Minimum roof slope for screened porch?

Blaze

Blaze

The Jeeper Reaper
Joined
Aug 9, 2005
Location
Wake Forest, NC
The deck at my house is horribly built. Whoever did it put it right up against the threshold and it has entrained water and is rotting out the back doors. My wife wanted a screened porch anyway, so I'm going to tear down the existing deck and build an enclosed porch. I had the contractor that helped me finish off my upstairs come by and quote me putting a roof over the area so I can build a deck on to it, but he was telling me with the minimum required roof slope they would need to cut into the existing roof and do all this structural stuff and all.

With the layout of my house and deck, I can get away with at least a 2/12 slope, which seems to be what is the minimum for an asphalt shingle roof from what I can find in the code books I have found. This would allow me to tie in to the wall of the house and build it so it meets up with the edge of the current roof.

Can anyone give me a good answer? And does anyone in the Raleigh area want to build a roof for me? :lol:
 
2/12 is the minimum but I never see shingles on anything less than a 3/12. If you go 2/12 be sure to use ice/water shield or a similar type of underlayment.

Not sure how inspections work there but here, you'd need a good set of plans drawn up for county approval first.

No advice for finding a contractor in your area, other than asking a local 'real' lumber yard for some names.
 
I'll look, but I MIGHT be able to get a 3/12 slope if I set the joists on top of the back wall of the house instead of a ledger board on the back wall.

We would need framing plans to do it. I can take care of that though.
 
You can do shingles on 2\12 with double layer underlayment, I think there needs to about 19" overlap on second layer if that makes sense. I've got two low slope roof on my house that i did this with. Not sure of the pitch but no problems as of yet.
 
Low temp ice and water and good underlayment no matter what you do.

Most shingle manufacturer have install directions for 2:12 on the back of the bundle.
 
Rather than doing a shed, do a ridge and gable. 2/12 is too shallow for asphalt shingles.
 
The only way I would use shingles on 3 or less /12 is to run ice and water on the whole thing. Still not ideal. I would try to get the pitch to at least 3/12
 
What's the slope of the existing roof, if they're joining at the edge? That slope transition is a good place for snow to collect and ice dams to form, which is just as likely to damage your existing roof above the slope transition as it is to damage the shallower slope porch. The porch roof is just a porch roof, the main roof is the more important part.
 
Why not overframe into the existing roof to get a better pitch. Would mean use of a little more shingles but would be better in the long run.
 
jyaks said:
Why not overframe into the existing roof to get a better pitch. Would mean use of a little more shingles but would be better in the long run.
Click to expand...

This is what we were looking at last night. We were looking at it and decided that we are going to go a little more in depth than just an enclosed deck and actually build an expansion on the house back there that will have a foundation and all. The roof has a weird kick out over the dining room that I was never crazy about, so we'll be cutting into the roof just above that and will be able to get close to a 5 or 6/12 pitch.

Puts back our timeline quite a bit, but it will be a lot more what we want.
 
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