Wall insulation in Corfe Mullen

Reading the cavity comes first. A borescope through a 12mm hole tells you more than any survey from the pavement. We are looking at the width of the cavity, whether it is bridged with mortar snots, whether the existing fill has slumped, and whether anything in there is wet. Nothing gets specified before that, and any quote written without it is guesswork.

Filling a cavity properly. Where the cavity is clear, dry and wide enough, it is drilled on a pattern, filled and made good in a day on a normal Corfe Mullen house, with the fill installed by a registered installer who issues the CIGA certificate. Bonded polystyrene bead flows around wall ties and stays where it is put. Blown mineral wool is the older method and still fine in a sheltered, clean cavity. The choice is about the wall and the elevation, not about preference. External wall insulation, EWI, is the other route where a wall cannot take fill, but it changes the look of the house.

Fill that has slumped. Mineral wool blown into a Corfe Mullen wall decades ago settles under its own weight. What you get is a wall that is insulated at the bottom and empty at the top, and that shows up as a cold band and black mould near the ceiling. The fix is extraction, which means drilling out and vacuuming the old material, then refilling.

A wet cavity. If fill has bridged the gap, or a wall tie is loaded with mortar, driven rain crosses to the inner leaf and you get penetrating damp that follows the weather. That one is not solved by more insulation. It is solved by finding the bridge, and sometimes by taking the fill out of that elevation and dealing with the wall instead.

When the wall cannot take fill. A few of the older properties in Corfe Mullen are solid brick with no cavity at all, and a handful of cavities are simply too narrow. Those get internal wall insulation, IWI, instead: insulated plasterboard bonded to the masonry, or a batten and stud frame filled with mineral wool. PIR laminate boards such as Celotex or Kingspan do the work in the thinnest depth, with the vapour control layer taped so warm air cannot get behind them.

The junctions. Reveals at every window and door, the floor junction, the eaves and the joist ends decide whether the job feels like anything. A cold bridge left at a reveal is a thermal bridge, and it collects condensation whatever the u value of the wall beside it, so reveals get a thin board and any party wall gets a cavity barrier so bead does not disappear next door.

Ventilation and draughts. Filling a cavity tightens the house, and the moisture your family makes has to go somewhere. Trickle vents, working extract fans and air bricks left clear are part of the work rather than an extra, because airtightness without ventilation is how a dry house turns damp, and Approved Document F sets what is expected. Sealing draughts around the same time is what turns a thermal improvement into a room that feels different, and what moves an EPC.

We do not price cavity work by the square metre. What is inside the wall and what happens round the openings decide it.

What is in there. An empty cavity that is dry can be injected quickly. Old fill that has sunk, left voids or taken on water has to be sucked out before refilling, which is a far bigger job. A wall with no cavity cannot be injected at all, and needs lining inside or insulating outside.

Getting to it. A detached house off Wareham Road, a semi on one of the estates and a bungalow with a long low perimeter each need their own access plan. A bungalow can be drilled from steps or a tower, while a gable is done from a scaffold, as the work at height rules require.

Weather. A wall facing the prevailing rain stays wetter, and not every fill material suits an exposed wall.

Openings and edges. Round the reveals of windows and doors, at floor level, at the eaves and along a shared party wall is where heat leaks, and where a poor fill shows up as cold patches on the plaster.

Ask any other installer whether they looked in the cavity with a borescope, whether old fill is coming out, which material is going in, how ventilation is kept, and how the holes are made good.

We cover Corfe Mullen, Lockyers, Higher Blandford Road and the Wareham Road side, broadly BH21, about eight and a half miles from Boscombe, under Dorset Council. The borescope survey and the price both come from Thomas Hannen, who owns the business, and he will show you the camera picture of your cavity.

Bournemouth Roofing & Building Ltd is registered in England and Wales; the company number is 15471719. A verified customer marked us 10 out of 10 on Checkatrade. There is no charge for the survey or for the written quote, which lists each item. Before you book a visit in Corfe Mullen, you can read our customers' Google reviews, word for word, on our reviews page.

Most repairs in Corfe Mullen 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.