How Long Should Repointing Last in London?

The realistic lifespan

Well-executed repointing with the right mortar should last 25 to 50 years on a typical London house, and sheltered elevations can go longer. The original lime mortar on many Victorian and Edwardian terraces in Balham, Tooting and Islington is well over 100 years old and still doing its job in places.

Exposed spots wear much faster. Chimney stacks, parapet walls, garden walls and elevations facing south-west into the prevailing rain can need attention after 15 to 25 years even when the work was done properly. A rear wall under a leaking gutter can fail in under ten.

Why the mortar matters so much in London

Most older London homes are built from soft yellow London stock or red clay bricks laid in lime mortar. Lime is softer and more breathable than the bricks, so moisture escapes through the joints and the mortar wears away slowly in place of the brick.

Hard cement mortar reverses that. It traps moisture in the brick, and freeze and thaw cycles then blow the faces off the bricks around the joint, known as spalling. We regularly see 1970s and 1980s cement repointing on London terraces where the mortar looks fine but the bricks either side are crumbling. Repairing that means replacing bricks as well as repointing, which is far more expensive.

For pre-1919 houses a lime mortar, usually NHL 3.5 or a hot or putty lime mix matched to the original colour, will almost always last better and protect the bricks. Modern cavity-wall homes built with harder bricks can take a weaker cement and lime mix.

What causes repointing to fail early

When repointing fails in under ten years, it is nearly always down to workmanship or the wrong materials rather than the weather alone. The common culprits are:

• Shallow raking out: joints should be cleared to around 2 to 2.5 times their height, typically 15 to 25mm, so the new mortar has something to grip
• Feathered or smeared joints that spread thin mortar over the brick face and crack off within a couple of winters
• Cement mortar on soft, old bricks, as described above
• Working in frost or hot sun without protecting the fresh mortar, so it cures too fast or freezes
• Not dampening the joints first, which lets dry bricks suck the water out of the mix
• Leaving the cause of the damp unfixed, such as a leaking downpipe, blocked gutter or failed flashing

Signs your joints need attention

You do not need to repoint a whole house because a few joints look tired. Localised repairs are often enough. It is worth getting a closer look if you notice:

• Mortar recessed more than about 5mm behind the brick face
• Sand or grit falling out when you run a key along a joint
• Damp patches inside that line up with an external wall
• Plants or moss growing out of the joints
• Cracked or spalled bricks around hard, grey cement joints

Cost and planning in London

Costs depend on access, joint width, mortar type and how much raking out is needed. As a rough guide, London repointing often falls somewhere between £50 and £100 per square metre, with lime work at the higher end because it is slower. A typical terraced house front can come to several thousand pounds once scaffolding is included, and scaffolding alone on a London street can run from around £800 to £2,000 depending on height and whether a council licence is needed for the pavement.

Like-for-like repointing does not usually need planning permission. If your home is in a conservation area, which covers large parts of Wandsworth, Lambeth, Camden and Islington, it is sensible to check with your council, as a change in mortar colour or joint style can matter. Listed buildings need consent. Since the scaffolding is often the biggest single cost, it pays to combine repointing with chimney, gutter or roof work while it is up.