deck post question
Agreed on the depth question. The only place to go and get information on the minimum depth is your local building official. This is always where to go when you have your drawings for your permit. There is nothing wrong with exceeding the code, since it is only the least you have to do and not necessarily what is best in the long run. Don't try to sell the house in the future wothout a permit or you could have a messy situation.
Do not waste your money on fiber reinforced concrete. You do not need it and it is easy to make a mistake with. All reputable fiber cement is made with the proper fibers. There are many types such as alkalai-resistant glass (the glass does not deteriorate with age), polypropelene, steel, etc. It is a good product, but you don't need it.
The best way to do your support is to auger or dig a hole to or deeper than the minimum depth. Insert a Sonotube (coated cylindrical cardboard form) - size will depend on whether you have 4x4 or 6x6 posts. Fill with 3000 psi concrete (normal strength) and then insert a galvanized steel attachment (Simpson?) that you attach your wood posts to. Brace the structure according to the design or it could collapse with a good load and a little wind or vibration. Avoid a ledger attached to the house unless you want to remove siding, use a PT ledger, bolt through the rim joist and install through bolts.
If you use tubes, you will end up using less concrete and have sufficient strength down below any frost. It is easy to estimate the amount of concrete so you can just get as many bags as you need and not have a pile of sand and extra bags of cement left.
Last edited by concretemasonry; 11-28-2006 at 08:18 PM.