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Planed Douglas fir post
Untreated planed solid Douglas post, sections 70x70mm, 90x90mm, 110x110mm and 140x140mm, lengths 200cm and 240cm, sold individually. Air dried, class 3: natural durability outdoors with no direct ground contact — apply oil, saturator, or stain after installation to limit greying and extend service life. Pergola, carport, garden shed, load-bearing structure — planed Douglas timber post ready to assemble according to the project layout.
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 shed, fence, raised decking. 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.
Planed douglas fir 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 exterior structures: pergola, carport, raised decking.
Main characteristics
| Characteristic | Value |
|---|---|
| Species | Solid douglas fir |
| Finish | Planed – untreated |
| Available sections | 70x70mm, 90x90mm, 110x110mm, 140x140mm |
| Available lengths | 200cm and 240cm |
| Use class | Class 3 – natural durability, exterior above direct ground contact |
| Treatment | Untreated – to be protected according to exposure |
| Drying | Air drying – natural method |
| Cut | Sold individually |
Key points
- ✓ 4 sections available – 70x70mm, 90x90mm, 110x110mm, 140x140mm
- ✓ 2 lengths – 200cm and 240cm, can be cut on site
- ✓ Planed solid douglas fir – class 3 – natural durability, exterior above direct ground contact
- ✓ Air dried – natural method preserving the characteristics of the wood
- ✓ Untreated – to be protected according to use and exposure
- ✓ Sold individually
Which section to choose:
The choice of section depends on the post height, the load to be supported, and the spacing between posts:
- ✓ 70x70mm – small lightweight structures, lean-to carports, fences
- ✓ 90x90mm – standard pergola, garden shed, decking up to 3m span
- ✓ 110x110mm – heavy timber framing, portal frames, major load-bearing structures
For structures subject to significant loads (snow, wind, spans> 4m), consult a timber engineering office or a carpenter for precise sizing.
Installation tips
Never bury an untreated post directly in the ground – even class 3 douglas fir degrades rapidly in contact with moist soil. For buried posts, use stainless steel fixing plates anchored in concrete, or opt for class 4 pressure-treated timber. For posts set on a slab, use adjustable galvanised steel or stainless steel shoes. Apply protection to all faces before installation, paying particular attention to cut ends.
Maintenance and protection
Apply a saturator or exterior wood oil before installation on all faces, paying particular attention to cut ends. Renew every 2–3 years. Douglas fir will grey naturally 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 90x90mm post at 240cm height, anchor in adjustable stainless steel shoes rather than directly in concrete – this allows you to correct plumb without any masonry rework. For further guidance on sizing, consult the timber framing guide.
What to know before buying: 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
What section of post should be used for a pergola?
For a standard residential pergola (3–4m span, lightweight roof), the 90x90mm section is generally sufficient for a height of 240cm. For a pergola with a green or loaded roof, or spans> 4m, choose a larger section. If in doubt, consult a carpenter or structural engineer.
Can this post be buried directly in the ground?
No. An untreated post must not come into direct contact with moist soil – even class 3 douglas fir degrades in ground contact (class 4 required). Use a fixing plate anchored in concrete, or order class 4 pressure-treated timber for buried posts.
Should this post be treated before use?
Untreated douglas fir is naturally resistant outdoors above ground contact (class 3). To slow greying, apply a saturator or exterior wood oil before installation. Renew every 2–3 years.
What is the difference between a sawn post and a planed post?
The sawn post retains the natural sawn appearance with slightly irregular faces and nominal dimensions (e.g. 100x100mm). The planed post is machined on all 4 faces to achieve smooth surfaces and precise dimensions, slightly smaller than nominal. For exposed structures, the planed post gives a neater finish. For concealed or built-in structures, sawn is equivalent.
Can these posts be painted or stained?
Yes. Lightly sand the faces (80–120 grit) before application. For exterior paint, apply a primer specially formulated for resinous wood. For stain or oil, apply directly to dry wood. Planed posts offer better adhesion for finishing products.
Complementary products
Sawn douglas fir post – same species, natural sawn appearance
Sawn douglas fir rafter – same species, rafter format
- Species/material
- Douglas
- Use class
- Class 3 - Above ground contact outdoors
- Delivery label
- Framework
POTDOURAB99200
993 Products
3420610005290
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Dispatch within 10 days
Dispatch within 10 days when the product is in stock *.
* Except bespoke products
Dispatched within 6-8 weeks
Dispatched within 6-8 weeks for personalised and made-to-measure products.
Secure payment
Payment in 1 or 3 instalments at no extra cost. Bank transfer, cheque or PayPal
Satisfied or refunded
Satisfied or refunded if returned within 14 calendar days (Sundays and public holidays included) following delivery.
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