Jim Finlay (Archadeck of Suburban Boston) uses Techno Metal Post drilled helical piers to support a curved deck on grade.
Archadeck workers hand-dig a shallow trench for the grade-level deck support beam.
A Techno Metal Post team maneuvers the helical-pier machine up the stairs to the property.
The Techno Metal Post team works a helical pier post into position. It's possible to work around small stones in the soil by angling the post while drilling it into position.
The installer drills the Techno Metal Post into the ground to at least frost depth, stopping when the drill rig's instruments indicate the specified bearing capacity for the post.
The installer pounds a metal bracket into place onto the top of the helical pier post.
Archadeck carpenter Eric Roberts squares a temporary joist with the deck ledger, as he lays out the location for the deck's in-ground carrying beam.
Eric Roberts sets the carrying beam support bracket height. Bracket height is adjustable, allowing the beam's elevation to be set precisely with respect to the ledger at the house wall.
Roberts establishes a height for the center portion of the carrying beam.
The trench for the beam is lined with filter fabric before being backfilled with large stone. The idea is to allow the trench to stay free from silt and to drain freely. Loose stone will also help to prevent frost action from moving the beam around in winter. The stone is not a support for the beam; instead, the helical piers driven to below the frostline provide the necessary bearing for the entire deck.
Roberts fills the fabric-lined trench with large stone.
The grade beam in place after backfill.
The beam is framed with preservative-treated lumber that is rated for ground contact, as required by industry standards.
