Heavy Duty Galvanised Bolt Down U Post Support Base Bracket

This heavy duty bolt-down U post support base bracket gives you a secure, surface-mounted fixing point for timber fence, pergola, decking and gate posts onto an existing concrete base, patio slab or footing. Unlike a drive-in or cast-in ground spike, this is a bolt-down design: the flat base plate is fixed with masonry fixings straight onto the surface of cured concrete, while the U-shaped upright cradles and is screwed to the sides of the timber post above ground level.

Manufactured from galvanised steel and finished with a hot-dip zinc coating, the bracket is built to resist rust and weathering in exposed outdoor conditions, giving it a long service life on fences, pergolas, decking frames, gates and other timber garden structures. Raising the post above the concrete surface, rather than embedding it, also helps maintain a clear expansion gap between the timber and the ground below, reducing the risk of rot from standing moisture and letting the wood move naturally with changes in temperature and humidity.

The U-shaped upright is pierced with a row of pre-drilled fixing holes on each arm, so the post can be securely screwed in place from both sides once it's stood square in the bracket. The base plate has its own pair of pre-drilled holes for bolting down to concrete. Fixings (coach screws for the timber; concrete anchors or screws for the base) are not included, so choose fixings rated for your post size and base material.

Two channel widths are available, sized to suit common sawn softwood fence and decking posts: the 75mm size for nominal 3 x 3 inch posts, and the 100mm size for nominal 4 x 4 inch posts. Both sizes share the same 200mm (7.87") overall upright height and 60mm (2.36") base plate depth, with the base plate footprint and steel gauge stepped up slightly on the larger 100mm size to suit the heavier post it carries.

Both sizes are independently assessed for use in load-bearing timber connections under a European Technical Assessment, tested to EAD 130186-00-0603, with each size CE marked under its own European Technical Assessment. The declared vertical and lateral load resistance values (see the Specification table below) are the same for both sizes, useful reassurance for structural garden builds such as pergolas and decking frames.

Key Features

• Bolt-down base plate for fixing directly onto existing concrete, not a drive-in ground spike
• Hot-dip galvanised steel construction resists rust and corrosion outdoors
• U-shaped upright with pre-drilled holes for a secure, two-sided screw fixing to the post
• Raises timber clear of the concrete to maintain an expansion/moisture gap and help prevent rot
• Suits fence, pergola, decking and gate posts
• Both sizes independently load-tested, each CE marked under its own European Technical Assessment
• Available in 75mm and 100mm post channel widths

Specification

*Figures from the published European Technical Assessment for each size. These are structural design values for use by a qualified engineer, not a guaranteed safe working load for general DIY use.

Typical Applications

Because it bolts down onto an existing hard surface instead of being driven or cast into the ground, this bracket suits any timber post that needs to stand on top of concrete, paving or an existing footing rather than be buried in it. Typical uses include:

• New and replacement close-board, panel or picket fence posts standing on a concrete pad, path edge or existing hardstanding
• Pergola, gazebo and garden arch uprights, where the declared ETA load resistance (both sizes) offers useful reassurance for a load-bearing structural build
• Decking sub-frame and support posts fixed down to a concrete strip footing, pad or paved base
• Garden, side and driveway gate posts, keeping the post rigid on the base without disturbing the surrounding paving or slab
• Re-fixing a post where the original timber has failed or rotted at ground level, using the same existing concrete footing rather than breaking it out and re-pouring
• Any timber garden structure where keeping the post clear of the concrete surface (for the expansion gap and reduced moisture contact described above) is preferred to burying the base

Installation Guidance

Position the base plate on your cured concrete base, footing or slab, checking the post location and alignment before you commit to fixing. Mark through the base plate's pre-drilled holes, then drill and bolt down using masonry fixings suited to the base material; for a structural build such as a pergola or decking frame, choose anchors sized with reference to the declared load figures in the Specification table above. Stand the post square in the U-shaped upright and check it for plumb on both faces before fixing, then screw through the pre-drilled holes on both arms using coach screws or heavy-duty timber screws sized to the post. Leave the gap between the base of the post and the concrete surface that the bracket is designed to create; this is there to let moisture drain away and allow the timber to move naturally with changes in humidity, so avoid packing or sealing it. Fixings for both the base plate and the post are sold separately; choose them to suit your post size, base material and expected load.

Order before 2pm Mon–Fri for same-day dispatch from our UK warehouse.