Guys,
As part of a larger project, we’re finishing a 12×12 deck, about 3 feet off of the ground. The deck will be supported by a ledger board and two 16 inch round footings (42 inches down). (Plans already approved by the inspector) There is a 50/50 chance the deck will be enclosed into a screened porch at a later date. Any suggestions on how many/location of additional footings/supports we can add now to eliminate or limit additional foundation work that will need to be done if the deck is screened in. The deck is in NJ.
Thanks for any suggestions.
FR
Replies
Our 12x12 deck is designed to be screened in and only has two footings, although the footings are 24"x24".
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Scott,Are they solid concrete or block and are they located at each corner or set in under the deck?Thanks.FR
At first glance, it would seem to me that you would need at least 3 more footings, though it's tough to say without knowing a few things:
If the roof to be built is a shed type, running back to the house wall, or laying up on an existing roof, then I would put one in the center at the outside, cutting the span of the leg bearing the weight of the roof to 6'. I don't think you mentioned specifically how you planned to frame the deck, but I'm going on the assumption that you would have at least a triple 2x12 at the outside, if it's carrying 12' of deck. (personally, I'd put a footing and post at 6' even for the deck without the roof load.)
If the roof is a gable, the I'd put piers + posts at 6' on each side, so the span on each leg carrying the roof is 6', and I'd at least double the joist on each end.
If it's a hip, I'd do both, since the roof will bear on all three.
Bing
I recently done a deck a little larger that 12x12 and I had two triple carriers and a "freeze" board on the house. One triple was mid span of the deck the other at the end. we had to use 6x6 and 10" footing tubes.. We used 6 footing tubes .Its always better to build a little bit stronger, just for this instance, its allot easier to justified elevated cost, verses explaining why it collapsed!!
Edited 11/23/2008 4:54 pm ET by bsh6979
>>>Are they solid concrete or block and are they located at each corner or set in under the deck?
Sorry for the delay.
Ours are solid poured concrete, 24" X 24" X 8" with a 8" sonotube pier which supports log posts under the deck.
Here's a construction pic that might help.
View Image
Scott.
Edited 11/25/2008 9:15 pm by Scott
Edited 11/25/2008 9:16 pm by Scott
In my town, I can't build a screened in porch on a deck with just footings (needs a foundation). Did your inspector know what your future plans are?
No. This was an afterthought. I may go back to him and see what he suggests. Again, we're not certain about the project, but I thought I'd try to limit the amount of extra foundation work if we did. Having said that, I'm not going to do a solid foundation "just in case". I'll have to make a decision and go with it.
Thanks for your help.
FR
In my town, I can't build a screened in porch on a deck with just footings (needs a foundation).
That's odd. I built an addition on top of a second story deck with the existing footings. They were inspected by the Architect and were approved by the town. So, your not allowed to build additions on footing, you need a foundation?
Joe Carola
not so strange around here. So many people added solarium's and screened porches in the 80's that many jurisdictions started requiring full trench footings for all slabs. A problem the inspectors ran into was the homeowner was wishing to enclose the slab, so now you have wall and roof loads on a 12" "rat wall" if even that. As far as the OP, I would advise adding footings per the design of the future screened porch now.
So many people added solarium's and screened porches in the 80's that many jurisdictions started requiring full trench footings for all slabs. A problem the inspectors ran into was the homeowner was wishing to enclose the slab, so now you have wall and roof loads on a 12" "rat wall" if even that.
All you need to do is put footings on the corners and frame the walls on top of microlams that span the whole wall length that are supported by the new footings. This way the walls and roof load are on the microlams and not the slab. I frame this way many times.
Some slabs are strong enough for the walls and the microlams get butted to the top plates and the roof load is supported by the microlams. No reason for full trench footings. It's the same thing as framing on footings and no foundation, you run girders to support the walls and roof load.
Joe Carola
Edited 11/23/2008 8:29 pm ET by Framer