low level deck framing question

Old 04-21-10, 08:10 AM
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Join Date: Apr 2010
Location: USA
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low level deck framing question

HI, I have a deck question, below is some details about my deck and then I"ll explain my question.

I am building a big deck in MN (so I'm digging deep 48'' and mushrooming out to 15'' on the bottom for my frost footings). My deck is using 2x8 joists with 2X10 beams. My deck is 12X18 at one portion and 14X12 at another portion due to a 4' notch in the house, so the deck is 26' total width and either 18' or 12' long depending on what part of the deck you are on.

My question is that from the bottom of my ledger to the ground it's between 12.5 and 15 inches. With my 2X10 beam (9 1/4 inches) that gives me between 2 3/4 inches and 5 or so inches. Then you factor in the footings being 2 inches above grade and it doesn't leave much room for the 6x6 post. So my solution was to poor the cement footings and place the 2x10 beams (2 put together) directly on the concrete footings with some sort of fastener. Is this the best approach? or would you use a 6x6 post and sandwich the beams to the post or use 6x6 posts and put them directly into the ground? Secondly if I do attach the beams directly to the footings chances are I don't get the footings exactly at the right height or exactly level so what material would I use to shim between the beams and the connectors? Lastly what connector would you recommend to attach the beams to the concrete.

Thanks in advance for answering my question.
Old 04-21-10, 04:49 PM
Join Date: Mar 2000
Location: Arlington, WA
Posts: 9,238
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Welcome to the forums.

There are two different ways that you can go about installing the deck that will allow you to get it in.

The first would be to locate the outer beam at the outside edge of the deck (parallel to the wall of the house) and raise it up so that the top of the beam is at the same height as the top of the joists. Use Simpson LU210's to attach the joists to the face of the beam. But given the dimensions that you are using, you'll have to use 2X12's for the joists and dbl 2X12's for the beam. 2X8 joists would be way over spanned at 18'.

The other would be to add a center beam, reducing the joist span, which would allow you to use 2X6 joists sitting on to of either dbl 2X8 or dbl 2X10 beams, depending on your post spacing.

The drawback to the second option of course would be the need for more footings, and given your frost issue, additional footings are going to add a lot of labor and cost to the deck.

As long as your deck is this close to grade, there is no reason to use 6X6 posts. At less than 2' tall, there simply isn't justification for them. 4X4's will work just fine and will save you money.

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