Decks, Patios, Porches and Docks - how to put decking over existing slab and dirt
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jrwbfree
05-16-04, 05:19 AM
I am helping a friend who has a patio 8’8” square. About 6.5’ is under roof and has a rough slab poured. The rest is dirt. It is not used at all. But she hates the way is looks. She would like it to match the decking on the other side of the house. It was done in 5/4 x 6” fiberon planks. There is approximately a 5.5” vertical drop from the interior floor to the uneven slab. The walls are stucco covered masonry brick. My thought was to place 2 x 4 pressure treated ledger boards on all 4 walls. And space the joists at 10” oc with a double joist bolted together down the middle. That way there is a small air gap between the wood and the slab and the gap allows for its unevenness, but it would still give about a ¾ inch drop from the interior floor to keep water from blowing in. She would like the planking done on a diagonal. And I was planning to use #10 x 3” coated screws that are predrilled and countersunk. Does that sound like it will work? What size bolts and spacing should I use for attaching the ledger to the walls? Do you have any other ideas for the framing that might be easier and/or cheaper? Thanks for your help.
Homebuilt44
05-16-04, 10:29 AM
JRWBFree
The way you explain this is about the best way to do it. Rember to support the deck in the middle and edges in the dirt area with PT (pressure treated) post 4X4 work well cut below flush and a top cut L pocket for the 2X4 rest on the post work well for bounce. Lag them in with 2 or 3 of the #10 X 3" or #8 X3" screws for lagging posts.
#10 or #8 X 2 1/2 screws for screwing down the deck are the standard. 5/16" X 3" or 4" lag bolts on the ledger boards spaced on 16" centers will work great.
A #10 screw will hold apx. 100 lbs. of sheer weight but only apx. 50 lbs of pull weight. Pull meaning as if it were being pulled out of its hole. The 5/16 lag bolts will hold 300lbs or more sheer and 200Lbs of pull and are more solid for ledgers.
Doubleing the amount of screws in the ledger will give similar results but is not cost effective. lags are about 7 to 12 cents a piece @1 per 16" and good deck screws are about 3 to 7 cents a piece @ 2 or 3 per 8" see the costs? thats to = holding power I think you will be happier with the lags.
Remember to dig down about 1' and kwikcrete in the posts in the dirt area so they dont move. the posts shouldn't be more than 3' apart for down pressure resistance (bounce). Walk the frame and bounce on it before decking and cure any soft spots with a post.
10" or 12" centers on your 2X4 joists and band joists are fine with 5/4 boards narrow is better. This should look wonderfull and be very sturdy when your finished.
Hope this helps :)
The way you explain this is about the best way to do it. Rember to support the deck in the middle and edges in the dirt area with PT (pressure treated) post 4X4 work well cut below flush and a top cut L pocket for the 2X4 rest on the post work well for bounce. Lag them in with 2 or 3 of the #10 X 3" or #8 X3" screws for lagging posts.
#10 or #8 X 2 1/2 screws for screwing down the deck are the standard. 5/16" X 3" or 4" lag bolts on the ledger boards spaced on 16" centers will work great.
A #10 screw will hold apx. 100 lbs. of sheer weight but only apx. 50 lbs of pull weight. Pull meaning as if it were being pulled out of its hole. The 5/16 lag bolts will hold 300lbs or more sheer and 200Lbs of pull and are more solid for ledgers.
Doubleing the amount of screws in the ledger will give similar results but is not cost effective. lags are about 7 to 12 cents a piece @1 per 16" and good deck screws are about 3 to 7 cents a piece @ 2 or 3 per 8" see the costs? thats to = holding power I think you will be happier with the lags.
Remember to dig down about 1' and kwikcrete in the posts in the dirt area so they dont move. the posts shouldn't be more than 3' apart for down pressure resistance (bounce). Walk the frame and bounce on it before decking and cure any soft spots with a post.
10" or 12" centers on your 2X4 joists and band joists are fine with 5/4 boards narrow is better. This should look wonderfull and be very sturdy when your finished.
Hope this helps :)