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Concrete Post Bases
Concrete post bases are precast black plinths that hold timber posts upright and clear of the ground, for pergolas, carports, canopies and garden structures. Choose a footprint of 150 mm x 150 mm, 180 mm x 180 mm or 200 mm x 200 mm, in 100 mm tall versions for fixing onto paving or a slab and 500 mm to 600 mm tall versions for setting into the ground. Each has an M20 threaded fixing. Stocked in our warehouse and delivered across Ireland.
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Concrete Post Bases for Sale in Ireland
A concrete post base is the foundation that keeps a timber post dry. Burying a post straight into soil or concrete lets water wick up its end grain, and the timber rots from the inside while still looking sound. A precast concrete plinth solves that: the base goes into the ground or onto a slab, and your post is bolted on top, clear of standing water with air moving around its foot.
It also makes life easier later. If a post ever needs replacing, you unbolt it and fit a new one, rather than breaking out a footing or lifting a patio. The black finish sits quietly in most gardens and suits modern pergolas in oak posts and beams or Douglas fir posts and beams.
Concrete post base sizes
Pick the footprint to suit your post, then the height to suit the surface you are building on. Every base has an M20 threaded insert for the post fixing.
- Low base: 100 mm tall, in 150×150 mm or 180×180 mm, for fixing onto an existing concrete floor, a solid slab or strong patio tiles, where you can’t dig a footing.
- Tall base: 500 mm tall, in 180×180 mm or 200×200 mm, set into the ground for new pergolas and garden structures on soft ground.
- Extra tall base: 600 mm tall, in 150×150 mm, a straight concrete pillar for heavier applications, such as roofed canopies on oak or Douglas fir uprights.
Most bases come with a stainless steel height adjustment plate, which lets you fine-tune the post after the base has set. Check each product page for what is included. The straight sides of the tall bases make them easy to level and line up along a wall.
Post bases vs pole holders and connectors
A concrete base is the most solid way to stand a square post, with real mass under it. If you are fixing to an existing slab and want a slimmer look, our cast iron pole holders bolt down and cradle the post in a flat footrest. At the top of the post, post connectors join the beams to a 150 mm post without cutting joints, and concrete screws fix into masonry without plugs.
Installing a concrete post base
Getting the bases level and in line is the part that decides how the whole structure looks. Work through each base in turn:
- Dig a foundation hole below the local frost line for the tall bases.
- Bed the base in wet mortar or fresh concrete.
- Check level and alignment against a string line before anything cures, and keep the spacing between bases equal.
- Once the base is solid, bolt the stainless steel adjustment plate onto the M20 insert.
- Fix your post to the plate, using the slotted holes to bring it exactly plumb.
Looking after your posts and bases
The black concrete and the stainless steel plate need no maintenance at all. The timber above them is where the care pays off. With the end grain kept dry by the base, a coat of oil on the posts every two or three years keeps the colour and helps the surface shed water, so the whole structure stays looking new. Choose one from our exterior oils and stains. A flexible exterior sealant around the base joint tidies the line at ground level if you want a neater finish.
See the rest of our outdoor timber hardware for everything that goes with your posts.
Frequently Asked Questions About Concrete Post Bases
What sizes of concrete post base do you have?
We stock 150 mm x 150 mm bases at 100 mm or 600 mm tall, 180 mm x 180 mm at 100 mm or 500 mm, and 200 mm x 200 mm at 500 mm. All are black with an M20 screw fixing, and most include a stainless steel height adjustment plate.
How do I install a concrete post base?
Dig below the frost line, bed the base in wet mortar or fresh concrete, and check level and alignment before it cures. Then bolt the adjustment plate onto the M20 insert and fix your post to the plate. The 100 mm tall bases fix onto an existing slab or strong tiles instead.
Can I adjust the post once the base is set?
Yes, on the bases supplied with the stainless steel adjustment plate. Its slotted holes allow fine adjustment for plumb, which helps when lining up a run of pergola posts.
Can I use a concrete post base for a pergola?
Yes, that is what most customers use them for. The base keeps the end grain of each pergola post dry and clear of the ground, and the tall 600 mm version suits heavier structures such as roofed canopies on oak or Douglas fir uprights. Pair them with our post connectors at the top.
Do concrete post bases need any maintenance?
No. The black concrete and the stainless steel plate can both be left as they are. The timber post above is what benefits from care: a coat of exterior oil every two or three years keeps its colour. A flexible exterior sealant around the base joint gives a tidier line at ground level.