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imjazzer 03-25-2012 06:32 PM

Please eyeball my deck/porch framing plan
 
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I am building a deck/screen porch off of the back of our house. Total length is 22''; screen porch half is 12'x12'6", deck half is 15'x9'6 (extra 3' leads to steps). Since the gabled roof of the screen porch will tie into the roof, I was advised to forego attaching the entire structure to the house via a ledger board, and instead design it as a freestanding structure by placing an additional beam/posts near the house (and using lateral bracing where needed).

In designing this beam, I decided to have its end posts stand 1' inside the side rim joists, whereas the other beams are flush with the front rim joists (one at 12', the other at 15'). In order to maintain two equal bays on the sides of both the deck and the porch, I've also added posts that are flush with the side rim joists. My aim is to render the beam closest to the house somewhat invisible. I will likely add some kind of skirting that will span the posts that are flush with the rim joists.

Does this only make sense to me?

Additional info:

piers/footings: 10" sonotube atop 20" square footing (per local code)
posts: 6x6 PT
beams: 2-2x12s, notched into posts
joists: 2x8s, 16" 0.c., sitting atop posts

Thanks for your help!

Gary in WA 03-25-2012 08:02 PM

Compare your footings, spans, cantilevers, and beams to this: http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf

Your windows, now on the deck may need to be tempered glazing, framing under the roofed structure needs better support, piers within 5' of house basement require same elevation, it will all show on your approved plans when you get your permit. Need that for your H.O. Insurance carrier and when you sell....

Gary

AndyGump 03-25-2012 11:22 PM

What is the purpose of the beam so close to the existing house? It is only like 32" away from the house connection.

Frankly it looks like there is a lot wrong with your plan.


Andy.

imjazzer 03-26-2012 12:56 PM

It is a freestanding structure, there is no ledger board attached to the house, so the purpose of the beam closest to the house is structural. It is sited where it is to account for both the post footings and the house foundation (local code says that if the beam/posts are within 5' of the house, footings must be at the same elevation as the house foundation). Also, it makes the joist span just under 12'2", enabling me to use the 2x8 joists @ 16" o.c.

You say "there is a lot wrong" with my plan. It would be more helpful if you provided some information.

If this were a a basic rectangular deck or porch--or if I were using a ledger board--my task would be a lot more straightforward. As it is, I am trying to provide the most efficient and suitable support system for a combination deck and porch (freestanding) of two different dimensions.

Any insights?

sixeightten 03-26-2012 02:05 PM

Who advised you not to attach a ledger board to the house? And why?

imjazzer 03-26-2012 02:45 PM

That advice came from a plan reviewer with local county permitting services. One reason given is that where I live, the bolts on the inside of the ledger board-to-house band board connection must be visible for inspection, and in my case that entails opening up the floor nearly the entire width of the house. The other reason he gave is that since the entire structure would be self supporting, it would be safer.

Gary in WA 03-26-2012 11:09 PM

I don't think the double joist under the left side of the screened porch will carry the walls, 1/2 the roof and snow load of the structure with 9' span.

Did you compare the Deck Guide to your plan?

Gary


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