Tolpuddle repointing, and the plinths under cob

Cob plinths. Several cottages here are an earth wall on a plinth of brick, flint or stone, and the plinth is the part we can work on. Failed joints let water into the bottom of a wall that has no damp proof course and never had one, and an earth wall that stays wet does not spall, it softens. We rake the plinth joints by hand, back to sound material, and point in a natural hydraulic lime kept open so the base carries on drying outwards. Cement near a cob plinth traps the water and pushes it into the earth above, the one mistake here that cannot be pointed away afterwards.

Brick and flint walling. Much of the older walling is flint with brick for the quoins, lacing courses and openings, all bedded in lime. Flint joints are deep and irregular with nothing flat to work off, so they come out with a chisel in short lengths. Brick joints are raked to about twice their width, then damped down, filled in lifts and brushed back once the mix has taken up. The profile goes back as the building carries it: flush or slightly recessed, not weather struck or bucket handle. No angle grinder on either, because a disc cutter widens the joint and takes the arris off a soft handmade brick for good.

Matching the mix to what came out. The colour of a mortar is the colour of its sand, so we take a sample of sound original from a sheltered joint and mix against it for colour and grain as well as strength. The finished joint has to sit softer than the brick or stone it goes between, so the mortar stays the sacrificial part of the wall. A trial panel goes up on a discreet elevation and is judged dry, because fresh mortar reads darker than it finishes.

Cement out of walls that were built in lime. These are solid walls and they have to stay breathable. A wall pointed hard cannot dry through its joints, so moisture leaves through the brick face and one cold night takes the surface off. You can read it from the road: pointing standing proud and crisp, crumbling brick eaten back behind it. Where the joints have washed out too, penetrating damp shows on the inside face after a wet week. Taking hard mortar off pre-1919 brickwork is slow hand work, and the repair that stops the damage.

Spalled faces and stacks. A blown face will not recover, so the brick comes out whole and a reclaimed match goes back, rather than filling the hollow with mortar. On a cottage the stack is often the only masonry standing clear of the roof, so its joints and flaunching go long before the walls do. That is work at height, and the platform is priced as its own line.

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

Getting to it. A cottage straight onto the street, a farmhouse with a yard, and a roadside wall with traffic going past are three different set ups before a joint is opened. The work at height rules are why the scaffold is a priced line rather than something 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.

Matching is the part that shows. Too strong a mix is the classic mistake, and one hard frost takes the face off soft brick. Lime is right on most pre-1919 walls here.

Comparing quotes? Ask how deep the joints are raked and by hand or by disc, what the mix is and whether it has been matched, and whether the scaffold is in the price. Two quotes for the same job are usually two different jobs.

Cob is unfired earth. It is a perfectly good wall and plenty are still standing here after two or three hundred years, but it survives on an old rule: a good hat and a good pair of boots. The hat is the roof and the overhang. The boots are the masonry plinth, usually a couple of feet of brick, flint or stone, and the mortar in that plinth is the only part of the boots you can maintain.

When those joints open, water gets into the base of a wall that has no damp proof course anywhere in it. Brick under those conditions spalls and can be cut out and replaced. Cob does not. It takes the water up, softens, loses its strength at the bottom and slumps, and at that point you are not repointing anything. So the pointing at ankle height is worth more than the pointing at eye height, and it is the part most quotes skip because nobody stands and looks at it.

Two things follow. Keep the plinth open: lime mortar, nothing dense, and no cement render run down over it, because sealing the boots moves the damp up into the earth. And keep the water off it, which means checking where the downpipes and gullies discharge and getting a raised path or flower bed back down away from the wall. We look at that on the visit and say plainly if the pointing is not the first job.

We cover Tolpuddle, Affpuddle, Briantspuddle, Puddletown, Milborne St Andrew and Bere Regis, out across DT2, with Dorset Council as the planning authority. 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.