roof over a deck?

[trimmer1569]

I have a deck professionally built by my homes previous owner. it is not connected to the house in any way. it has 4x6 posts set about 1ft away from the back wall of the house. I would like to remove the 1x4 lumber that is currently on top of the structure and roof it . that being said, it must be safe!!!
step one, remove everything but posts.
step two - 2 2x8s stacked on top of the rear posts to add 8" of height and out the load on the beams( which are in concrete footings, not sure of depth)
step 3 double frame the entire front edge with 2x8s
step 4 lay 20 ft 2x6's at 24" oc and use brackets to attach?

DO I NEED A LEDGER BOARD? i would like this roof to be self supported and just next to the home and flashed for proper drainage

step 5 - deck in 1/2" osb and roll on 20lb felt, add asphalt shingles

the deck length is 22ft, width is 16ft

cant attach the pic i want to attach!!!! this would help

try to add some more detail since no pics
post spacing

post 6ft post 10ft post 6ft post on the back and front

the sides are same end posts as front and rear with a mid post at 10ft total lengh os side 16ft putting the mid post off center by 2ft

[Don_P]

You should be able to post a pic now.
What is the snow load?

[trimmer1569]

this is the existing deck, there is no snow load
location dallas texas, we get maybe 1/2 inch of ice every other year one time in winter

[Don_P]

The rafter span table R802.5.1(1) lists maximum clear span for #2 southern yellow pine 2x8's at 24" on center as 15'-10" in a no snow area.

You cannot ledger into the brick but I would attach to the house framing above that. The diaphragm of the roof attached to the rigid house would do alot to brace the structure in the wind. Use hurricane ties at all rafter connections and make sure to strap everything down, this is a kite. Looks like it would require removing a row or 2 of siding and getting a flashing between wall and roof. Minimum slope for shingles is 3/12, 3" drop per foot. I prefer not to go below 4/12. if at all possible.

The outer beams need to be notched into the posts not just bolted on. It passes for me using two 2x10's of #2 SYP. That is not in a codebook table. The girder table allowsdouble 2x12's at 9'-9" span supporting roof and ceiling on a 20' wide building with a 30 psf snow load. The table does not go below that. Your inspector could require engineering for that and may ask for knee bracing or engineering on the entire structure, it falls outside of the prescriptive code so he would be within his rights.

One correction, you started the first row of roof ply with a full sheet, start the next row with a half sheet, then the next with a full, etc, to offset the seams.

[trimmer1569]

thank you don p. for the reply.

a couple of questions?
i could switch to double 2x10s no problem. but that still only gives me 10 inches of pitch over a length of 16 ft. (not enough huh). also i don't beleive a can notch the 4x6 posts for sides due to not over 1/3 post width can be cut out for notch? am i wrong on this. is there a way to safely lengthen the rear posts closest to house to give me more pitch.

should i just switch to r panel or corrugated plastic panels with so low a pitch? i wish they hadn't built this thing completly flat.

i was really trying to build something i could reuse the existing posts as i would have to deconstruct and rebuild the deck to put in like 6x6 posts

[Don_P]

That is not my understanding of the notching provision, but I've been wrong before. Simpson has post brackets that would work,
strongtie.com

I would lose or replace the posts on the rear and use just the ledger or replace them from the deck up to the ledger. If you go that route, I'd review the ledger bolting section in the codebook or the guide in DCA6 in the free download library at awc.org
You could remove a few deck boards back there and have access to replace the posts with taller heavier ones without rebuilding the deck.
It sounds like you want to keep this freestanding, if so I would want some strong bracing, bolted or bracketed, on all the posts.

Other roofing products can go to lower pitch than shingles, you might also lower the front posts some.

[my5sons]

This could easily be accomplished by bolting a ledger to the house like the last guy said. From the looks of the photo, you could easily have a 4/12 or 5/12 pitch by moving the rafter ledger all the way up near the 2nd story window.

If you know a little bit about construction work, you can follow what they did here:

http://video.bobvila.com/m/21319543/framing-the-porch-roof.htm

I didn't do a laminated beam on mine (sandwich a 1/2 thick plywood between the 2x's) I just used constrction adhesive between 2 - 2x10's.