What is under a metal roof?

Our metal roof is applied directly onto steel rafters spaced 4 foot apart.

They do not require screws every foot.

I could see any of the previous discussed options.

If you have multiple layers of composite shingles that have all failed, it is possible that they are heavy, their weight plus snowload might be a strain on the house structure.

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farm mom, I highly doubt the metal roof could be nailed onto rafters. Rafters are boards, generally 2 inch thick and run from the top of the outside walls up to the peak of the roof. A sub-standard house roof could have the metal nailed to pirlins that are nailed to the rafters and then the metal roof nailed to that.

ET1 SS, same comment. Your metal roof cannot be fastioned to a rafter, wood or metal. I have seen metal support members run between metal rafters and the metal roof attached to them.

Follow manufactures recommendation on ice shield and drip edge and facia.

I followed the plans exactly.

My house has four arches of griders, at 20 foot intervals, each arch spans 40foot.

Reaching between those girders are:
one horizontal purlin at 7 foot height running along the walls, and
roof purlin/rafters at 4 foot intervals [one along the eave, then another 4 foot in and on until the peak, then identical on the other side].

The roof sheets rest directly on those rafters.

Why do you think this?

We have a roof on our shop (with OSB decking and roofing felt btw) and old fashioned, galvanized roofing nailed through both the roof decking and into the rafters.
I know. I drove the nails.

A neighbor of ours has a machine shed roof (uninsulated) that is standing seam type of metal roofing that is nailed directly to the rafters. Again, it's pretty obvious because when you stand in the shed, you look up and see the rafters, directly under the roofing.

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~*~Erin~*~
SAHM, ranch wife, sub and quilt shop proprietress
the Back Gate Country Quilt Shop

If you have a center chimney and a steep-pitched roof, and install metal, you will never be able to find a sweep willing to work from the top again, which means a big mess inside the house when the chimney needs to be cleaned.

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With all due respect I must disagree.

I was bought a home in Scotland and the seller insisted that he had to teach me how to clean a 'lum'.

You hand a sheet across the opening of the fireplace, with a hole in it's center. The brush goes inside the lum with it's handle poking out through the sheet's hole. All edges of the sheet must be weighted down.

It works.

And it keeps your house clean.

It is most definitely directly on the rafters!!! I have been directly under the roof in the attic and upstairs room. Since the roof leaked, I had to pull the ceiling out and replace it. There is nothing at all between the roof and the rafters.

Rafters run up and down, the sheeting runs across the rafters, and then your tin runs up and down the roof the same direction as the rafters.

Perhaps the problem is one of vocabulary.

My purlin/rafters run parallel to the peak. The last one is the eave.

While the sheets run from the peak to the eave at a slope.

In the song by Simon and Garfunckle, " It's only words and words are all I have....."
If rafters run eave to peak and purlins run the other way, I'm thinking the metal roofing sheets are going from peak to eave, on top of perlins. If I tried to nail metal roofing to rafters, the metal would sway quite a bit in the middle between the rafters, because they are going the same way.

I'm sometimes accused of using the wrong term, but in giving advice, I try to use the correct term, to avoid confusion.

If I told you about the time I kicked a guy square in the heal with the toe of my glove, you might not understand that I meant but and boot.

Sheeting, normally 48 inch by 96 inch is not a rafter, it's sheeting.

When you look at a roof truss, the angle part that meets at the top is a rafter. The horizonal part at the bottom is a joist.
If you have a machine shed roof (uninsulated) that is standing seam type of metal roofing it can not be nailed directly to the rafters. Again, it's pretty obvious because when you stand in the shed, you look up and see the rafters, directly under the SHEATHING. Right? Please tell me that you do not mean to say that you see the underside of the standing seam metal roof above the roof truss (. There has to be either OSB sheets or 2x4 perlins. Can you get back to me on this?

The roof was uninsulated. When standing below it, it is quite obvious that there is no sheathing. The metal roof is visible just above the rafters.

My roof sheets are 48inch by 22foot. They extend from the peak to the eave.

The 'joists' then are spaced 4foot apart, starting one at the eave, and one 4 foot higher up the roof line closer to the peak, and so on.

The 'rafter' the angle part which meets at the peak goes at a slope to the eave then turns are runs down to the foundation. Each of these 'rafters' form an arch shape, 14 foot tall and 40 foot from foot to foot. Our home has four 'rafters' for it's 60foot length, they are spaced 20foot apart [our home is 40 by 60].

The sheets lay on the 'joists' and are screwed in place. I know, I did it [following the directions manual].

Standing on the ground underneath it, when I first hung them, obviously I could see the sheets. I can not now see them, as I sprayed 2 inches of foam on them, then I hung 9 inches of batting and wood paneling.

Our roof sheets are attached at 4 foot intervals onto the 'joists'.

Check with your homeowners insurance on how much more your premium and deductable will increase with the steel roofing before committing to it. While a metal roof will last longer, depending on your fire zoning and carrier it could increase your insurance premium up to 500% because metal roofing increases the likelyhood of an attic fire totally destroying the structure before fire crews can respond much as mobile homes end up going all the way down.

If you dont update your coverage declarations from shingle to steel roofing, your carrier can nullify your policy due to fraud.

300% higher insurance premiums if I had went with a 50 year steel roof after the gravity wave last year was why I opted for a 25 year shingle roof again.

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I think you're going to get what you pay for. My guess is that the Amish guy isn't going to do what's required by code. I just can't believe that you're not required, by code to put that ice shield there to prevent ice dams.

I think you also need to follow Shrek's advice. After all, he's going to be in another movie soon.

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-----DD

I was probably installed over purlins.

By sheeting, you mean roof decking?
In which case, this is assuming you have decking... But why would we assume that? It's not at all unusual for simple roofs to have purlins instead. (or, as mentioned, nothing at all!)

This might indeed be a question of vocabulary.
This is a truss:


These are rafters:

Two completely different roofing systems.

When I say our neighbor's machine shed has the roofing applied directly to the rafters, I mean it's sitting directly ON the rafters. 16" OC if I'm remembering right.
The picture above, with metal directly applied.
No, there does not have to be either sheathing OR purlins. Would it be better that way? Probably. But that's not how he chose to do his roof and it's been working for him for over a decade...

And, as previously stated, when I say our roof is attached through the roof decking, to the rafters, I mean the picture directly above, with OSB sheathing and then the metal roof. The roof is nailed directly through the OSB into the rafters.

PS: For everyone else, since we're talking vocabulary, purlins are the boards that that span the rafters, crosswise usually.

__________________
~*~Erin~*~
SAHM, ranch wife, sub and quilt shop proprietress
the Back Gate Country Quilt Shop

This is interesting.
Our homeowner's policy is actually considerably LOWER because of a metal roof.

__________________
~*~Erin~*~
SAHM, ranch wife, sub and quilt shop proprietress
the Back Gate Country Quilt Shop

There are no purlins in my roof. The rafters are about 2 feet apart - but they vary in distance apart. There is nothhing running across them under the roof. On the underside of the rafter there are pieces running across that the sheetrock was screwed onto. Even these are various lengths and widths. Some are as small as the distance from one rafter to the next, and some run 10ft. Most aren't even straight. It was very much a slap together job. Of course, I didn't realize it when I bought it. My home inspector said it looked like a great house for me.

Same here

When I was considering the covered steel roofing , our fire chief was the one who told me the possible increase in premiums with metal roofing factored in zone rating and how plentiful hydrant water was because ripping through metal roofs required use of K12s instead of fire axes and such. He also said FDs are rated on the equipment they carry on trucks

Sure enough my being in the worse of the fire zone ratings here, metal roofing was not the most economical for me even estimating a normal maintenance reshingle in 20 years at 3 times the cost it was last year.

My neighbor went with 50 year plastic coated steel a few years back and I asked him about his roof after what our fire chief said and he told me that his premium went up while his sister had the same roofing put on her home in a nearby city 50 feet from a hydrant and in first rate fire zone and her fire risk factor didn't change but her roof damage factor decreased and her premium dropped a bit.


Thats why its smart to check before committing to structure changes because there are so many factors taken into consideration when they calculate premiums now.

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