Screw-on post bases are made to fit standard square timber posts, most commonly 70×70 mm, 90×90 mm and 100×100 mm. The internal socket or U-bracket should match the post's cross-section, so measure your post before choosing. Adjustable and U-shaped models offer a little tolerance, while fixed-socket bases need a closer match.

Yes, bolt-down post supports are typically made from hot-dip galvanised steel, which resists rust and makes them suitable for permanent outdoor use. The zinc coating protects the base against rain, frost and ground moisture. For coastal or highly exposed sites, a heavier galvanised or stainless steel option gives extra corrosion resistance.

A screw-on post support is fixed to concrete using expansion bolts or anchor bolts through the pre-drilled holes in its base plate. Mark the hole positions, drill into the concrete with a masonry bit, insert the anchors and tighten the bolts, then fit the timber post into the socket and secure it with coach screws or bolts. Always fix into sound, cured concrete at least 100 mm thick for a stable hold.

Fixings vary by model: many screw-on post supports include the coach screws or bolts for fastening the timber post, but the anchor bolts for fixing the base into concrete are often supplied separately. Check the product description for what is included. GeZu Impex lists the pack contents and recommended anchor size for each post base so you can order the right fixings together.