Advanced options
DIY pace of 2-4 m2 a day is realistic including raking out to 15-20mm (the slow bit: joints must be cut back square, not just scraped). Pre-1919 solid-wall houses almost always need LIME mortar, not cement: hard cement pointing on soft old brick traps moisture and spalls the brick faces, the classic renovation own-goal.
What The Repointing Calculator Works Out
- Dry mortar needed: wall area multiplied by a usage rate for the joint depth: about 1.2kg/m2 for a shallow rake-out, 1.5kg/m2 for the standard 15-20mm, 2kg/m2 for deep eroded joints. Repointing consumes almost no material: a 20m2 wall wants only 30-odd kilos, two bags.
- Working days: the area divided by your pace, rounded up. A realistic DIY pace is 2-4m2 a day because the job is nine-tenths preparation: every joint is cut back square to sound mortar, dusted and dampened before any mortar goes in.
- Mix: modern cavity-wall brick takes 4:1 building sand to cement with plasticiser. Pre-1919 solid walls were built in lime, soft and breathable by design, and need NHL 3.5 at about 2.5:1; the mortar must always be softer than the masonry it serves.
- Wall type (advanced): pick cement or lime to show only the relevant mix and binder quantities. Repointing an old house in hard cement traps moisture behind impermeable joints so it exits through the brick faces, and frost then spalls them off.
- Custom usage and wastage (advanced): override the kg/m2 figure (wide stone joints can run to 4kg/m2) and add a wastage allowance for mortar that goes off in the bucket, which on a hot day can be 10% to 20%.
- Bag size and material cost (advanced): ready-mix mortar comes in 20kg bags (typically GBP 6 to GBP 12); sand, cement and NHL in 25kg (NHL 3.5 about GBP 15 to GBP 22). The cost card shows the total and a cost per square metre.
- Total hours (advanced): days x the hours you can work, split roughly 65% raking and 35% filling and finishing, plus the number of weekends it will swallow. A grinder with a mortar-raking disc halves the raking time but risks the brick arrises; the plugging chisel is the heritage-safe tool.
- Contractor estimate (advanced): the same wall at a professional pace (around 8m2 a day) and your day rate, labour only. UK pointers charge roughly GBP 200 to GBP 350 a day, before scaffold or tower hire, which is why quotes run to thousands for a job that uses two bags of mortar.
- Joint length (advanced): about 20 linear metres of joint per square metre of standard 215 x 65mm brickwork in stretcher bond, a sobering number for planning the raking.
- Mix breakdown table (advanced): sand and binder weights for the cement and lime systems with the 25kg binder bags each needs, alongside the ready-mix alternative. Work top-down so wash-off lands on unfinished wall, and fix the leaking gutter or bridged damp course that eroded the joints in the first place.