Short answer: A concrete post base keeps a timber post out of wet soil, so Douglas fir or pressure-treated timber lasts much longer. Houthandel Jan Sok stocks anthracite concrete post bases from 12 × 12 to 20 × 20 cm, with M16 or M20 connection, from €23.00, plus Speedmix rapid-set cement from €12.45. prices as of 5 October 2026, incl. VAT.
Concrete post bases in stock
| Concrete post base, anthracite | Size and connection | Price from |
|---|---|---|
| Post base 12 × 12 × 60 cm | M16 | €23.50 |
| Post base 15 × 15 × 60 cm | M20 | €27.00 |
| Post base 18 × 18 × 50 cm | M20 | €29.00 |
| Post base 20 × 20 × 50 cm | M20 | €31.50 |
| Post base 18 × 18 × 10 cm | M20 | €23.00 |
The exact connection type is shown on the product page. The low 10 cm base is not meant to be set deep in the ground; ask us if you are unsure which base suits your job.
Which base for which post?
| Post | Base | Use |
|---|---|---|
| 100 × 100 to 120 × 120 mm | 12 × 12 × 60 cm (M16) | Fence, pergola |
| 120 × 120 to 150 × 150 mm | 15 × 15 × 60 cm (M20) | Pergola, canopy |
| 150 × 150 to 200 × 200 mm | 18 × 18 × 50 or 20 × 20 × 50 cm (M20) | Canopy, carport |
Choose a base at least as wide as the post so no water sits on the edge. Matching posts: timber sizes and posts.
How to set a concrete post base
- Mark out the positions with a string line and check the diagonals.
- Dig down to a firm, frost-free layer; in the Netherlands often 60 to 80 cm.
- Pour a layer of Speedmix or concrete mortar and set the base level and at height.
- Let the concrete cure as stated on the bag before loading the post.
- Treat the bottom of the post (end grain) before fitting it.
Douglas fir on a base, hardwood in the ground
Douglas fir is durability class 3: fine above ground, not in wet soil. On a concrete base the foot of the post stays dry. Hardwood such as Azobé or Okan can go into the ground. Read which timber can go in the ground?
Concrete fence posts and base panels
For a fence, a concrete post is often more practical than a post on a base. Jan Sok has concrete intermediate posts 10 × 10 cm in grey from €29.10 and in anthracite from €38.25, in 190, 280 and 308 cm, plus concrete base panels 184 cm from €21.90. This keeps the timber out of the ground. More on the build-up: timber garden screens and fences.
Kerbs
For edging paths and patios there are also kerbs in grey and anthracite, for example the grey kerb 5 × 15 cm from €3.50 per metre. All bases: concrete post bases and kerbs.
Frequently asked questions
What is a concrete post base?
A concrete post base is a concrete block set in the ground that a timber post stands on. This keeps the timber out of wet soil so it lasts longer. The bases at Jan Sok have an M16 or M20 connection for the post.
Which post base fits my post?
Choose a base at least as wide as the post. As a guideline: 12 × 12 cm for posts up to 120 mm, 15 × 15 cm for 120 to 150 mm and 18 × 18 or 20 × 20 cm for posts of 150 to 200 mm.
How deep should a concrete post base go?
Set the base on a firm, frost-free subsoil. In the Netherlands 60 to 80 cm is commonly used. On soft ground or for a heavy structure, ask for advice.
Do you sell rapid-set concrete?
Yes. Speedmix 25 kg is rapid-set cement for setting posts and small concrete jobs, from €12.45. Standard concrete mortar 25 kg costs €6.60 (prices as of 5 October 2026).
Do you sell concrete fence posts?
Yes. Jan Sok has concrete intermediate posts of 10 × 10 cm in grey (from €29.10), anthracite and coated anthracite, in lengths of 190, 280 and 308 cm, plus concrete base panels of 184 cm from €21.90 (prices as of 5 October 2026). With these you build a timber and concrete fence with no timber in the ground.