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Rough-sawn Douglas post
Rough-sawn untreated solid Douglas fir post — sections 100x100mm, 120x120mm and 150x150mm. Lengths 200cm and 240cm. Class 3. Timber framing, pergola, shed. Air-dried. Sold individually. Exterior off-ground use.
Rough-Sawn Douglas Post – Sections 100x100mm to 150x150mm, Lengths 200cm and 240cm
This solid rough-sawn Douglas fir post is a square-section piece designed for load-bearing structures: pergola, carport, garden shed, fencing, raised terrace. Available in 3 sections — 100x100mm, 120x120mm, 150x150mm — and in two lengths: 200cm and 240cm. The piece is supplied untreated, ready to be protected according to its use and exposure.
Rough-sawn Douglas fir retains its natural sawn appearance — slightly irregular texture, golden-orange hue, characteristic grain. Large sections (100mm and above) are suited to significant load-bearing structures: traditional timber framing, portal frames, agricultural sheds. Air-drying preserves the natural mechanical properties of the wood.
Main characteristics
| Characteristic | Value |
|---|---|
| Species | Solid Douglas fir |
| Finish | Rough sawn — untreated |
| Available sections | 100x100mm, 120x120mm, 150x150mm |
| Available lengths | 200cm and 240cm |
| Use class | Class 3 — natural resistance, exterior use away from direct ground contact |
| Treatment | Untreated — to be protected according to exposure |
| Drying | Air-drying — natural method |
| Conversion | Sold individually |
Key points
- ✓ 3 sections available — 100x100mm, 120x120mm, 150x150mm
- ✓ 2 lengths — 200cm and 240cm, can be cut on site
- ✓ Solid rough-sawn Douglas fir — class 3 — natural resistance, exterior use away from 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:
- ✓ 100x100mm — small lightweight structures, single-pitch carports, fencing
- ✓ 120x120mm — standard pergola, garden shed, terrace up to 3m span
- ✓ 150x150mm — heavy timber framing, portal frames, significant 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 advice
Never bury an untreated post directly — even class 3 douglas fir deteriorates rapidly in contact with moist ground. For buried posts, use stainless steel fixing plates anchored in concrete, or opt for class 4 pressure-treated timber (autoclave). For posts set on a slab, use adjustable galvanised or stainless steel post bases. Apply protection to all faces before installation, paying particular attention to cut ends.
Maintenance and protection
Exterior wood saturator or oil before installation, renewed every 2–3 years. For large sections, shrinkage cracks may be more pronounced — they do not affect strength. Never bury without a plate or class 4 treatment.
WoodUp Advice
For large sections (120x120 and 150x150mm), always pre-drill before screwing to avoid splitting. Use countersunk stainless steel screws of a diameter suited to the section. For further guidance on sizing, consult the timber framing guide.
Good to know before buying: A rough-sawn Douglas post stored outdoors can grey quickly before installation. Store it under cover or apply a protective oil coat upon receipt if installation is delayed.
Frequently asked questions
What section of post should I use for a pergola?
For a standard residential pergola (3–4m span, light roof), the 120x120mm section is generally sufficient for a height of 240cm. For a pergola with a green or heavy roof, or spans> 4m, choose a larger section. If in doubt, consult a carpenter or timber engineering office.
Can this post be buried directly?
No. An untreated post must not be placed in direct contact with moist ground — even class 3 douglas fir deteriorates in ground contact (class 4 required). Use a fixing plate anchored in concrete, or order a class 4 pressure-treated timber for buried posts.
Does this post need to be treated before use?
Untreated Douglas fir naturally resists outdoor conditions away from ground contact (class 3). To slow greying, apply an exterior wood saturator or oil before installation. Renew every 2–3 years.
What is the difference between a rough-sawn post and a planed post?
The rough-sawn post retains its 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 option provides a more refined finish. For hidden or embedded structures, the rough-sawn is equivalent.
Can these posts be painted or stained?
Yes. Lightly sand the faces (grit 80–120) before application. For exterior paint, apply a primer specifically designed for resinous wood. For stain or oil, apply directly to dry wood. Planed posts offer better adhesion for finishing products.
Complementary products
Planed Douglas post — same species, smooth surface
Rough-sawn Douglas rafter — same species, rafter format
Douglas timber framing by the m³ — large quantities available on quotation
- Species/material
- Douglas
- Use class
- Class 3 - Above ground contact outdoors
- Delivery label
- Framework
POTDOUBRU1010200
1000 Items
3420610005122
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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.
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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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