Repairs: walls

Problem 2: Cracking in mortar joints (sand-based/other brick types)

Following the widespread use of calcium silicate and alumino-silicate-based bricks in the 1960s and 1970s, it is common to see cracks in mortar, often coupled with inadequate movement joints. Significant expansion cracking is frequently apparent.

Solution

Cutting in new expansion joints (and reinforcing the reveals with extra wall ties) is usually the only economic answer. Generally buildings that incorporate this type of brick were originally built to a budget and are unlikely to warrant an expensive cosmetic treatment.

Bungalow with stepped cracks in the gable wall

Cost sequence - cutting-in expansion joint to cavity wall out leaf

  1. Assumed wall height to 2 storeys/5 metres.
  2. Determine position for retro-fit wall tie reinforcement prior to cutting expansion joint chase within wall. Install wall ties on either side of intended expansion joint chase at double the British Standard vertical centres, i.e. nominally 225mm centres; and if using a proprietary wall tie remedial system allow for drilling through vertical centre of brick in accordance with manufacturer's instructions to tap or grout wall ties to inner then external face of wall.
  3. Allow for careful repointing in colour mortar to the face finish. When wall reinforcing ties have been installed, with grout properly cured, then expansion joint cutting may commence.
  4. Fix timber batten to wall and check for plumb along position for expansion joint.
  5. Provide adequate working access/scaffold tower or appropriate platform.
  6. Using 110-volt chasing saw set to appropriate depth (slightly in excess of combined batten depth and brick depth) follow line of batten to cut chase to wall.
  7. Relocate batten and repeat process to cut second kerf to create expansion joint of nominal width, say 15mm, or as required.
  8. Fit stainless steel expansion ties in sliding plastic sleeves grouted in epoxy-modified cement mortar at, say, 450mm nominal vertical centres and across the newly formed joint. Face-point the joint to match existing/surrounding finish. Set the ties in at the centre of the face brick depth. Install compressible fill in the expansion joint and face-up with mastic, if required.

Cutting in expansion joint to cavity wall outer leaf - COST £950.

Small works pricing

Since the original price estimating in 2008 the economic turmoil of the last few years has caused some disparities in pricing - if you are reviewing these figures in the London area they may look laughable - if you are located in Hull they might still look a bit expensive. Please treat them with caution and of course always consider obtaining more than one quote against which to test prices. Reference to the BCIS or a small works pricing book such as Spons or Laxton's will help assess costs and the hourly labour rates upon which they are based.