Wall insulation in New Milton

The borescope check comes first. One hole in a mortar joint, a camera in the cavity, and we can see the width, what is already in there and whether the outer leaf is wet. New Milton is mostly brick and block with a nominal 50mm cavity, and the 1980s stock that dominates here often has a wider one.

Cavity fill in a terrace. Where a New Milton cavity is clear and dry it takes bonded polystyrene bead or blown mineral wool. The complication is that unless there is a cavity barrier on the boundary, material injected into your wall can travel into your neighbour's. We look before any drilling, and where there is none the installer fits one or limits the fill. The fill itself is done by a separate cavity installer, not by us.

End of terrace gables. The gable is the one wall in a New Milton terrace that faces the weather over its whole area, which is why the end house is always the cold one. It takes fill where the cavity allows and internal lining or external wall insulation where it does not, and on a gable an EWI system with boards, a render carrier and a thin coat finish gives the biggest drop in heat loss of anything available.

Internal lining, IWI. Insulated plasterboard fixed back to New Milton masonry, or a stud and batten frame with mineral wool or PIR board such as Celotex or Kingspan between it. Reveals returned, the floor junction carried down, joist ends thought about and a breathable vapour control layer taped so the dew point does not sit in the build up as interstitial condensation. Where a threshold has no room, an aerogel backed board does the same in a third of the thickness.

The party wall itself. Lining the face of a New Milton party wall is rarely worth much, because the home on the other side is heated too. What is worth doing is the junction, where the outside wall meets it and forms a cold bridge running the full height of the building. That corner is where black mould turns up, and it is cured by returning the lining along the party wall 400 to 600mm rather than stopping at it.

Failed fill. Slumped fibre in a New Milton wall leaves a cold band of heat loss at the top of the wall and a wet cavity holds damp against the inner leaf. Both are extracted through a drilled pattern, bagged and taken away, then refilled in bead once the wall is dry. On a mid terrace with one small elevation the payback on that is quick.

Ventilation. Extract in the kitchen and bathroom, trickle vents in the windows and air bricks kept clear. Approved Document F sets what the ventilation has to do, and it matters more the moment airtightness improves.

What the borescope finds. Nearly all of the town's post-war and eighties houses have a cavity, and plenty were filled years ago with whatever was used at the time. An empty, clean cavity is a quick blown-bead job from outside.

A partly filled one, or one choked with mortar snots and rubble at the bottom, has to be dealt with first. An older solid wall means insulated plasterboard inside or a board and render system outside, which is a different scale of job.

Driven rain on the seaward elevation. Filling a cavity on the south west face only makes sense if the outer leaf keeps water out. Where the pointing has eroded or the render is cracked, that repair comes first, or the fill carries damp across to the inner wall.

Detailing at openings. With internal lining, every window reveal, socket, skirting and radiator has to come off, be returned and refitted, and those junctions are where cold bridges and mould appear if they are rushed. They take far more of the time than the flat wall.

Access and neighbours. A mid terrace, a gable end and a flat in a block all need different platforms, and the work at height rules set how we work from them. On a terrace the cavity is closed at the party line so the fill does not run next door.

Ask anyone else pricing it: did they look inside the cavity, what material and thickness are they using, and who replasters and redecorates round the reveals?

We are based in Boscombe, and New Milton is eight miles out. We insulate walls in the town, Barton on Sea, Ashley, Bashley and across BH25; New Forest District Council oversees planning and building control.

You deal with Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719. The borescope goes in by Thomas Hannen's own hand, because it is his business and he prices each wall himself. On Checkatrade a verified customer gave us 10 out of 10. Nothing is charged for the survey visit or the itemised written quote. Before you book a visit in New Milton, you can read our customers' Google reviews, word for word, on our reviews page.

Most repairs in New Milton 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.