Plastering in Corfe Castle

Lime plaster on stone. The older walls here are limestone rubble, thick, uneven and built without a cavity. You cannot rule a wall like that straight in one pass, so the work starts by dubbing out the hollows in successive coats of haired lime mortar, each one allowed to firm up before the next, and only then a floated backing coat and a fine finish. It is slower than gypsum and it is the reason a room here takes longer than the same room in a newer house, and it wants leaving to dry before a mist coat and any decorating.

Ceilings, laths and the beams. Between the beams you will usually find riven lath with haired lime pushed through it. Those nibs of plaster over the back of the lath are all that holds the ceiling up, and once enough of them have snapped the whole panel sags and comes down in one go rather than gradually. Where most of the keys are gone the ceiling comes down and is re-lathed. Where it is sound and only tired it can be washed off and finished again. We will tell you which, and we will talk you out of boarding over a ceiling that is still moving.

Blown plaster at skirting level is the commonest complaint in an old cottage here and it is rarely solved by plaster alone. A solid wall with no damp proof course carries moisture up and lets it evaporate off the face, and the moment somebody covers that face with cement render, gypsum or a plastic paint the water has nowhere to go and takes the finish off with it. The fix is to strip the offending material, let the wall dry, and put back something breathable.

The newer houses on the edge get ordinary work: a skim over a sound wall, a bonding, browning or hardwall backing coat where a patch has blown, board on dot and dab where there is blockwork to fix to and on stud where there is not, finished in tape and joint or a full skim, artex taken back or overboarded, and bead on every corner and reveal. A hollow sounding wall in one of those is dry lining doing its job, not a fault.

The exposed elevations face the weather coming up the gap. On stone the render should be lime, softer than what it covers, in a scratch coat, a render coat and a float, left able to breathe; sand and cement or pebbledash on the same wall traps water, freezes and pushes the face off the stone. On modern blockwork a thin coat silicone system is the right answer instead, or a monocouche where the colour is wanted through the material, with a bell cast bead at the base.

No rate per square metre. What sits behind the finish decides it: sound plaster takes a skim, a hollow wall comes off and brings a backing coat with it. A stone cottage with its door straight onto the pavement, a house on the lanes behind with a yard, and a newer place on the edge with a drive are three different jobs. Outside, render brings a tower or a full scaffold into the price, and the work at height rules are why that is its own line. A full re-render counts as renovating a thermal element, so Approved Document L and building control take an interest.

We cover Corfe Castle, Church Knowle, Kingston, Ridge and the BH20 addresses across Purbeck, with Dorset Council for planning and building control. Send the postcode if you are not sure whether we come out that far. 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.