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NeilTheCop 02-06-17 01:42 PM

The roof on my front porch finally gave up the ghost.
After watching the leaks get progressively worse over the years I decided to fix it. Of course in my nativity I thought, just cut out the rotted sections and re-shingle, no problem.
You guessed it, the rot was so bad that I stripped off all the roofing including the pseudo repairs that previous owners had attempted, about 40 pounds of galvanized metal and the same weight in tar sealant.
Having weighted up the cost I decided to replace it all with ribbed, not corrugated metal, now the question.
After taking off the plywood/OSB mixture that was the existing substrate I'm left with the 3/4" high gap where the sheeting used to be, to tuck the new metal under the house shingles. With only a 3/4" vertical gap and the metal roofing ribs being the same height I have no room to add the extra height of a purlin, so can the metal be attached directly to the 2X4 rafters. The 2X4's are on 16" centers and 8' in length, and I intend to cross brace every 24" or so but don't intend to walk on the roof.

DEnd 02-12-17 09:36 PM

Yes you can attach the roofing directly to the 2x4s, assuming the roofing is thick/stiff enough. Check with the manufacturer first. The biggest issue you have is flashing however. The roof wall intersection absolutely needs to be flashed correctly. To do that correctly you will likely be removing wall shingles/siding anyway at that point it's likely not a huge task to make the room you need to add back in the roof sheathing. the positive to that is it will likely lead to a better appearance for the roof ie: much less likely to get dents in it, and a flatter appearance for the roof in general.

jeff5may 02-13-17 07:03 AM

There are lots of "what if's" to consider when planning the reroof. Assuming you will be installing roofing that has the ribs running parallel to the rafters, it could sag between them and look wavy. Snow and wind load capacity are also major considerations.

Besides lowering the ridge beam/ledger board, you could install flat bar or angle over the existing rafters to add horizontal strength. Naturally, each solution has its own set of advantages and challenges. If you live in a municipality where codes and permits are in play, you can always ask the building inspector whether or not a method will be allowed.

NeilTheCop 02-16-17 10:02 AM

Thanks guys.
It's a moot point now because after finally getting everything cleared off I found that the original 2X6 that should be attached to the ends of the house roof rafters had been removed, and the 2X4's that made up the porch had been nailed (badly) directly to them. So I demolished the old porch completely, replaced the 2X6's (which may also account for the house creaking and why my new front door never fitted right no matter how many times I adjusted it) and now have put in new 2X4's with hurricane clips and joist hangers so I'm now able to use the 1X4 purling.
Good news is that I'm now well past the "I wish I'd never started" point.

Again, many thanks :thumbup:

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