B&Q timber stock lengths: CLS, sheet goods and a wall shelf cut list

B&Q (diy.com) is where most UK hobbyists start. Their timber range is narrower than a trade merchant, but it covers the two sections you need for most interior projects: CLS studwork at 2400 mm and 3000 mm, and standard 2440 × 1220 mm sheet goods. The tables below list what they stock with prices verified from diy.com. At the end, a worked cut list shows how to build a three-shelf wall unit from just one 3000 mm and one 2400 mm length of 38 × 89 mm CLS for around £15.60.

CLS studwork timber

CLS (Canadian Lumber Standard) is kiln-dried, planed on four faces with rounded corners. B&Q sells it under the C16 strength grade. The dimensions on the label are the finished (actual) sizes: 38 mm and 89 mm are what you will measure on the piece, not nominal sawn dimensions. It is designed for internal stud walls, partition frames and similar dry applications.

B&Q stocks CLS in two standard widths and two standard lengths. Prices below were verified from diy.com product pages.

Source: diy.com product pages for C16 CLS timber, accessed 2025–2026. Prices include VAT. Check the site for current pricing before ordering. A 3000 mm length of 38 × 63 mm may be available in store or in packs online; confirm at your local branch.

The 38 × 89 mm section is what tradespeople call "4 × 2" in old money (38 mm is close to 1.5 in, 89 mm is close to 3.5 in). The 38 × 63 mm is the "3 × 2" or smaller stud, used for non-load-bearing partitions. Both are untreated and intended for dry interior use.

B&Q does not stock the same breadth of structural sections as a trade merchant. If you need 47 × 100 mm sawn treated for joists, roof rafters or a garden room, a builders merchant such as Jewson or Travis Perkins is the better source. For a stud partition or a shelf frame, the CLS range at B&Q covers most needs.

Treated CLS (for outdoor or damp conditions)

B&Q also stocks a pressure-treated version of 38 × 89 mm CLS in 2400 mm lengths, sold at a higher price point (around £10.97 per piece at the time of writing, source: diy.com). Use this where the timber may get damp: a garden shed frame, a plyometric box for outdoor use, or a timber stud wall in a garage with no damp proof course. For a dry internal partition, the untreated C16 version is sufficient and cheaper.

Plywood sheet goods

B&Q carries hardwood plywood (a hardwood-faced sheet with a mixed core) in the standard UK full-sheet size of 2440 × 1220 mm and, for several thicknesses, a half-sheet panel at 1220 × 610 mm. The half sheet is useful for smaller projects where a full sheet would be wasteful to transport and store.

Source: diy.com hardwood plywood product pages, accessed 2025–2026. Prices include VAT. The half-sheet panel is listed at a higher per-m² rate than the full sheet but saves waste for small projects. Stock levels vary; confirm before visiting.

B&Q also stocks 12 mm and thinner hardwood plywood in the same full-sheet size, as well as structural OSB. Marine and exterior-grade plywood are stocked in some branches; check diy.com for current availability.

MDF sheet goods

Standard MDF at B&Q comes in the full-sheet 2440 × 1220 mm format at multiple thicknesses. The 18 mm sheet is the most useful for shelving, cabinet carcasses and painted furniture.

Source: diy.com MDF product page, accessed 2025–2026. Prices include VAT. Moisture-resistant MDF (green-core) is also stocked at a higher price; use this in kitchens, bathrooms or anywhere condensation is likely.

Does B&Q cut timber to size?

Most B&Q stores offer an in-store timber cutting service for a small charge per cut. The service is cross-cutting only at most branches: they will cut a length shorter, but they will not rip a board down its length. Tolerances are a few millimetres either side, so the service is good for rough sizing but not for fine joinery.

For sheet goods, B&Q stores with a panel saw will make straight cuts across or along a full sheet. This is useful for getting a sheet into a car; it is not precise enough for a kitchen cabinet build where panels need to be within 1 mm of the target size.

If you need more precise panel cutting, specialist sheet suppliers and online services (such as B&Q's own "wood cut to size" service) offer finer tolerances.

Worked example: three-shelf wall unit in 38 × 89 mm CLS

A simple wall-mounted shelf unit: 900 mm wide, three shelves at 300 mm vertical spacing, no back panel. Outside height 1000 mm. All structural parts in B&Q 38 × 89 mm C16 CLS.

How the shelf length is calculated: the unit is 900 mm wide outside edge to outside edge. Each upright is 38 mm thick (the face going left to right). The shelves sit between the uprights: 900 minus 2 × 38 = 824 mm per shelf.

Parts list

Total timber needed: 2 × 1000 + 3 × 824 = 2000 + 2472 = 4472 mm.

Cutting plan: 1 length of 3000 mm and 1 length of 2400 mm

One 3000 mm length at £8.95 and one 2400 mm length at £6.65 = £15.60 total. A 3 mm saw kerf is assumed between each cut.

Total waste: 919 mm across both lengths (17%). The 749 mm offcut from the 2400 mm length makes a useful horizontal wall cleat, a shelf stop rail, or a test piece for finish testing.

Why not two 2400 mm pieces? Two 2400 mm lengths = 4800 mm total. The parts total 4472 mm. That looks like it would fit, but the 1000 mm uprights cannot both come from a single 2400 mm piece once you allow for a shelf alongside them. Trying: 1000 + 3 + 1000 + 3 + 824 = 2830 mm, which is 430 mm longer than 2400 mm. You would need three 2400 mm pieces at £19.95 versus two lengths (3000 + 2400) at £15.60. The mixed-length approach saves £4.35.

Shelf boards

The unit above gives you the structural frame. For the actual shelf surfaces, add three boards of 18 mm hardwood plywood cut to 824 × 200 mm (or whatever depth suits your wall). One full sheet at £35.80 yields far more than three shelf boards; if you only need these pieces, ask the in-store cutting service to make the cross-cuts for you and take the remainder for future use, or choose the 1220 × 610 mm half panel at £19.50 if it is in stock.

Plan your own B&Q cut list

Once you know what B&Q stocks and at what lengths, the question becomes: how do your required parts nest onto those standard lengths with the least waste and cost? That is exactly what SawReady calculates. Enter your parts, set the stock lengths to match what B&Q carries, and it finds the most efficient combination to buy.

Plan my B&Q timber cuts