Wall insulation in Corfe Castle

Working out the wall comes first. Wall thickness is measured at a reveal, the bond looked at, and where a house has a later extension or a rear wing we drill one hole and borescope it, because plenty of cottages in Corfe Castle are stone at the front and brick and block at the back. Two halves of one house can want opposite treatments.

Internal wall insulation, done thinly. On Purbeck stone the lining has to let moisture pass, so it is wood fibre board, on battens or bedded flat, finished in lime plaster. On a rubble wall the batten route wins because the background is not flat. PIR board or insulated plasterboard belongs on the brick and block wings, not the stone. In a cottage the constraint is space, so it often makes sense to use less thickness than a specification sheet would and accept a poorer U value rather than lose 100mm from a tight room.

Where thickness cannot be given up. In a Corfe Castle cottage, around a staircase, in a hall or on a reveal with an old frame close to the face, an aerogel backed board gets a useful improvement into 20 or 30mm. It costs more per square metre and it is the right call in exactly those places, not across a whole elevation.

The junctions, which is where it goes wrong. Reveals returned, the lining carried past the floor junction, joist ends considered before anything is sealed, and the party wall thought about in a terrace. A wall that simply stops leaves a cold bridge at every edge, and black mould turns up on the edge rather than the middle. The vapour control layer is taped continuously, and on old masonry we prefer a breathable build up so the wall dries inwards rather than holding moisture at the dew point.

Cavity fill on the newer housing. The post war houses in Corfe Castle do have a cavity. Clear and dry, it takes bonded bead or blown mineral wool in a day, cuts the heat loss through that wall sharply and the payback is short. Slumped or failed fill is extracted through drilled holes and either replaced or left out. A fill is normally covered by an independent scheme run separately from the installer.

What we would talk you out of. External wall insulation on a stone elevation in Corfe Castle: the boards and render carrier bury the stone and the application will fail. Injected damp courses sold as a cure for condensation. And lining a wall that is wet from a blocked gutter or a cracking cement render, because that boards over a fault rather than fixing it, and a failed render behind a lining is a wet cavity you cannot see.

Ventilation, and draughts. Extract in the kitchen and bathroom, trickle vents in the windows, air bricks kept clear. Approved Document F sets what the ventilation has to do, and tightening a house without it is how mould starts.

We don't work to a rate per square metre. The open middle of a wall is quick; every window, door and floor edge is slow.

What the wall is. An empty, dry cavity is injected from outside in a day. Solid stone has no cavity, so it is lined inside or insulated outside, a different job at a different price. On stone the lining must let moisture pass, for example wood fibre board finished in lime plaster, because a foil-faced board on a wall that takes driving rain can trap water behind it.

Getting to it. A stone cottage in a terrace on East Street, a detached house off the Wareham road and a post-war bungalow each need a different survey and different kit. Injecting a cavity is done from outside, off a tower or scaffold under the work at height rules. Lining is done from inside, room after room.

The edges. Heat leaks, and condensation forms, around window and door reveals, where the floor meets the wall, at the eaves and along any party wall. Getting those details right takes longer than lining the flat of the wall, and a cheap quote is usually cheap because it skips them.

Ask a competing installer whether they actually looked inside the wall with a borescope, what system and thickness they propose, how they will treat the reveals and ventilation, and who replasters afterwards.

We cover Corfe Castle, Church Knowle, Kingston, Stoborough and the BH20 addresses around them, all under Dorset Council, and it is a drive of about eleven and a half miles from Boscombe to reach them.

Thomas Hannen owns Bournemouth Roofing & Building Ltd, which is registered in England and Wales as company 15471719, and he carries out the wall survey and writes the price himself. If your cottage is listed, tell us when you ring and we start with the consent question. A verified customer left us 10 out of 10 on Checkatrade. Nothing is charged for the survey, or for the itemised written quote that follows it. 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.