Repointing and lime mortar in Corfe Castle

Rubble walls and the wide joint. The older buildings in Corfe Castle are local Purbeck limestone laid in thin, roughly coursed beds with a good deal of mortar between and behind the stones, so a fixed raking depth is meaningless here.

On a Corfe Castle wall we take out what is loose, friable or crumbling, follow it back to sound material, and fill deep voids in stages. Hand tools only: an angle grinder on soft limestone leaves a sawn line down a wall that was never straight.

Ashlar and dressed work, which is a different job. Window and door surrounds, quoins and the better frontages in Corfe Castle use dressed stone with joints a couple of millimetres wide, and a rubble mix will not go into those. They want a fine lime putty mortar with a finer sand, worked in with a thin blade. Treating an ashlar joint like a rubble one is how a good frontage ends up coarse.

The mix. Purbeck limestone is soft and permeable and the Corfe Castle walls are solid walls with no cavity, so the wall sheds water by evaporating it back out through the joint and has to stay breathable. That means an NHL lime or lime putty mortar gauged to the original sand for colour and texture, kept back a few millimetres off the face and brushed once it has taken up, so the stone reads as the surface of the wall. A weather struck or bucket handle profile belongs on brickwork; on stone the finish is flush or recessed.

Taking cement back off. On old walls in Corfe Castle the usual repair is undoing hard sand and cement pointing applied in the last fifty years. It comes off slowly with hand tools, because the cement is stronger than the stone and will lift a face away. Where a face has spalled we cut it back or piece in a matching stone against a sample, then point the surround softer so the repair is not the hardest thing on the elevation.

Brick stacks, and the Victorian additions. Even where everything below is stone, the chimney above the roof line is often fired brick. A stack takes weather on four sides with nothing warming it, so its joints wash out first and the penetrating damp lands on a ceiling below. We repoint the stack, renew the flaunching round the pots and make good the junctions. A low stack sometimes comes off a tower; anything on a main ridge is a scaffold, priced as its own line.

Garden and boundary walls. Many of the stone walls along the Corfe Castle lanes were built with very little mortar and meant to let water through, so pointing one up solid takes that drainage away. Where a wall is shedding stones we bed and pin them back in a soft mix. Past that, we say so rather than sell you pointing that will not hold.

We never price repointing per square metre. Area says little until somebody has scraped the joints. Access. A cottage right on the village street with nowhere to stand a tower, a stone gable off a lane and a garden wall along a track are three different set ups. Lime needs days to cure, so the scaffold on a chimney or gable stays up longer, and under the work at height rules that hire time is priced along with its size.

Raking. Soft stone and old brick are raked out by hand with a plugging chisel. A grinder is faster but opens the joint wider and chips the arris. How deep we have to go, and how many faces have already spalled, sets the hours.

Mix and weather. Old walls in Corfe Castle want lime, because cement traps water in the stone and frost then blows the face off. Lime can only go on when it is neither freezing nor baking, so an autumn job may carry extra hessian and covers.

Comparing quotes? Ask how deep they rake and with what, which mortar mix they will use and whether it is matched to the old, and whether scaffolding is included.

Most villages have a handful of listed buildings. Around Corfe Castle there are 134 entries, which changes the running order of a repointing job. On a listed building the mortar is not a finish applied to the fabric, it is part of the fabric, and replacing it in a different material or profile alters the character of the building. Doing that without consent is not a paperwork slip. It is an offence, and the owner carries it.

So the specification comes first and the trowel second. An application will want the binder named, the sand identified, the gauge stated and the joint finish described, and often a sample panel built on the wall first. None of that is quick, so allow for it. It also means a quote saying only that the wall will be repointed is no use here, because it does not say the one thing the council will ask about.

If your building is not listed you are still inside the conservation area, where appearance is controlled even though the fabric is not. Either way: get the mix and the finish written down before you agree a price, so what is quoted, what is applied for and what goes on the wall are the same thing.

We are based in Boscombe, about eleven and a half miles away, and we repoint in Corfe Castle, Church Knowle, Kingston and Harmans Cross, and on to Wareham and Swanage, all under Dorset Council. Thomas Hannen owns the firm and comes out to price every repointing job in person.

The limited company is Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which is public on Companies House. A verified customer gave us 10 out of 10 on Checkatrade. The survey visit is free, as is the written quote with each line broken out. Before you book a visit in Corfe Castle, you can read our customers' Google reviews, word for word, on our reviews page.

Most repairs in Corfe Castle need no application at all. What decides whether a change to the outside of your house does is who the council is, whether a conservation area or a listing applies, and whether the place sits in a protected landscape.