i've always put the posts in the ground, - - 36' deep according to local code, - - 2' of stone at the bottom, - - a coating of 'fibrated' roof coating on the sides and bottom, - - nails on the sides, - - fill with concrete to about 4' 'shy' of the top.
how deep is the frost line? if your setting deck posts move up in the spring then settle back down as the weather warms, then you have a bad case of frost heave-osis. so how deep is the frost line? in the winter, the ground freezes from the top of the soil downward. the depth of frost
up vote 2 down vote favorite. i am building a deck. how about setting 6x6 p.t. posts down on a concrete footing at 4 feet deep the frost line here and fill with gravel and soil, and then let the posts run high for the railings? this is instead of doing concrete piers and setting posts on them above ground.
outdoor temperatures obviously make a difference, and so does proximity to water. decks constructed near wetlands will have an increased potential for frost heave. the minnesota state building code requires footings to be a minimum of 42 deep in the southern part of the state, and a minimum of 60 deep in the northern part of the state. the diagram below shows the dividing line.
how deep to dig in posts. dig posts or footings to local code requirements or at least six inches below the frost line. always backfill under posts or footings with gravel for proper drainage. in warmer climates you can use premade footings. check with your local code enforcement agency for specifics. wood vs. steel and other footing options
why deck posts should not be set in concrete the photo on the left shows a post set in a bracket that has been mounted to the top of a footer. the photo on the right shows a post that has concrete poured around it, which can lead to a crack like you see here.
the deck post must be connected to a concrete pier if possible using metal connectors and fasteners. how much do decks weigh? the average deck can weigh several tons or over 4,000 pounds.
it's just about impossible to dig deep deck construction post holes without a clamshell digger - maybe i have just forgotten what life was like without one. this tool is basically like two shovels facing each other and connected together, it's easy to work by digging the blades in and then seperating the handles to bring the shovel heads together.
the deck posts connect to the concrete piers using similar metal connection post bases. there are several types of metal post bases, but they all connect to the concrete pier and to the wood post. once again, youll size the metal post base to the wood post that youre using.