Here are some tips to secure your deck.
Before you mix and pour the concrete for the footings, decide how you'll want to attach the 4×4 posts to them. Generally, steel connectors, available from lumberyards and home centers, are the strongest. Like the 4×4 posts themselves, they should be set at least 6 inches above the ground, because continual contact with ground moisture will otherwise prematurely rust the connectors and rot the posts. Raising the footings above grade level also lets connectors and posts dry quickly. Always use rot-resistant (pressure-treated) wood for support posts or the heartwood of redwood or cedar. With pressure-treated wood, look for a rating of at least .40 (ground contact); .60 or foundation grade, which is best.
Although it's accepted practice in the construction industry to set supports directly into the ground like fence posts, doing so will accelerate rot and make it more difficult to replace rotted members.
Always build footings at least 6 inches above ground so water is able to run off. If the footing is wider at the top than it is at the bottom, it will let frost catch its sides and heave it upward. Shape the holes for your footings so that they're wider at the bottom than the top.
The Reader’s Digest Association, Inc./GID
Decide how you’ll attach the deck’s posts to the footing before pouring the concrete.
