Buy oak timber: properties, sizes and applications

Oak is one of the best-known and strongest timber species in the Netherlands: hard, durable and recognisable by its flame grain. It requires a different approach from Douglas fir or pine, especially for fixings. Below are the properties, sizes available from Houthandel Jan Sok in Meppel and the pitfalls that shorten oak's service life.

What are the main properties of oak timber?

Oak is strong and hard, weighs approximately 700 kg/m¹ and falls within durability class 2 (heartwood, 15 to 25 years). It is recognisable by its flame grain and medullary rays. Oak contains tannic acid, moves significantly as weather conditions change and therefore requires stainless steel fixings and room to shrink and expand.

• Durability class 2 (heartwood) - durable, 15 to 25 years outdoors above ground
• Density approximately 700 kg/m¹ - considerably heavier than Douglas fir
• Flame grain and visible medullary rays, especially in quarter-sawn timber
• Tannic acid - reacts with iron; see the stainless steel section below
• Moves significantly - freshly sawn ("green") oak shrinks and cracks as it dries
• Sapwood is not durable (class 5), even though the heartwood is class 2

Where can I buy oak timber in the Netherlands?

Houthandel Jan Sok in Meppel (Drenthe) supplies oak timber from stock throughout the Netherlands: rough-sawn posts up to 200x200 mm, beams, boards, roof decking and half-lap weatherboard. Order through the webshop, by phone on +31 522 851 551 or at the counter at Celsius 10. Collection from Meppel is also possible.

Which oak timber sizes are available?

Available products include rough-sawn posts of 150x150 and 200x200 mm in lengths from 2.50 to 5.00 metres, rough-sawn beams of 70x150 and 70x200 mm in lengths from 3.00 to 5.00 metres, rough-sawn boards of 20x200 mm, planed roof decking of 18x130 mm and planed half-lap weatherboard of 18x180 mm.

Current prices and stock are shown for each item in the oak category. Need other dimensions or longer lengths? Request a quote.

Is oak suitable outdoors and in direct ground contact?

To a limited extent. Oak heartwood is durability class 2 and lasts well outdoors above ground. For permanent ground contact - fence posts, bank revetment and sheet piling - Houthandel Jan Sok recommends azobé, okan or pressure-treated pine in use class 4, or mounting the oak post on a concrete pier.

Oak is particularly suitable for cladding and half-lap weatherboard, roof decking under a canopy, heavy structural beams, and posts mounted on a concrete pier rather than placed in the ground. See the full overview at which timber can go into the ground.

Why must oak be fixed with stainless steel?

Oak contains tannic acid. Contact with galvanised or untreated steel causes blue-black stains in the timber and corrodes the fixing. Use stainless steel screws, nails and hardware - preferably A4 stainless steel outdoors. Pre-drilling is almost always necessary with oak.

For outdoor applications, also treat the end grain and allow for movement: fix cladding boards with one fixing per batten so the timber can move without splitting. Fitting guidelines are available at fitting weatherboard and cladding.

Do you sell oak firewood?

No. Houthandel Jan Sok does not sell oak firewood or fuelwood. Our oak range consists of structural, cladding and roof-decking timber: posts, beams, boards, weatherboard and roof decking. For firewood, please contact a specialist fuelwood supplier.

Oak, Douglas fir or hardwood - which should you choose?

More comparisons: Douglas fir versus pressure-treated timber and decking material comparison. Unsure which species or quantity you need? We will calculate it for you free of charge.