Repointing Calculator — How Much Mortar for Repointing?

For standard UK bricks (215x65mm) with 10mm joints raked to the recommended 20mm depth (twice the joint width), you need roughly 3-4 litres of mixed mortar per m² of wall, wastage included. Raking depth scales that in a straight line: rake twice as deep and you need twice the mortar. Joint width does not, and it is worth knowing why. A wider joint holds more mortar along its length, but it also makes the coursing looser, so there are fewer joints in each square metre of wall. Going from a 10mm joint to a 20mm one raises the quantity by about 75%, not 100%, and going down to 5mm cuts it to about 54%, not half. Our calculator works both effects out for your own dimensions.

For general repointing of modern brickwork, use a 1:1:6 mix (1 cement : 1 lime : 6 sand) or a 1:4 cement:sand mix with plasticiser. For older buildings (pre-1920) and conservation work, use a lime-based mortar (1:3 lime putty:sand) — cement-based mortar can damage soft historic bricks by being too hard and preventing moisture movement. See our Mortar Calculator for detailed mix quantities.

Rake out joints to a depth of at least twice the joint width, so 20mm for a typical 10mm joint and 40mm for a 20mm joint. That multiplier is SPAB best practice: "existing mortar should normally be raked out to a depth equivalent to twice the joint width (and deeper with wide joints)". SPAB give no fixed millimetre floor, and note that the two main UK sources differ here. LABC state 12mm to 19mm for standard brick joints in the same article that also recommends about twice the joint width, so their numeric range sits just below 2x for a 10mm joint. On soft or historic brickwork take the deeper figure; a thin surface skim has little to key into and fails early. The joint should be square-backed and free of loose material. Use a plugging chisel or hand mortar rake, not an angle grinder, which can damage the brick arrises and overcut the joints.

Use sharp sand (also called building sand or bricklaying sand) for repointing mortar. For a colour match with existing pointing, source sand locally or add a mortar tint. Avoid using soft sand (plasterer's sand) on its own as it produces a weaker mix. Many merchants sell pre-blended repointing sand with lime already included.

Good-quality repointing should last 50-100 years on a sheltered wall, or 25-50 years on an exposed wall. The main factors affecting longevity are mortar mix quality, correct joint preparation, weather during application, and aftercare (keeping the joints damp for 2-3 days to allow proper curing). Lime mortar is more flexible and can last longer on older buildings.

You remove all the old, weathered mortar from the joints down to a sound depth of at least twice the joint width, so 20mm for a typical 10mm joint. SPAB advise raking out to twice the joint width and deeper on wide joints, and set no fixed millimetre minimum. LABC give 12-19mm as the working range for standard brick joints, which is shallower than 2x for a 10mm joint, so the two do not fully agree and the conservation guidance is the more cautious of them. The volume of mortar you take out is the same volume you put back, which is exactly what this calculator works out: enter the wall area, joint width and raking depth and it reports the bed-joint and perp-joint volume in litres. Rake square-backed with a plugging chisel or hand mortar rake — both SPAB and LABC advise against disc cutters and angle grinders, which are hard to control and damage the brick arrises.

As a 2026 guide, UK repointing typically costs around £30-£60 per m² for cement-based mortar and £60-£90 per m² for lime mortar on period properties, with London and the South East at the upper end. Scaffolding (often £500-£1,000+) and access are charged separately, so a whole-house repoint commonly lands between £2,500 and £5,000+. These are market labour-and-material rates from UK trade-price guides (Checkatrade, MyJobQuote, WhatPrice), not a fixed standard, so always get itemised quotes for your job. This calculator does not price labour or scaffolding — it sizes the materials and gives a materials cost when you enter a price per 25kg bag.

It estimates the materials cost, not the full job price. Enter the average price you pay per 25kg bag in the optional price field and the calculator multiplies it by the number of cement and hydrated-lime bags needed (lime putty is sold by volume, so it is excluded from the bag count). It does not include labour, scaffolding, hire or waste disposal, which are usually the largest part of a repointing quote — for those, use the per-m2 ranges in the FAQ above as a sense-check against tradesperson quotes.