LESLIE: Alright, Cathy from Wisconsin’s got some questions on behalf of her husband. What can we do for you both?
CATHY: Hi, we’re building a deck …
TOM: OK.
CATHY: … that’s going to be 23×12 …
TOM: Wow.
CATHY: … and it’s going to be …
LESLIE: That’s a nice one.
TOM: Yeah.
CATHY: Yeah, well we have a very big house; it’s 28×64. It’s going to be 12 feet high and what his question was, was he wants to use 4x4s or 6x6s. He wants to know which would be better. And how would he do the concrete; to use tubes or …?
TOM: Alright, well, first of all, this is a big, big project and if it’s a deck that’s 12 feet in the air, it’s a pretty complicated project and, therefore, not for the faint of heart nor the average do-it-yourselfer. It’s a pretty serious project and if it’s not done correctly or even during the project it could become very, very dangerous. So I begin with those cautionary words to you, Cathy, and your husband. This is not an easy job.
In terms of the structure, if it’s that tall, probably I would definitely use a 6×6. A 4×4 is going to twist and warp and be very, very twisty by the time that settles in. And you’re going to probably need a lot of them. So I think that, you know, normally, the way I would build a deck that’s up in the air is I would have one side attached to the house and the other side would be supported by a girder; a very healthy girder that runs the entire length. And then the girder would be supported by these very heavy columns and they would be tied into the footings.
Now, in terms of the footings, I think what you’re talking about is something called a sono (ph) tube, which is basically a round concrete form. They’re very convenient to use because you dig out the hole and shove the cardboard tube in there and then you pour the concrete in the tube and that actually becomes the form. And sure, those are nice and you don’t even have to take the forms out. You can just sort of …
LESLIE: No, you leave them in there.
TOM: … leave them in there, cut the surface concrete out …
LESLIE: Yeah, but how much of the 6×6 do you bury below ground? Is it two feet or does that vary …?
TOM: (overlapping voices) I don’t bury any of it below ground. I …
LESLIE: You put the whole thing on top …
TOM: I …
LESLIE: … so you just rest it on the ground.
TOM: I rest it right on top of the footing …
CATHY: Mm-hmm.
TOM: … and there’s a special plate that can bolt them together if it’s an area that there’s a hurricane risk or if there’s an earthquake risk, there’s a way to tie those together. But no, I don’t – I don’t embed the wood into the concrete because that becomes like a hole where the water soaks in and that can cause deterioration even if it is pressure treated.
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