When Repointing Has Failed, and What Goes Back

Mortar is supposed to be the weakest part of a wall. When the pointing is harder than the brick — which is what a cement mix on a soft London stock does — the wall stops decaying through the joint and starts decaying through the brick face instead. A joint raked out to 10mm and refilled is maintenance. A spalled brick face is not.

That single idea decides most repointing arguments, and it is why "it looks tidier" is a bad reason to repoint and "the faces are shelling" is an urgent one.

First: has it actually failed?

Three checks, none needing scaffold.

1. 01Rake a joint with a key. Run a key or a screwdriver along the mortar. Sound mortar resists. If it powders, or you can pull out more than about five millimetres by hand, the binder has gone and that elevation is a candidate.
2. 02Look at the bricks, not the joints. Crumbling arrises, or faces shelling off in flakes while the mortar stands proud of them, means the mortar is harder than the brick. The wall is eroding through the brick because the mortar will not let it erode through the joint.
3. 03Find out whether it is a crack or a joint. A straight vertical or stepped crack running through BOTH brick and mortar is movement, not pointing. Repointing it conceals the evidence and the cause continues underneath.

The one that is not a repointing job

A crack that crosses bricks as well as joints is structural. Filling it makes the wall look repaired and removes the only thing anyone could have monitored. If a crack is wider at one end, or steps diagonally, get it looked at before anyone mixes mortar — see cracks above windows and doors and, where movement is the concern, underpinning explained.

What the regulations actually give you

There is no Approved Document that says "repoint your house like this" — repointing an existing wall is usually maintenance rather than building work. But the documents do publish the figures a specification should be arguing with, and they are the numbers to hold a quote against.

Approved Documents are statutory guidance to the Building Regulations 2010 for England. Compliance is judged against the Requirements in Schedule 1; the Approved Document shows one way of meeting them. Your building control body has the final word on your specific building.

Read the fourth row against the first. The same document that specifies a lime-containing mix for a render backing names cement mortar for a damp-proof course — because a DPC's job is to stop water and a wall face's job is to let it out. Cement is not a worse material; it is a material for a different job, used in the wrong place on most of London's solid-wall stock.

Lime or cement, decided properly

The two things that make repointing fail early

Depth. A joint scraped a few millimetres deep gives new mortar nothing to key into, and it drops out inside a few winters. The working rule is at least twice the joint width, cut square rather than feathered. Approved Document C's ten-millimetre rake-out for render is the nearest published figure and a reasonable floor.

Weather and water. Mortar cured in frost or in full summer sun does not gain its strength. Joints need brushing and damping before the mortar goes in, and protecting after. This is why a cheap quote in February and a good quote in February are different jobs.

What repointing will not fix

This is where most of the money gets wasted, because the symptom that sends people looking is usually damp.

The mechanism behind the first and third is set out in damp-proof course and weep holes explained.

The south-west London angle

Solid-wall stock across Wimbledon Park, Southfields, Earlsfield and Putney is largely late Victorian and Edwardian, which means soft brick and originally lime-based joints. Much of it was repointed once in the second half of the twentieth century, in cement, because that was what everybody used. Those elevations are the ones now shelling their faces — and they are the reason the honest recommendation is often less work than expected on the joints and more on the ground levels and the rainwater goods.

What this costs, and why there is no number here

There is no price on this page, and that is deliberate. Our estimator prices eight project types and standalone repointing is not one of them — so any figure here would be typed rather than calculated, and this site's rule is that a displayed price derives from the pricing engine or it does not get displayed.

Two honest routes instead:

• Repointing inside a wider job. If the brickwork is part of a renovation or an extension, it prices as external works within that scope, and the estimator will give you a real band for the whole project.
• Repointing on its own. That needs somebody to look at the elevation, the exposure and the brick. It is a survey, not a calculator input.

Our interest, declared

We are a design-and-build contractor, and a whole-house renovation is a far larger contract than an elevation of pointing. So the incentive on this page runs towards telling you the brickwork is part of a bigger problem. Test that: ask for the three checks above to be shown to you on your own wall, and ask what the ground level is doing before you agree to any scaffold.

Before you accept a quote

1. 01Get the mix written down. Cement, lime and sand proportions, and the sand. A quote that says repointing and gives no mix is a price for an unspecified job.
2. 02Get the rake-out depth written down. At least twice the joint width, cut square. If it is not in the quote, it is not priced, and depth is the first thing to disappear on site.
3. 03Establish it is pointing and not movement. Anything crossing the bricks gets looked at before mortar is mixed. A filled crack is a monitoring record destroyed.
4. 04Check the ground level against the DPC. At least 150mm of brick between the damp-proof course and the adjoining ground. If a patio has buried it, that is the job, not the joints.
5. 05Ask what happens to the weep holes. On a cavity wall they stay open. Confirm whoever is pointing knows which they are.
6. 06Agree the weather rule. No mortar in frost or in beating sun, and joints damped before and protected after. Put it in writing so a delay is expected rather than argued about.
7. 07Ask for a test panel. One square metre, cured, looked at in daylight before the rest is priced or started. Colour and joint profile are irreversible across an elevation.

The one line to take away

Look at the brick faces, not the joints. If the faces are going and the mortar is standing proud, the last repointing was too hard — and the job now is to put something softer back, not something neater.

2VP is the builder, not a marketplace: one contract, one named project lead, and no introducer fee stacked on the build cost. On a wall where the honest answer is often "the ground level, not the pointing", it matters that the person telling you is the person who would have done the work.