Deck Footings: Why the Part You Cannot See Decides Everything

Every spring, decks in this region get a little less level. The reason is almost never the decking. It is what is holding the posts up.

Water in the soil expands when it freezes and pushes anything above it upward. If a footing does not reach below the frost line, the ground under it lifts each winter and settles each spring, and the deck slowly racks out of square. In our jurisdictions that means digging to the depth the local code requires — and that depth is not a suggestion, it is the whole reason the footing exists.

The ledger board is the other thing worth being fussy about. Where the deck attaches to the house is the single most common point of serious deck failure, and the fix is not more fasteners — it is correct flashing so water cannot sit against the rim joist and rot it from behind, plus the right structural connectors rather than whatever was on the truck.

Materials are more of a preference than a durability question these days. Pressure-treated is the value option and takes stain well. Cedar looks and feels better and costs more. Composite costs the most up front and asks the least of you afterwards — no sanding, no restaining, just washing. Any of the three will outlast a bad footing, which is rather the point.

One practical note: railings and stair geometry are heavily code-governed, and inspectors in this area do look. Baluster spacing, guard height and consistent riser heights are not places to improvise, and getting them wrong means rebuilding a section that was otherwise fine.

Building or rebuilding a deck? Call Montocon General Contractor at (240) 357-7306 for a free written estimate.