91±¬ÁÏ

Sand goes into more of a build than most people notice. It’s in the concrete under the slab, the mortar between the bricks, the screed under the floor, the bedding under the block paving and the trench around the cable. Order the wrong grade and the job either fails or gets done twice.

91±¬ÁÏ has supplied sand and aggregates from Darlington for over 20 years serving the North East, and this guide is the one we’d hand to a customer who rang unsure what to order. It covers the five sands most used on site, what each is for, where each is the wrong choice, and how to check a load. It’s written for groundworkers, builders, civils contractors and site managers, and the same rules apply to a homeowner ordering a bulk bag for a patio. If you already know what you need, go straight to our sand supply page.

What construction sand is

Construction sand is the fine end of the aggregate range. In UK practice, fine aggregate is material that passes a 4 mm sieve, so sand covers everything from a coarse 4 mm grit down to particles you’d struggle to see. Gravel and crushed stone sit above that line.

Sand is sold washed or unwashed. Washed sand has had the silt and clay rinsed out and suits concrete and mortar. Unwashed, or as-dug, sand keeps its fines, costs less and suits bulk fill. For the wider family of gravels, crushed stone and recycled material, see our guide to aggregate types and grades.

Types of sand used in construction

The trade name of a sand usually tells you its grain size, its grain shape and how clean it is. Sharp sand is coarse and angular, for concrete and bedding. Building sand is fine and rounded, for mortar. Fill sand is unwashed bulk material for backfill. Cable sand is screened fine sand for protecting buried services. Industrial sand is high-purity silica for specialist uses.

Sharp sand

Sharp sand is a coarse, washed sand with angular grains. It’s also called grit sand or concreting sand, and it’s typically graded 0/4 mm, meaning the grains run from dust up to 4 mm. The angular grains lock together under load.

Use sharp sand for mixing concrete, for floor screeds, for the laying course under block paving and flags, and for the base coat of render where a coarser mix is specified. It also suits lawn top-dressing and drainage in heavy soil.

Don’t use it for bricklaying mortar. The coarse grains make the mortar harsh to work and the joints won’t finish cleanly, which is the job building sand does. If you’re bedding block paving, order sharp sand.

Building sand

Building sand, also called soft sand or bricklayers’ sand, is a fine sand with rounded grains. The rounded grains give a mortar that’s smooth, plastic and easy to spread, and they let the trowel leave a clean joint.

Use it for bricklaying and blockwork mortar, for pointing, and for render top coats. It’s the sand for anything worked by hand and finished neatly.

Don’t use building sand in concrete or under paving. Rounded grains don’t lock together, so a paving bed made from soft sand will settle, and concrete made with it will be weaker than the mix design assumes. Colour varies by pit, from yellow to red, which matters when pointing has to match existing work or when a job runs across several deliveries. Ask for a sample, and order enough from one source to finish the visible work.

Fill sand

Fill sand is a general-purpose sand sold for bulk, where the job is to occupy space rather than to bond or carry a finished load. It’s usually as-dug or lightly graded, so it may contain some silt, clay or small stone.

Use it for backfilling trenches and excavations, for levelling and raising ground before a sub-base goes down, as a sub-base layer under slabs and driveways where the spec allows a sand blinding, and for filling sandbags. It’s the cheapest sand on this list and the right choice when the sand will be buried and compacted.

Don’t use fill sand in mortar or concrete. The fines and any clay content weaken a mix and hold water, and if the spec calls for a washed sand, fill sand won’t meet it.

Cable sand

Cable sand is a fine, screened sand used to bed and surround underground cables, ducts and water pipes. Screening removes the stones and sharp particles that would otherwise press into a cable sheath or pipe wall when the trench is backfilled and compacted. Its grain is finer and more uniform than sharp sand.

Use it wherever a utility spec calls for a sand bed and surround, laid below and above the service before the marker tape and main backfill go in. The utility’s specification sets the bed and surround depth, and utility companies and local authorities often name the grade they accept, so check the spec before ordering. Where a thermal specification such as ENA TS 97-1 applies to buried power cables, confirm the grade before you order. If you’re opening a long trench and need an excavator with an operator, our plant hire team works alongside sand deliveries.

Cable sand isn’t a structural material. It’s no substitute for concrete, it isn’t a paving bed and it shouldn’t go in a mix. Its job is protection.

Industrial and silica sand

Industrial sand is a high-silica sand processed to a tight grading and a consistent chemistry. On a construction site it turns up in water filtration beds, as a blasting medium and in specialist mortars and grouts where a spec names silica content. Off site, the same material feeds glassmaking and foundry moulds.

It’s rarely the right choice for general construction, because the processing that a glassworks pays for adds nothing to a concrete mix. Order it when a specification names silica content or a specific grading; otherwise sharp sand does the structural job for less.

Pros and cons of sand in construction

Sand is on every site for four reasons. It’s available almost everywhere, so supply is rarely the constraint. It costs less than cement, crushed stone or anything manufactured. It’s workable, whether shovelled, barrowed, pumped or tipped from a lorry into a hopper. And it drains well, so a sand layer under paving or against a wall moves water away from where it does harm.

Its weaknesses come from the same properties. Loose sand has no strength of its own, so it shifts under wind, water and traffic until it’s confined or bound with cement, and an unrestrained bed migrates from under the paving it supports. It’s sensitive to moisture: a wet stockpile throws off the water-cement ratio, and a dry, exposed pile blows away. Unwashed sand can carry clay, silt or salt that weakens a mix, and a clean pile picks up mud if it’s stored badly.

The practical rule is that sand is a good material inside something and a poor one on its own. Bind it, confine it or bury it, and it performs.

How to choose the right sand

Start with the job, because the job sets everything else.

Job	Sand	Why
Concrete, floor screed	Sharp sand	Angular 0/4 mm grains lock together and give strength
Block paving and flag bedding	Sharp sand	Stays put under load and drains
Bricklaying, blockwork, pointing	Building sand	Fine rounded grains give a workable mortar and a clean joint
Render top coat	Building sand	Smooth finish; use sharp sand for a coarse base coat if specified
Trench bed and surround for cables and pipes	Cable sand	Screened, stone-free, protects the service
Backfill, levelling, sandbags	Fill sand	Cheapest option where the sand is buried and compacted

Then check grain size and shape against the spec. Sharp sand for concrete is usually 0/4 mm and a mortar sand is finer, often 0/2 mm. Where a specification names a grading, order to it and ask for the grading sheet.

Colour matters only where the sand shows. Match pointing or render to existing work with a sample, and if a visible job takes several loads, ask for them from the same source. For anything buried or bound in concrete, colour is irrelevant.

Source tells you about cleanliness. Washed sand suits concrete and mortar; as-dug sand suits fill. Marine sand can carry salt and needs washing before it goes near reinforced concrete, so ask about origin if you’re unsure.

Cost comes last. The price gap between grades is small next to the cost of lifting a failed paving bed or raking out crumbling mortar.

Sand grading and testing

Grading is the spread of particle sizes in a sand. It’s measured by sieve analysis: a dried sample passes through a stack of sieves and the weight held on each one is recorded. The result is a grading sheet showing the percentage passing each sieve, which tells you whether a “sharp sand” is a true 0/4 mm or something finer sold under the same name. UK sands for concrete are graded to BS EN 12620 and sands for mortar to BS EN 13139, and each standard sets limits on how much material may pass each sieve. All materials we supply conform to current European and UK standards where appropriate, and you can ask for a grading sheet with your order.

On site, two simpler checks cover most jobs. A silt test needs a jar, a handful of sand, water and a few hours of settling; if the silt layer that forms on top is more than about a tenth of the sand depth, the sand is too dirty for concrete or mortar. A squeeze in the hand tells you how much water the sand is holding, which changes how much water goes into the mix.

For a domestic patio, a clean stockpile and the silt test are usually enough.

Alternatives to sand

For some jobs another aggregate does the work better. Crushed rock fines, sometimes sold as grit or crusher dust, are used in place of sharp sand under paving where a spec allows, and they lock together at least as well; we produce crushed rock fines from our crushing service as part of the screening process. Manufactured sand, made by crushing rock to a sand grading, goes into concrete where natural sand is scarce or specified, and its angular grains behave much like sharp sand. Recycled aggregate, meaning crushed concrete, crushed brick and road planings, replaces fill sand for bulk fill and sub-bases and is often cheaper. None of these replaces building sand in mortar or render, because nothing else leaves a clean finish under the trowel.

How we supply sand

91±¬ÁÏ & Screening stocks sharp sand, fill sand and cable sand, supplied as loose loads and bags. Other grades can be sourced on request if your project needs something specific. Collect from our County Durham depot, or have it delivered across the North East, with wider delivery by arrangement.

Prices depend on grade, quantity and delivery distance, so there’s no rate card on this page. Call 01325 808760 or get a quote with your postcode and tonnage. Trade and commercial orders come first, and bulk domestic orders are welcome.