Wall insulation in Alderholt

External wall insulation wraps the outside of the house. Insulation board is mechanically fixed and bonded to the outside face, a render carrier with a reinforcing mesh over it, beads at every edge and reveal, then a through coloured silicone or mineral finish.

The masonry ends up on the warm side, so interstitial condensation has nowhere to form and the wall dries outwards. Rooms keep their size, and the work happens outside rather than through your house. Sills, downpipes, the eaves and the meter boxes all have to be dealt with, and that detail is where the time goes.

Internal wall insulation. Where the outside face has to stay as it is, insulated plasterboard bonded and fixed to a flat wall, or PIR board such as Celotex or Kingspan set between battens or a timber stud, then boarded and skimmed. On an old wall that has to stay breathable we use wood fibre and lime instead, so vapour can pass rather than stall behind a vapour tight face.

Cavity fill. On the newer stock, bonded polystyrene bead blown through a drilled pattern, or blown mineral wool where the wall is sheltered and the outer leaf sound. The cavity must be clear, dry and wide enough. The holes are made good in a matched mortar and a house is normally a single day.

Solid walls, which cannot be filled. A nine inch brick wall is not a brick and block cavity wall, however similar they look from the road, and there is nothing inside it to inject. That is the single most common misunderstanding about walls in Alderholt.

Junctions. Window and door reveals, the threshold, the floor junction, the eaves and the joist ends. On external work the insulation has to be returned into every reveal, and where there is no depth for a normal board a thin aerogel goes in instead. Leave one out and you have made a cold bridge, and a thermal bridge is where the dew point lands and black mould appears.

Failed fill. Where an earlier fill has slumped down the cavity, or wetted up because the outer leaf is cracking, it comes out through drilled holes and the wall dries before anything replaces it.

Ventilation. Trickle vents, a working extract in the kitchen and bathroom, and air bricks left clear. Approved Document F sets the expectation. Airtightness without ventilation turns a draughty house into a damp one.

Thomas checks the walls himself, drills one small hole and looks into the cavity with a borescope before he prices anything. The quote covers the survey, the system and its thickness, finishing round windows and doors, ventilation, and disposal. If a fill is right, ask who installs it and whether it comes with a CIGA certificate.

Most of Alderholt's eighties houses and bungalows have cavity walls, so the question is whether the cavity is empty and dry. The cottages are usually solid brick, which cannot be filled at all and has to be lined inside or insulated outside. Filling is done from outside, from a tower on a bungalow or scaffold on a two storey gable. Lining is done room by room, with floors sheeted, furniture covered, and everything cleared at the end of the day.

If the borescope finds rubble or old insulation already in the cavity, you get the photograph and a price before we do anything. Dorset Council is the planning authority. There is no conservation area here, and the parish's listed buildings, the Church of St James among them, stand on the edge of Alderholt, so insulating inside is not development and external wall insulation on an unlisted house is usually a permitted alteration, as the Planning Portal's external walls guidance explains. Building control applies under regulation 23, and Part L sets the U-value the wall has to reach.

Fresh damp or mould on an outside wall after insulation work usually comes from rain getting across the cavity or from room air condensing where the wall is colder, often at a corner or beside a window.

Photograph it, note the wall, and watch whether rain makes it worse. Keep the room aired, and leave the lining alone for now. On the first visit we work out which it is before anything comes out. Scheduled work runs Monday to Friday, 8am to 6pm. Ring us, as the form is slower, and if nobody picks up we will ring back as soon as we can.

Call now: 07435 839745

Alderholt has no conservation area, and the parish's few listed buildings stand at its edge, so most houses here are free of both controls. On most of the surrounding parishes at least one of those applies, and it removes an option: you cannot wrap the outside of a listed cottage in insulation, and inside a conservation area a change to the external appearance needs an application and often gets refused.

Where neither applies, external wall insulation becomes a real choice rather than a theoretical one, and on a solid wall it is usually the better engineering. The insulation goes on the cold side, so the masonry stays warm and above the dew point, which is precisely the opposite of what an internal lining does. You keep the floor area, you keep the plaster and the skirtings, and the disruption is outside rather than in the rooms you live in. Heat loss through a solid wall is one of the largest lines on an EPC assessment of an older Alderholt house like this, which is where the payback comes from.

It is not automatic, and we would not pretend otherwise. It changes the look of the house, it needs care at the eaves and the ground line, and on a semi it stops at the boundary unless a neighbour joins in. Roughly a fifth of the homes here predate the cavity wall, so this is a live question in the village, not an academic one. Have the conversation properly before defaulting to a lining indoors, and if the loft and floors are on the list too, insulating the whole house in Alderholt sets the order.

Nearby places we also cover for wall insulation, with straight-line distances from Alderholt, and the other trades we offer in Alderholt itself.

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