Planed Douglas Fir Post – Sections 70x70mm to 140x140mm, Lengths 200cm and 240cm

This planed solid Douglas fir post is a square-section piece intended for load-bearing structures: pergola, carport, garden shelter, fencing, raised terrace. Available in 4 sections — 70x70mm, 90x90mm, 110x110mm, 140x140mm — and in two lengths: 200cm and 240cm. The piece is delivered untreated, ready to be protected according to its use and exposure.

The planed Douglas fir post is machined on all 4 faces — smooth surfaces and sharp edges, precise dimensions. Air drying, a natural method, preserves the mechanical characteristics of the wood and avoids internal stresses that can cause excessive cracking. These posts are suitable for exposed outdoor structures: pergola, carport, raised terrace.

Main features

Key points

• ✓ 4 sections available — 70x70mm, 90x90mm, 110x110mm, 140x140mm
• ✓ 2 lengths — 200cm and 240cm, cutting possible on site
• ✓ Planed solid Douglas fir — class 3 — natural resistance, outdoor use away from direct soil contact
• ✓ Air dried — natural method preserving the characteristics of the wood
• ✓ Untreated — to be protected depending on use and exposure
• ✓ Sold individually

Which section to choose?

The choice of section depends on the height of the post, the load to be supported and the spacing between posts:

• ✓ 70x70mm — small light structures, single-pitch carports, fencing
• ✓ 90x90mm — standard pergola, garden shelter, terrace up to 3m span
• ✓ 110x110mm — heavy timber framing, portal frames, significant load-bearing structures

For structures subject to significant loads (snow, wind, spans> 4m), consult a structural timber engineer or carpenter for precise sizing.

Installation advice

Never bury an untreated post directly in the ground — even class 3 Douglas fir deteriorates rapidly in contact with damp soil. For buried posts, use stainless steel fixing plates anchored in concrete, or opt for class 4 treated timber (pressure-treated). For posts set on a slab, use adjustable galvanised steel or stainless steel post bases. Apply a protective finish to all faces before installation, paying particular attention to cut ends.

Maintenance and protection

Apply a saturator or exterior wood oil to all faces before installation, paying particular attention to cut ends. Renew every 2-3 years. Douglas fir naturally turns grey without protection but retains its mechanical properties. Never bury directly — use stainless steel fixing plates.

WoodUp Tip

For a pergola with a planed Douglas fir post 90x90mm at 240cm height, anchor in adjustable stainless steel post bases rather than directly in concrete — this allows you to correct the plumb without additional masonry work. For further guidance on sizing, consult the timber framing guide.

Important before purchasing: Air drying may leave slight shrinkage cracks on large sections — this is normal and natural. These cracks do not affect the strength or durability of the post.

Frequently asked questions

Complementary products

Rough Douglas fir post — same species, natural sawn appearance

Rough Douglas fir rafter — same species, rafter format

Rough Douglas fir board — same species, board format

Douglas fir exterior saturators and oils