Wall insulation in Stourpaine, without spoiling the wall

The survey that has to come first. A borescope through a single hole in a mortar joint tells us whether there is a cavity, how wide it is, whether it is clean, dry and clear, and whether anything has already gone into it. Everything after that follows from what the camera shows, and no quote should be written without it.

Cavity fill. Where the cavity is sound the wall is drilled on a pattern, the material blown in and the holes made good. Bonded bead is the safer choice on an older brick and block wall or a narrow gap, because it flows and it stays put. Blown mineral wool is fine in a clean, wide, sheltered cavity. Most houses are one day, all from outside, and it is the shortest payback of anything on this page. Part L sets what the finished wall is expected to reach.

Walls that should stay empty. If the camera finds a wet cavity, mortar bridging the gap, rubble in the bottom or no cavity trays over the windows, filling it is the wrong move. The fill carries water across to the inner leaf and you buy a damp problem in exchange for a small saving on heat loss.

Solid walls, which is most of the older village. A nine inch brick wall or a flint and rubble wall has nothing to fill and has to be insulated on one face or the other. It also has to be dry first, so gutters, ground levels and open joints get sorted before any insulation goes anywhere near it.

Internal wall insulation. Either insulated plasterboard on dabs where the wall is flat and modern, or boards on a treated batten and stud frame where it is not. PIR gives the most thermal performance per millimetre; wood fibre finished in lime gives less but lets an old wall keep drying. Joints taped, the vapour control layer continuous, the electrics brought forward.

External wall insulation. Insulation fixed to the outside, mesh and basecoat over it, then a silicone topcoat or a render carrier and a finish chosen to sit right on the building. It deals with the cold bridge at the joist ends and the eaves in a way an internal lining cannot, which is why it is worth asking about even where the answer turns out to be no.

The awkward edges. Reveals, thresholds, the floor junction and any party wall are where the labour goes and where a cheap quote goes quiet. A reveal too narrow for a normal board takes a thin aerogel laminate instead. Get those wrong and the condensation simply moves to the coldest strip you left behind.

Air, and old fill. A tighter house needs trickle vents, working extract fans and air bricks that are not blocked, to the rates in Approved Document F. Where a previous fill has slumped, or the cavity is wet, we extract it, dry the wall and give an honest view on refilling.

Same team from first visit to last, one person to ring, and no sub-contracting your work out to somebody you have never met. The quote is itemised, not a figure on the back of a card: the survey and any borescope check, the system and its thickness, making good around windows and doors, ventilation works, and disposal on separate lines, so you can compare it properly against anyone else's.

Nothing is left open or unusable overnight. The site is swept at the end of each day rather than the end of the job, and what comes out leaves with us. If something turns up once we start that nobody could have seen, you get a photograph and a price before we carry on.

Insulation on the inside of a wall is not development, as the Planning Portal's insulation guidance sets out, and that holds inside the conservation area as well. Cladding or rendering over the outside is a different question here, and Dorset Council keeps the record of what is designated. Regulation 23 brings the whole wall up to the current standard once you renovate more than half of it, so building control has a say even where planning does not.

Ring rather than use the form. Damp patches or black mould appearing on an outside wall after cavity fill or internal lining usually means water is tracking across the cavity, or warm air is reaching a cold surface at a junction. We look before we take anything out, because the fix depends on which of those it is. Say when the damp first showed and whether anything was done to the wall in the year before it, because that usually points straight at the cause. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.

Call now: 07435 839745

Stourpaine has its own conservation area, and it changes one wall decision in particular. Inside the boundary, appearance is controlled: replacing render like for like is maintenance, but adding 70 or 100mm of insulation and a new finish over the front of a house is a change of material and of proportion, and it needs an application. Dorset Council holds the designation records and will tell you whether your address is in it.

It is not a blanket no. External wall insulation on a rear elevation that nobody sees from the lane is a very different application from one on a flint frontage, and we have found the conservation officer far more interested in what the finish looks like and how deep the reveals end up than in the insulation itself. The killers are usually the eaves overhang, the window reveals going from crisp to clumsy, and a plastic looking topcoat on a village street of lime and flint.

Where the outside is off the table, the work goes inside, and then breathability matters more than it would on a modern house. That points at wood fibre and lime rather than a foil faced board, and at doing the coldest rooms properly instead of every room thinly.

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