Replies

1. 
   EricGunnerson | Aug 29, 2008 10:26pm | #1

   The footing design is going to depend on the climate conditions and what your building department wants. Where I am we don't get much of a winter and their preferred method is a 12 x 12 x 12 footing at ground level. I did one like that and embedded a saddle connector (u at the top to grip the post/beam, tube with pieces out the side to go into the concrete) in the footing concrete. Easy to do, very solid.

   Your building department may want rebar in the footing - mine did.

   Once you get above ground, you can use posts to support the deck. Some people prefer to use concrete cast in tubes but that's a fair bit more expensive.

1. 
   windermere | Aug 29, 2008 10:58pm | #2

   Thanks for the info. Still not sure whether I can source builders tubes and big foot in the UK.
   Most building codes ask for footings to be below 400mm to prevent frost heave on a rubble base.
   Still looking for best method to use.

1. 
   Marson | Aug 30, 2008 12:33am | #3

   Well, you don't have to use tubes and bigfeet, even if you have to go below frost. You can easily build your "tube" out of lumber, and form a spread footing on the bottom. This is how it was done before sonotubes were around. I did this very thing once while building at an historic site. I formed the bases (4x4 as I recall), and propped the column (12"x12") on top and poured it all in one fell swoop. One nice touch is to build your column out of 1x, and add chamfer strips to the corners. Eliminates the unsightly sharp corners of a square column. The details as far as depth, "rubble base" etc. are up to your local building department.

2. 
   Sasquatch | Aug 30, 2008 12:50am | #4

   Dig six or eight holes 36" deep with a post hole digger.  They will be two rows of three like the end points and intersections of a capital H.

   I am assuming here that the deck will be pretty close to the ground, since you did not specify that.

   Based on that, I would recommend that you build the deck free-standing.  Otherwise, (if it is a tall deck) you will need to attach the deck to another structure.

   Then, assuming you will build free-standing, get six Simpson post anchors, the kind you nail to the bottom of a 4X4 and stick into the concrete, or just stick the posts a couple of inches into the concrete.

   I like to design my joists and posts first, connect them, and then stabilize them over the holes, using lumber or stone scraps to level and support them.  Then, I mix the concrete and pour it in the holes.  Wait a day or two, and then build up the rest of the frame.

   If you attach the framing members wisely, the posts will be stable.  In other words, for the deck to move, all six posts would have to move at the same time.  Since they will be individually secured, this is highly unlikely unless you plan to have twenty people line-dancing on the deck.

   If the deck is raised more than two or three feet, the principles are essentially the same.