How to Tell If Your House Needs Repointing

The screwdriver test: the quickest check you can do

Pick a section of wall, ideally a south west facing elevation or anywhere below a gutter, and press the tip of a flathead screwdriver into a mortar joint using moderate hand pressure. Sound mortar will resist and you will barely mark it. If the screwdriver sinks in, or the mortar crumbles away as sand and grit, that joint has failed.

Do this in five or six places across different elevations, including low down near the damp proof course and up as high as you can safely reach. Failure is rarely uniform. It is completely normal to find one weathered gable needing attention while the front elevation is perfectly sound, and that difference matters when you are deciding scope.

• Mortar that crumbles to sand under light pressure
• Joints recessed more than about 10mm behind the brick face
• Sand or grit collecting on windowsills and at the base of the wall
• Gaps you can see daylight or a shadow line through
• Vegetation, moss or small plants rooted into the joints

What it looks like from the outside

Walk the perimeter of the house on a dry day and look along the wall at a shallow angle rather than straight on. Raking light shows up recessed and hollow joints far better than a face on view. Look for dark staining or a persistent damp patch on brickwork, particularly under sills, behind downpipes and where an extension meets the original wall.

Inside, damp patches on chimney breasts and on the inside face of exposed walls often trace back to failed pointing rather than a rising damp problem. Birmingham has a lot of solid nine inch brick walls from the Victorian and Edwardian period with no cavity, so water that gets into an open joint has a direct path to the internal plaster. On post war cavity walls the symptoms show up more slowly, which is why people often miss the early stage.

Common causes around Birmingham housing stock

The single biggest cause of premature failure locally is hard cement pointing applied over soft lime bedded brickwork. A lot of terraces and semis in areas like Moseley, Handsworth and Kings Heath were built with lime mortar, and a strong sand and cement mix repointed in the 1970s and 80s traps moisture in the brick instead of letting the joint breathe. The brick faces then spall and blow, and you end up with a bigger repair than pointing alone.

Frost is the other one. Water sits in an open joint, freezes overnight and expands, and each cycle opens the joint a little further. That is why damage accelerates over a couple of bad winters after years of looking stable. Exposed gables, parapets, chimney stacks and any brickwork above roof level weather fastest because they get wet from more directions and dry slower.

How urgent is it, and what to expect

Not every recessed joint needs immediate work. If mortar is weathered but firm and there is no internal damp, you can reasonably monitor it and plan the job. Treat it as urgent if you have visible daylight through joints, internal damp appearing, loose or moving bricks, or a chimney stack with open joints, since that becomes a safety issue as well as a water one.

Repointing is priced by the square metre and by access. As a rough guide, expect somewhere in the region of £40 to £90 per square metre for hand raked and repointed brickwork, with scaffolding on top where the work is above single storey height. Chimney stacks are usually quoted as a separate item. Anyone quoting without looking at the actual mortar, or offering to seal the wall with a waterproof coating instead of repointing it, is worth being cautious about.

Good work means raking the old joint out to roughly twice its width, around 20mm on a standard 10mm joint, using hand tools or a carefully controlled grinder rather than an angle grinder run along the brick edges. The new mortar should be matched to the existing in strength and appearance, which on older Birmingham property often means a lime based mix rather than straight cement.