Shed roof screened porch

Brown Dog · 07-06-2008, 04:24 PM

Looking to add on to my house. Just a basic screened porch on a concrete slab, 4x4 posts, etc. A few questions though:

1) Can I just cut through the existing slab and pour the required number of "footers" instead of cutting a whole section out? I live in SE N.C. so frost/freeze is not an issue. Also, the outboard end is the only side that needs "footers" to carry the weight of the roof, correct?

2) For the ceiling joists, can I raise them off the top plate so as to add more head room? Collar ties would perform the same purpose only further up the slope, right? Again, the main goal is to gain maximum head room while keeping an 8 ft. outer wall height.

Any help is appreciated.

CarpenterJim · 07-07-2008, 04:04 PM

Can you get to the outside corners of the slab, if so, dig down from the outside & pour your footer under the slab then just cut through the slab for the posts to sit on your new footer. A Core Drill will be a safe option to use to keep from bustin' out the slab.
As for the head room, why can't you just raise the wall height? Is slope a factor? You really need AT LEAST a 4/12 pitch.
I don't follow you on the "collar ties" if you are making a SHED roof??? Collar ties are used on a "gable" roof to keep the rafters from doin' the "split" so to say.

Brown Dog · 07-07-2008, 04:21 PM

I'd like to maximize the head room since it looks like I'll only be able to build out to 10 ft. There is a second story window that bottoms out at 134". I figure 3.5/12 roof will suffice and may ice/water shield the roof decking before shingling. Let me ask another way: with a shed roof, or any, are the ceiling joists necessary? Again, if I could just put T&G on the bottom of the rafters, that would be best!

If the ceiling joists are/were necessary, that's why I proposed moving them up a little to then give the appearance of a "gambrel" roof inside.(hence the collar tie idea)

Clear as mud, right?

CarpenterJim · 07-07-2008, 05:27 PM

No, you do not need ceiling joists on a shed roof. With it being under a 4/12 I'd suggest that you use a metal roof instead of shingles.
Oh yeah, I see what you were talkin' about now with using the "collar ties" to simulate a gambrel. Good idea.