Deck Foundations - Piers & Footings

Footings are a crucial component in deck construction as they offer a solid foundation to support the deck. The deck design determines how loads are transferred from different sections of the deck to concentrated points of contact with the ground. The more footings your deck has to distribute the total load the less weight each footing will need to carry. Footings take the heavy load of the deck from the surface of a support post over a larger surface of soil so the ground can adequately support it. Without footings deck support posts can sink into the ground under the weight of the deck. Footings also have to be installed lower than the frost line to prevent the deck from moving when the soil freezes in the winter. A pier is used as an upright support to connect the buried footing pad to the structural post above grade. The soil conditions and the climate will determine the size and depth of your footings.

Building laws require frost footings to be installed for all decks that are attached to a house in most climate zones. These footings are inspected to make sure they are capable of supporting a deck and will resist damage from frost. Because footings are installed under ground they will have to be composed of materials that won’t decay. Usually footings are made out of concrete with reinforced steel that helps keep the piers from cracking. The footing size depends on the weight of the structure and the soil type. If you want to be completely certain of your details you should contact an engineer. If you have had a soil test on the property and have the barest of sketched plans for the deck a professional could give you a legally-binding recommendation.