Timber joists and other materials for loft conversions

June 17, 2016

Here at Champion Timber we’ve got everything you need for a loft conversion job.

We have quality timber joists and structural timbers at a range of lengths in stock. We also carry all the fittings, tools and accessories you need to get the job finished.

We’ve got branches across West London, Surrey and Kent. Our trained yard staff can help you get everything you need in one easy visit. You can also order online or by phone for free next day delivery to your site or yard. Champion Timber is the trades choice for timber joists and quality construction timber.

Joistmate Xtra timber joists and accessories

At Champion Timber we source, select and machine our timber in house. Our timber is great quality and consistent as a result. This gives you peace of mind when ordering structural timbers, such as timber joists. We can even do bespoke timber for those jobs that are a bit out of the ordinary.

Our Joistmate Xtra line of timber joists is kiln dried, pressure treated with Tanalith E and strength graded up to C24. Because we machine the timber joists ourselves we’ve got a wide range of sizes in lengths up to 6 metres.

See the full range of Joistmate Xtra timber joists

Save time and money with Champion timber joists

The quality of our products means you’ll get straight, consistent timber joists with fewer knots. The higher strength allows you to use smaller timbers for the same spans — all within the regs. With eased edges, these timber joists are easier to handle too. That makes working at height safer and reduces your time on the job.

FSC certified timber joists

All our timber is FSC certified. Many C24 graded timber joists are made of imported timber and may come from unregulated sources. Because we source and machine it ourselves, we’ve got full PEFC chain of custody certification for our timber joists. That makes our Joistmate Xtra timber joists a sustainable option for your next loft conversion project.

Joist hangers, straps and fixings

We stock hot-dip galvanised steel joist hangers in sizes to suit all our timber joists. All joist hangers are independently tested and certified by BM TRADA. We can also supply stainless steel joist hangers on request.

Find the right joist hangers for your next job

We also stock steel restraint straps, sheradised twist nails and other fixings for timber joists.

Dormer windows and other structural elements

Treated softwood

We have a wide range of treated structural timbers for purlins, knee walls and dormer shells.

Sawn firrings

We also stock treated softwood firrings in identical and folding pairs for flat roofing.


Our pressure treated battens meet the latest BS 5534 certification for roof tiling. We’ve also got a massive range of sawn and planed timber for interior battening.

Download our timber brochure for details of our range

OSB board

For wall sheathing and roofing of dormer windows our OSB board is a great value alternative to ply. Made of 70% FSC mix strands and CE/CPD compliant, we can supply 2240mm x 1220mm sheets at 11mm or 18mm thick. Exterior T&G sheets at 2400mm x 600mm x 18mm are also available.

Order OSB board online

Velux windows

For loft conversions with roof lights, we stock Velux windows in sizes from 550mm x 780mm to 1340mm x 1400mm. We also supply Velux flashings to suit different tile types.

See our full range of Velux windows and flashing

Flooring: sheet materials, insulation and soundproofing

For boarding out we have a full range of sheet materials suitable for flooring. We also supply thermal and sound insulation at different thicknesses to fit with your build.


Our range of insulation can fit all project budgets and requirements. Low profile insulation boards will suit situations where you’re installing timber joists alongside existing joists. Mineral wools provide a cheaper alternative where the cavity depth allows.


Available in 100mm and 150mm thicknesses. Our perforated rockwool rolls are easy to fit between timber joists with standard 400mm centres. Lightweight, fire resistant and CE/CPD compliant, rockwool also helps absorb sound. We also stock semi rigid rockwool slabs at 600mm widths.

See our range of insulation for loft floors

Glass fibre

Non-combustible (Class 1 Surface Spread of Flame) glass fibre has long been the insulation of choice where materials cost is a concern. We carry 100mm and 170mm thickness spacesaver rolls — both of which are rated as CE/CPD compliant.

See our range of insulation for loft floors

Celotex insulation board

Where you need high performance, low thickness insulation, Celotext insulation boards are a good option. Low U values make insulation boards around twice as effective as equivalent mineral wool options. We supply Celotex insulation boards as 2400mm x 1200mm sheets in a range of thicknesses. Lightweight and easy to cut to size, Celotex boards are rated to Class 1 for Surface Spread of Flame and CE/CPD compliant.

See our range of insulation for loft floors

Monarfloor Acoustic Deck 18

Designed for overboarding existing timber floors, Monarfloor Deck 18 is made up of an 8mm soundproofing foam bonded to 18mm moisture-resistant V313 P5 chipboard. Supplied in 2400mm x 600mm tongue and groove sheets, Monarfloor Deck 18 can reduce airborne and impact sound by 49dB.

Sheet materials for flooring

OSB board

Our OSB boards are a great value alternative to plywood and are rated for flooring use, meeting the standard for OSB/3 under BS EN 300: 2006. Made up of 3 layers of cross-oriented timber strands bonded with a waterproof resin, OSB boards are strong and consistent in quality, without voids or knots.

Available as straight edged 2440mm x 1220mm boards or TG4 half sheets.


Choose from half sheets of flooring-specific plywood with tongue and groove on all 4 edges, or hardwood throughout at 2440mm x 1220mm. Rated to EN636-2S for the T&G ply and EN636-3S for the hardwood throughout, Champion’s plywood is hardwearing and easy to work with.