, 2010)

My home has some sag. Jacked up and added support in the areas needed. Lay new boards across your roof and shim the low areas up then attach your new metal. A complete tear off wasn't in the budget and time didn't allow it. No issues what so ever. Another proof in the pudding was my buddies stand alone garage was in a bad shape. He done the same thing years ago. Him and me are truly satisfied. Both stays cooler in the summer with that air gap.


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## Lilith (Dec 29, 2012)

I didn't figure there were a lot of roofs across the country that have built in water drainage. I live in a high mountain desert, and have seen a lot of things you don't normally see other places because of the lack of water. On the bright side, if you can get water where you want it here, almost anything will grow.


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## fishhead (Jul 19, 2006)

Ky-Jeeper said:


> My home has some sag. Jacked up and added support in the areas needed. Lay new boards across your roof and shim the low areas up then attach your new metal. A complete tear off wasn't in the budget and time didn't allow it. No issues what so ever. Another proof in the pudding was my buddies stand alone garage was in a bad shape. He done the same thing years ago. Him and me are truly satisfied. Both stays cooler in the summer with that air gap.


Don't you run the risk of bending the metal if it isn't supported underneath?


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