Wall insulation in Matchams

Solid, or is there a cavity in there? Rendered, a nine inch solid wall and an early brick and block cavity are indistinguishable, and on a property built or extended in stages both can turn up on the same house. So the scope answers it rather than the eye: gap or no gap, what width, clean or fouled, dry or wet, empty or already filled.

Does the answer change round the corner? Frequently, yes. A Matchams extension put on twenty or thirty years after the original is often a different construction altogether, so the scope goes in more than once and the elevations get compared against each other before anything is written down.

Is the gap worth filling? If a Matchams cavity is clear, dry and wide enough, then yes, and it is filled from outside through drilled holes made good in matching mortar. Bead is the choice on anything exposed, because bonded polystyrene finds the corners and will not slump back out of them. Wool, blown in, is the older material and still correct behind shelter. Most properties are a day, and a low building sits within reach of a tower.

When is the answer no? Under fifty millimetres of gap. Mortar droppings bridging the ties. A cracked or open jointed outer leaf. Damp already crossing. Any of those and filling makes the house worse rather than better. On the most exposed wall of an isolated building we would sooner repoint and repair the outer leaf, then line that room internally, than blow material into a wall still taking water.

What goes on if we are lining? Internal wall insulation covers a solid wall and covers every cavity ruled out above. Insulated plasterboard bonded on, or batten and stud packed with mineral wool or PIR, then boarded and skimmed. Per millimetre Celotex and Kingspan do more, and aerogel board is for a room with no depth to surrender. Reveals, threshold, floor junction and joist ends get wrapped, since that is where the heat loss in a lined room concentrates.

Is the outside face an option here? Often it is the strongest one. External wall insulation puts board on the outer face with a render carrier and a thin coat over it, so on an exposed building it insulates and weatherproofs in a single operation and lifts the thermal bridge off corners and eaves. It also thickens every reveal and moves sills, vents and rainwater goods outwards, which makes it a bigger undertaking than a fill and one that wants planning settled on paper before materials are ordered.

And what happens to the air? Fill that has slumped shows as a cold band at the head of the wall, while a wet cavity brings penetrating damp inside and black mould with it. Both read off the borescope, and extraction comes before anything is put back. Ventilation follows: trickle vents, an extract fan that shifts air, air bricks kept clear. Insulating moves the dew point and strips out the draughts, so a taped vapour control layer and breathable materials keep interstitial condensation out of the build up.

The wall area is the simple part. Which way it faces and what happens at the openings are not. Which way the wall faces. The most exposed walls in Matchams face south west. A filled cavity in a wall soaked by driven rain can carry water across to the inner leaf. So on an exposed face we check the pointing and any render first, and sometimes advise lining that face from inside instead of filling it.

Cavity or solid. An empty, dry cavity is quick to fill. A solid wall has no gap to fill, so the choice is insulated board inside or a system outside, and both are larger jobs. The borescope answers this before any figure is written.

The openings. Window and door reveals, the floor edge and the eaves are where heat leaks and condensation gathers if the detail is skimped. They take the time.

The platform. A tower or a scaffold, as the work at height rules require.

Ask any rival quote whether they looked inside the wall or assumed, which product and how thick, how the reveals are finished, and who makes good the plaster.

Thomas Hannen owns the business and does the borescope survey and the pricing himself. Matchams is roughly five and a half miles out from Boscombe. We work there and on the Hurn Road side, in Avon and on the BH24 addresses along the heath, and Dorset Council deals with planning and building control for all of it.

Your contract would be with Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719. One customer has left us a verified 10 out of 10 on Checkatrade. Visiting and quoting cost you nothing, and the quote comes itemised. Before you book a visit in Matchams, you can read our customers' Google reviews, word for word, on our reviews page.

Most repairs in Matchams 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.