Planed fir rafter

Name: Planed fir rafter
Brand: Levigne
SKU: CHEVSAPRAB
Price: 9.34 EUR
Availability: InStock

4-sided planed solid fir rafter and joist, untreated, sections 55x35mm and 55x75mm, lengths 200cm and 240cm, sold individually. Smooth 4-sided finish, class 2: dry indoor use or covered outdoor use with appropriate treatment — stain or paint before exposure to moisture, as untreated fir is not weather resistant. Interior framework, flooring, light partition — section to be chosen according to span and loads to be carried. Certified timber, delivered dry.

Length (cm)

Section (cm)

Reference CHEVSAPRAB5575200

€9.34 incl. tax

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Planed Fir Joist / Rafter — Interior Framework, Sections 55x35mm and 55x75mm

This planed solid fir rafter / joist is a rectangular-section piece intended for interior frameworks, partition studs, floor supports — indoor use only. Available in two sections — 55x35mm for light structures and 55x75mm for heavier spans — and in two lengths: 200cm and 240cm. The piece is delivered sawn and untreated.

The 4-sided planed fir offers sharp edges and perfectly flat faces — well suited to applications where dimensional precision is important: partition frameworks, joinery studs, interior cladding supports. The planed dimensions (55mm) are slightly smaller than the sawn size (60mm) due to machining. The term "rafter" refers to use in roofing or inclined structures, "joist" to horizontal use as a support for decking or flooring boards — the piece itself is identical, only the use differs. Indoor use only.

Key characteristics

Characteristic	Value
Species	Solid fir
Finish	Planed — untreated
Available sections	55x35mm and 55x75mm
Available lengths	200cm and 240cm
Use class	Class 2 — dry indoor use
Treatment	Untreated — to be protected according to use
Use	Interior framework, flooring, partition — excluding roof structures
Cutting	Sold individually

Key points

✓ 2 sections — 55x35mm (light structures) and 55x75mm (heavier spans)
✓ 2 lengths — 200cm and 240cm, can be cut on site
✓ Planed solid fir — class 2 — dry indoor use
✓ Dual use joist / rafter — interior flooring, framework, partition
✓ Untreated — to be protected according to final exposure
✓ Sold individually — order the exact number required

Uses and applications

As interior floor joist: primary use. The 55x35mm section is suited to light frameworks and partition studs. The 55x75mm section is suitable for floors on joists at centres ≤ 40cm. Indoor use only — untreated fir is not suitable for decking or roof structures.

As decking joist: horizontal support on which decking boards are fixed. The 55x35mm section is suitable for light frameworks and partition studs, the 55x75mm section for floors on joists with centres ≤ 40cm. Indoor use only — not sized for roof structures. Allow a 5 to 8mm gap between joists to allow ventilation beneath the deck.

In interior framework: partition studs, counter-wall batten, interior cladding support or ground-level flooring.

Installation advice

Store pieces flat on a ventilated support, off the ground and sheltered from rain before installation — untreated fir absorbs moisture quickly. For decking, use A4 stainless steel screws or fixing clips. For roof structures, prefer bolts or galvanised nails in accordance with best practice. Outdoors, apply a fungicide-insecticide treatment before installation if the species is not naturally resistant.

Maintenance and protection

In dry indoor conditions, no treatment is required. For exposed pieces, an oil-wax or varnish is recommended. Do not expose to moisture or outdoors — untreated fir deteriorates rapidly in damp conditions.

WoodUp Advice

The planed fir joist 55x35mm is precisely dimensioned — it is suitable for drylining partition frameworks. These sections are suited to light interior structures, not roof structures or outdoor decking.

Before purchasing: The sharp edges of the planed timber can be damaged if pieces are stored incorrectly or handled roughly. Store flat on a level surface, without excessive overhang.

Frequently asked questions

Which section to choose between 55x35mm and 55x75mm?

The 55x35mm section is suitable for light structures: decking joists at centres ≤ 40cm, rafters for light coverings with span ≤ 1.5m, framework battens. The 55x75mm section is suited to longer spans, heavier loads (heavy tiles, snow) or wider centres. If in doubt about sizing, consult a carpenter or a timber structural engineer.

What is the difference between a rafter and a joist?

It is the same piece of timber — the difference is purely in the use. As a rafter, the piece is placed at an angle as support beneath a roof covering. As a joist, it is laid flat, horizontally, as a support for decking boards or flooring. The section and length are identical in both cases.

Does this fir joist need to be treated before use?

Untreated fir is a class 2 species — it is suitable for dry indoor use. For any outdoor or damp-area use, a fungicide-insecticide treatment is essential before installation. For dry indoor use (framework, flooring), no treatment is required.

Can these pieces be cut to the desired length?

Yes. Solid fir cuts cleanly with a circular saw or mitre saw. Order the length immediately above your requirement (200 or 240cm) and cut on site. Deburr the cut edges and apply a coat of protection on the cuts if used outdoors.

Which joist section for a deck with 21mm boards?

For 21mm thick boards laid on joists, the 55x35mm section with a maximum centre spacing of 40cm is the standard configuration. For 27mm boards or dense timbers (IPE, thick Douglas fir), the centres can be increased to 50cm. The 55x75mm section is recommended if the centres exceed 50cm or if you are laying thick cladding boards.