Wall insulation in Wool

Looking inside comes first. The borescope gives the cavity width, what material is in there, how far down it has dropped, whether the wall ties are bridged with mortar and whether the cavity is wet. It takes a few minutes and it is the difference between a quote and a guess. On a run of houses built together the answer is often the same next door, but we still look at yours.

A slumped fill. Loose material in a Wool cavity settles over twenty or thirty years. What you are left with is an empty band at the top of the wall, which is where most of the heat goes, and a packed, damp mass at the bottom, which is where the water crosses. That is why a failed fill can be worse than a cavity that was never touched.

Extraction and refill. The old material comes out through openings in the lowest course, the cavity is cleaned out, the ties are looked at while it is open, and the wall is made good. Then a new fill goes in, bonded bead or blown mineral wool depending on the exposure of the elevation. We do not offer a guarantee scheme of our own. A fill by a registered installer normally carries a CIGA certificate, so ask whoever drills your wall for it.

When we would leave the cavity alone. A wet cavity, a badly exposed elevation, bridged ties, or an outer leaf with open joints and blown render. In those cases the honest sequence is to repair the outer leaf, let the wall dry, and insulate afterwards or from inside instead. Filling a wall that is already letting penetrating damp through simply moves the problem indoors.

Solid walls in the older part of Wool. Nine inch brick and rubble stone with nothing to fill. Internal wall insulation means insulated plasterboard on a continuous adhesive bed, or PIR such as Celotex or Kingspan on battens or a stud, taped and skimmed to BS 8000-8. External wall insulation means boards and render over a render carrier, which gives a better U value but changes the look of the building.

The junctions. Reveals, the threshold, the floor junction, the eaves and the party wall are where the heat actually leaves and where condensation appears if they are skipped. Reveals take a thin board or aerogel, joist ends built into a solid wall keep air around them, and a lining that stops short at a party wall leaves a cold strip that grows mould.

Ventilation. A fill or a lining raises the inside surface above the dew point, which is what stops condensation forming, but the moisture still has to leave the house. Trickle vents, a working extract fan in the kitchen and bathroom and air bricks left clear go in with the work. Approved Document F sets the ventilation, BS 5250 covers interstitial moisture, and draughtproofing has the shortest payback of anything here.

You are mostly paying for what the survey finds and for the edges, not for the wall’s area. What is in the cavity. An empty, dry cavity in a seventies semi is a quick fill. A cavity already filled with material that has sagged or soaked up rain may have to be extracted before anything new goes in, which is slow. A solid wall in an older cottage cannot be filled at all.

The house. A mid terrace has only two outside walls, an end of terrace has a full gable as well, and a bungalow has walls all round that are easy to reach. Drilling a two storey wall needs a tower or ladder, as the work at height rules require. Lining inside is room by room, with furniture moved and put back.

Exposure. Walls facing south west, the exposed side in Wool, get the worst of the rain. A fill that is wrong for that exposure lets water track across to the inside face, so the product has to suit the wall.

Junctions. Window and door reveals, the floor junction, the eaves and any party wall are where cold spots and condensation appear if the detail is wrong.

Ask any rival quote whether the cavity has been checked with a borescope, which system and thickness they plan, and who makes good afterwards.

We insulate walls in Wool, East Burton, Bovington and along the road towards Winfrith, broadly BH20, 17.1 miles out from Boscombe. Planning and building regulations both go through Dorset Council. The work is done by Bournemouth Roofing & Building Ltd, company number 15471719 in England and Wales. Before you book a visit in Wool, you can read our customers' Google reviews, word for word, on our reviews page.

Thomas Hannen runs the business, drills the test hole, does the borescope check and writes the price himself, so the person who looked inside your wall is the one who quotes. On Checkatrade, one verified customer scored us 10 out of 10. We charge nothing for the survey visit or the itemised quote.

Most repairs in Wool 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.