Base plate
A steel plate welded to the foot of a post so it can be bolted to concrete instead of dug in. Moves the weak point of the installation into the slab.
Also called: base plated, bolt down post, baseplate
A base plate is a flat steel plate welded across the bottom of a post, drilled for anchor bolts. It turns a post that would normally be concreted into the ground into one that fixes down onto an existing slab — which is the only option on a finished warehouse floor, a deck, a basement car park or a pavement nobody wants dug up.
The trade-off
A dug-in post transfers load into the ground, which is effectively unlimited. A base plated post transfers it into a handful of anchor bolts and the concrete immediately around them. That concrete becomes the weakest part of the installation, so it has to be sound, thick enough for the embedment, uncracked, and not so close to a slab edge that the fixing can break out a cone of it.
Bolt down is a legitimate detail used on plenty of sound installations. What it is not is a way around bad ground.
Fixings
Anchor bolt size follows the post, the load and the depth available — commonly M8 to M12 for fence post plates, and heavier through-bolts with a sleeve where the plate is carrying real impact load. Sizing is a site decision: the person fixing it is the one who can see the slab.
Base plate products we stock
Frequently asked questions
- What is a base plated post?
A post with a steel plate welded to its foot, drilled so it can be bolted down to concrete rather than concreted into the ground.
- Is bolting down as strong as digging in?
Not inherently — a dug-in post spreads load into the ground, while a base plated one puts it into the anchor bolts and the concrete around them. Done on a sound, thick slab it is perfectly good; done on a thin or cracked one it will pull out.