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Deck design...

Posted by Jim -ATS on April 30th, 2000 02:24 AM
In reply to Deck Design by Roger on April 29th, 2000 11:51 AM [Go to top of thread]

I can give you a few pointers, or at least what I like to do, for what it's worth.

The entire deck frame should be built out of actual pressure treated lumber. Cedar will rot.

The precast concrete piers are not my idea of sound construction.

I cast 3' deep concrete post footings with a post hole digger. I give the bottom of the hole a bell shape to increase its holding and soil bearing capacity. Each footing receives a 3/8" threaded J bolt set as close to the center of the post location as possible. A simpson strongtie post connector is bolted to the J bolt, then a 4x4 post is set into the connector. (slam the post onto the bolt to make a mark, then you know where to drill the bottom of the post out to allow it to sit flush in the connector bottom)

The posts should support a beam that runs parallel to the side of the house no more than 7' away from the house. If your deck is going to be bigger than 8', plan on multiple beams and offset the joists on the top of the beams.

The "normal" approach is to have your joists 16"oc, but I believe you end up with a much stiffer deck if you space your joists 12"oc. The extra cost is minimal for the gain in strength and stiffness.

I prefer to use 5/4" clear cedar decking as opposed to 2x4 decking. My reasoning behind that is that the 5/4" does not have the torque ability that a 2x4 does to pull nails out and warp, making it far more likely to behave itself over the long term. In my experience, this theory holds true. The 12"oc joists are further justified by the less brutish decking material.

I find that my prybar works well as a gauge for board spacing. Make it less than 1/4" to prevent heels from getting caught, but do not place your deck boards right next to each other, you must allow for ventilation to prevent rot and mildew.

I use 3/8" bolts through the 4x4 cedar rail posts, and I use a 1" spade bit to sink the heads into the posts flush with the surface. Use washers and lockwashers. Do not notch the 4x4 to bring it into the deck surface. This only weakens the post.

For the rail, I screw a 2x6 clear cedar rail cap to the top of the 4x4's, a clear cedar 2x4 to the deck side of the 4x4's with the 2x6 exactly flush with the top of the 2x4. Your 2x2 cedar ballusters will now screw to the back of the 2x4 under the 2x6, and to the face of the deck rim joist (one screw at the top, 2 at the bottom.) I like to cut the ballusters with a 45* angle cut to give a better look.

Make sure you flash your deck ledger boards properly, I gave specific instructions on how to do that a week ago or so.

Post back with specific questions, and we'll do our best to help.

Good luck!

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