How to Check Brickwork Quality: A Homeowner's Guide

External wall defects are the single biggest category of building defects in UK construction. LABC Warranty data puts them at 31% of all recorded defects - nearly double the next category. That's brickwork, wall ties, cavity insulation, and moisture protection all lumped together, and all things you can check yourself with nothing more than a tape measure and a pair of eyes.

This guide walks you through what good brickwork looks like, what bad brickwork looks like, and exactly what to check before the scaffolding comes down and your chance to spot problems disappears behind a coat of render or a garden fence.

TL;DR Checklist

• Mortar joints are a consistent 10mm thickness with fully filled bed joints
• Wall ties embedded 50mm per leaf, spaced 900mm horizontal / 450mm vertical
• Cavity insulation is continuous - no gaps, compression, or mortar bridges
• Weep holes present above every lintel and at the base of the cavity
• DPC sits at least 150mm above finished ground level
• No heavy efflorescence (white salt deposits) on the face
• Perpends (vertical joints) are plumb and evenly spaced
• Bond pattern is consistent stretcher bond (or whatever was specified)

The Full Guide

Mortar joints

Start with the basics. Stand back about two metres and look at the wall face. The mortar joints - both horizontal (bed joints) and vertical (perpends) - should look even and consistent. Grab a tape measure: the standard joint thickness is 10mm. A millimetre either way is fine. Anything significantly thicker or thinner suggests the bricks are being laid without gauging, and it'll look worse the more wall you build.

Now look more closely. Bed joints should be fully filled - no voids or gaps running along the course. Press your fingernail gently into a fresh joint: it should feel firm but slightly give. The joint profile matters too. Bucket handle (concave) joints are the most weather-resistant. Flush or recessed joints are acceptable but less forgiving in exposed locations. Raked joints (where the mortar is scraped back from the face) look smart but are not recommended on external walls in the UK - they collect water.

Wall ties

Wall ties are the hidden heroes of cavity wall construction. They hold the inner and outer leaves together while allowing the cavity to function as a moisture break. You can't see them once the wall is up, so check while it's being built.

Each tie should be embedded at least 50mm into each leaf of brickwork. That's 50mm into the outer skin and 50mm into the inner skin - separately. The standard spacing is 900mm horizontally and 450mm vertically, with additional ties around openings (within 225mm of the reveal, at 300mm vertical centres).

Here's the critical detail most homeowners miss: wall ties should slope slightly downward toward the outer leaf. This means any water that runs along the tie drips off on the outside, not the inside. If a tie slopes inward, it becomes a moisture bridge carrying rainwater straight to your inner wall. This is one of the most common causes of persistent damp patches that builders struggle to diagnose after the fact.

Cavity insulation

Full-fill or partial-fill cavity insulation needs to be continuous - no gaps and no compression. Insulation that's been squeezed into too narrow a cavity loses its thermal performance. Insulation that has gaps lets cold air circulate behind the inner leaf, creating cold spots and condensation risk.

Watch for mortar droppings on top of the insulation. Mortar that falls into the cavity during bricklaying can bridge the cavity, creating both a moisture path and a thermal bridge. Good bricklayers use a cavity batten - a strip of wood that sits on the wall ties and catches mortar droppings as each course is laid. If your bricklayer isn't using one, the cavity is probably full of mortar snots.

Weep holes

Weep holes are small gaps left in the mortar joint at specific points in the wall. They allow any moisture that enters the cavity to drain out at the bottom. You need them in two places: above every lintel (the steel or concrete beam above windows and doors) and at the base of the cavity wall.

Check every window and door opening. There should be at least two weep holes in the course of bricks directly above the lintel - one at each end. At the base of the wall, weep holes should be at regular intervals (typically every fourth perpend, roughly 900mm apart).

If you can't see any weep holes, ask your builder. Sometimes they're formed with plastic inserts rather than open joints, which is fine - but they should still be visible. Missing weep holes mean trapped moisture, and trapped moisture means damp, mould, and eventually structural damage to wall ties.

DPC height

See that black strip running along the top of the concrete? That's your DPC - the damp proof course. It's a physical barrier that stops moisture rising up through the masonry from the ground. Grab a tape measure. It needs to be at least 150mm above the finished ground level outside.

This measurement is to the finished ground level - not the current level during construction. If your landscaping plans include raising the ground with topsoil, paving, or a patio, the DPC still needs to be 150mm above that final level. This catches a lot of people out. The bricklayer finishes, the landscaper comes in six months later, builds a raised bed against the wall, and suddenly the DPC is 50mm below soil level. Moisture bypasses it, and damp appears inside the house a year or two later.

Efflorescence

White powdery deposits on the face of new brickwork are called efflorescence. Soluble salts naturally present in bricks, mortar, or sand dissolve in construction moisture and migrate to the surface as the wall dries out. When the water evaporates, the salts crystallise as a white residue.

Light efflorescence on new brickwork is normal and usually disappears within the first year as the wall fully dries. It can be brushed off with a stiff dry brush. Don't use water - that just re-dissolves the salts and pushes them back in.

Heavy or persistent efflorescence is different. It suggests an ongoing moisture source - a missing DPC, a leaking cavity tray, or a detail where water is getting into the wall continuously. If the white deposits keep coming back after brushing, investigate the moisture source rather than just cleaning the surface.

Perpends and bond pattern

Perpends are the vertical mortar joints between bricks. They should line up vertically every other course (in stretcher bond, which is the standard pattern for cavity walls). Stand at the end of the wall and sight along it - the perpends should form a clear, regular pattern.

Perpends that wander or don't align properly indicate either poor setting out or inconsistent brick sizes being used without adjustment. Neither is a sign of careful workmanship.

The bond pattern itself - the arrangement of bricks - should be whatever was specified in the design. Stretcher bond is by far the most common for modern cavity walls. If a different bond was specified (Flemish, English, or a decorative pattern), check it's been followed consistently, especially around openings and corners where mistakes are most visible.

Common Problems

Stepped cracking along mortar joints. This usually indicates differential settlement - one part of the building moving relative to another. Hairline cracks in the first few months might be normal shrinkage, but cracks you can fit a coin into, or cracks that keep growing, need investigation by a structural engineer. Don't accept "it'll settle" without a proper assessment.

Mortar droppings bridging the cavity. Once the wall is finished, you can't see them, but the symptoms show up as damp patches on internal walls, particularly below window openings where cavity trays have been blocked by fallen mortar. Prevention during construction (cavity battens, careful bricklaying) is far easier than retrospective repair.

Efflorescence that won't stop. Persistent white deposits mean persistent moisture. Check the DPC height, cavity trays above openings, and any render or cladding details that might be directing water into the wall rather than away from it.

Inconsistent mortar colour. This is usually cosmetic rather than structural, but it indicates that mortar batches were mixed inconsistently - different sand sources, different cement ratios, or different water content. If appearance matters to you (and on a front elevation it usually does), raise it early. Re-pointing a wall is expensive and rarely looks as good as getting it right first time.

If you're finding quality problems alongside an expensive quote, check our guide on signs of overcharging - poor workmanship paired with high prices is a particularly bad combination.

Questions to Ask Your Builder

• "Can I see the wall ties before the next courses go on?" - Any good bricklayer won't mind showing you. It takes 30 seconds and shows they're confident in the work.
• "Are you using cavity battens to keep mortar out of the cavity?" - If the answer is no, ask how they're preventing mortar bridges. There should be a method.
• "What mortar mix are you using, and is it what the structural engineer specified?" - The mix ratio affects both strength and weather resistance. It should match the specification.
• "Where are the weep holes going above this lintel?" - This checks both knowledge and intention. If the response is vague, it's a concern.
• "Can you show me the DPC and confirm the finished ground level relative to it?" - Links the current construction to the finished design. Shows you understand the requirement.