Holton Heath repointing: find the cause first

Nineteen eighties cavity brickwork. The busiest building period here was the 1980s, and better than a third of the housing went up between 1983 and 2008. That is all cavity work: a single outer skin of fired brick in a cement and sand mortar, struck weather or bucket handle. It pits and opens at the arris rather than washing out, water stands in the hollow, and a hard frost lifts flakes off the brick faces either side. Matching it means matching the sand, the gauge and the strength rather than only the colour, so a trial panel goes up on a discreet elevation for you to judge in daylight.

Finding the cause before pointing the strip. On brickwork this age an open joint is almost always local. A downpipe letting go at the shoe and throwing water at the same square metre of wall. A gutter running over. A drive or patio laid up above the damp proof course so the bottom courses never dry. We deal with the cause at the same time as the mortar.

Raking, filling and finishing. Joints come out to about twice their width, perpends by hand. An angle grinder is faster along a straight bed joint and it is also how a wall loses its arris, which is why it stays in the van. Joints are damped down before filling, struck to the profile the wall already carries, and brushed back once the mortar has taken up.

Blown faces. Where a face has spalled we cut the brick out whole and turn or replace it against a sample held on the wall. A mortar fill never matches and falls out inside a couple of winters. The frost damage collects above the damp proof course, under sills and beside downpipes rather than spreading evenly.

Chimneys, and the rest at low level. A stack takes weather on four sides with nothing warming it from inside, so its joints go friable well before the walls below and the penetrating damp that follows lands on a ceiling. That is work at height and wants a scaffold, priced on its own line. With better than a quarter of the homes here single storey, most walls come off a tower instead.

The older handful. A small share of property here predates 1919 and is solid wall rather than cavity, which means lime and nothing harder. We check which you have before quoting, because the two need opposite mixes.

No rate per square metre: the area tells you almost nothing until somebody has looked at what the joints are actually like.

Getting to it. A bungalow with a long weather side, a detached house with a stack on the ridge and a short strip of wall under a leaking gutter are three different set ups, and only one needs a platform at all. A chimney or a gable wants a scaffold, and how long the platform stands matters as much as how big it is. Access under the work at height rules is a priced line, not absorbed into a rate.

The joints decide it, not the wall. How deep the joints have to come back, and whether the faces have already spalled, sets the hours far more than the area does. Hand raking is slow, but a disc widens the joint and takes the arris off.

Matching is the part that shows. Too strong a mix holds water against a soft brick and the face blows off in the first hard frost. Lime is the right answer on most pre-1919 walls here.

Comparing quotes? Ask how deep the joints are raked and by hand or disc, what the mix is and whether it was matched, how many spalled bricks are being replaced, and whether the scaffold is in the price.

The bulk of the brickwork at Holton Heath dates from the 1980s onwards, and that is worth knowing because the mortar changed during the decades either side of it. Older cement mixes were usually gauged with lime as well, which left a joint that was softer than the brick and eroded gently as it aged. By the eighties the lime had largely gone, replaced by an air entraining plasticiser, and mixes were specified stronger. The result is a joint that stays hard while the brick beside it takes the punishment, so the failure shows up as pitting at the arris and spalled faces rather than as washed out joints.

Two things follow. Matching a mortar on a house this age means matching its strength as well as its sand and colour, because a mix that is too soft erodes out of a modern joint just as surely as one that is too hard wrecks an old wall. And do not let anybody tell you a house of this vintage wants lime: it does not, unless yours is one of the few here that predates 1919. Ask whoever is quoting what mix they propose and why.

We cover Holton Heath, Sandford, Lytchett Minster, Upton and across to Wareham and Poole, broadly BH16, under Dorset Council. You are dealing with Bournemouth Roofing & Building, the trading name of Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which you can look up in a minute. Thomas Hannen's business, and he is the one who comes out to price the job, not a salesman. A verified customer's 10 out of 10 on Checkatrade. The visit and the written quote are both free.