Help & Advice

As a general guide, you'll need around 60 standard bricks per square metre for a single-skin wall. The exact number depends on the brick size, mortar joint thickness and the type of bond being used. Always allow an extra 5–10% for cuts and wastage.

A standard 440 x 215mm block gives you 10 blocks per square metre. As with bricks, allow 5–10% extra for cuts, especially around openings.

Facing bricks are made to be seen and come in a huge range of colours and textures. Common bricks are cheaper and used where they'll be hidden or rendered. Engineering bricks are dense and low-absorption, used below damp proof course, for manholes and anywhere strength and water resistance matter.

A 1:5 or 1:6 cement to building sand mix suits most general brickwork. Drop to 1:3 for work below damp proof course, engineering brick and exposed positions. Use a plasticiser rather than washing-up liquid, and keep the mix consistent or the colour will vary between batches.

Cement is an ingredient used to make concrete. Concrete is produced by mixing cement with sand, aggregate and water.

Building sand is used for bricklaying mortar. Sharp sand is used for screeds, block paving, concreting and laying paving slabs. Kiln-dried sand is used to fill the joints between block paving after compaction.

As a guide, one bulk bag of ballast mixed with approximately six bags of cement produces around 0.5 cubic metres of concrete, although this varies depending on the mix ratio.

Standard plasterboard is suitable for most internal walls and ceilings. Moisture-resistant boards are designed for kitchens and bathrooms, while fire-rated boards provide additional fire protection where required.

The right insulation depends on where it's being installed. Rigid PIR boards provide excellent thermal performance for walls, floors and roofs, while mineral wool is widely used for lofts, partitions and sound insulation.

The vapour control layer goes on the warm side of the insulation — the inside of the building. Get it the wrong way round and you trap moisture in the structure.

Both are structural timber grades. C16 is the most commonly used and is suitable for most domestic projects. C24 is stronger, has fewer knots and is often specified where longer spans or heavier loads are required.

CLS timber has rounded edges and is kiln-dried, making it ideal for internal stud walls and framing. Regular sawn timber has square edges and is more commonly used outdoors or where appearance isn't important.

Regularised timber has been machined to a consistent depth along its whole length. It matters on joists and rafters — sawn timber varies enough that you end up packing out to get a level ceiling or floor.

Yes. Pressure-treated timber can be used indoors, although untreated timber is usually preferred unless protection against moisture or insects is required.

Yes. Pressure treatment doesn't reach the full depth of the timber, so every cut end exposes untreated wood. Brush on an end-grain preservative before fixing, particularly on anything going into the ground.

OSB is an engineered structural board commonly used for flooring, roofing and wall sheathing. Plywood is generally stronger, more moisture-resistant and provides a smoother finish for joinery and cabinetry.

400mm centres suit most decking boards laid square. Drop to 300mm if you're laying boards diagonally, or if the manufacturer specifies it — composite boards in particular often need closer centres than timber.

One tonne of MOT Type 1 covers approximately 10 square metres at 50mm depth. If laying a driveway or patio, you'll often need a compacted depth of 100–150mm depending on the application.

Measure the total area to be paved in square metres and divide it by the area of one slab. It's always worth ordering an additional 5–10% to allow for cuts, breakages and future repairs.

10–20mm gravel is commonly used for decorative areas and paths. Larger sizes are often chosen for drainage, while smaller gravels are better suited to pathways and borders.

Around 1:80 — roughly 12mm per metre — falling away from the building. Any less and water sits on it; any more and furniture won't stand level. It must fall away from the house, never towards it.

1:40 for 100mm foul drainage and 1:60 for 150mm as a general rule. Too shallow and it won't self-cleanse; too steep and the water outruns the solids and leaves them behind.

A third of the post's above-ground height is the usual rule, so a 1.8m fence wants roughly 600mm in the ground. Concrete it in on exposed sites, and set the post on hardcore rather than sitting it in the bottom of the hole.

Yes. Compact in layers of no more than 100mm. A 200mm sub-base laid and whacked in one go looks solid and settles within a year — that's what causes the dips that appear in a driveway after the first winter.

At least 150mm above finished ground level, and it must never be bridged by render, soil or a path laid up against the wall. Bridging the DPC is one of the commonest causes of damp in a solid-looking wall.

Indoor projects generally use zinc-plated screws. Exterior projects should use corrosion-resistant screws such as galvanised or stainless steel to prevent rusting.

Brick and block take a nylon plug and screw, or a frame fixing for anything heavy. Plasterboard needs a proper cavity fixing — spring toggles or metal self-drive anchors. A plastic plug in plasterboard will pull straight out with any load on it.

Building material prices are influenced by supplier costs, demand and availability. Merchant Supplies updates prices daily, but the supplier's website always shows the most up-to-date price before you purchase.

Most deliveries come on a curtain-sider with a tail lift and pump truck, which means the driver needs firm level ground to get the pallet off. It'll usually be left kerbside — drivers won't take a pallet across grass, up a drive with a slope, or through a property. Check access before ordering, and be there to take it.

Rarely. Bricks, blocks, aggregates and cement are sold by the pack or pallet because that's how they're handled. Working out quantities properly before ordering saves far more than a part load ever would.

5–10% on most materials. Go to the top of that on anything with cuts — block paving with curves or lots of edges, or brickwork with openings. Order bricks and paving in one go where you can; a second batch rarely matches the first for colour.