Loft insulation in Alderholt

The top up comes first. Most of Alderholt went up on trussed rafters, and the pattern inside is the same in nearly all of them. One layer of mineral wool pushed down between the joists when the house was built, compressed and settled ever since, patchy at the edges and gone altogether in the far corners.

It is doing something. It is not doing enough. Over it goes a second layer of roll, cross laid across the joists at right angles to the first, so the timber stops working as a cold bridge. Two layers, about 270mm finished, is the depth a renovated ceiling is expected to reach.

The joists set what the first layer can be. They are rarely deep enough on their own, so a roll laid flush with the top of the timber gets nowhere near that, and anyone who lays one layer between the joists and calls it finished has sold you half a job. A trussed roof is full of bracing, so we work off a crawl board out from the hatch rather than walking about. An older cut roof with purlins gives room to move and takes deeper material.

The eaves stay open. Insulation stops at the wall plate and never goes past it. Push it into the eaves and you close the air gap the roof breathes through, and a roof that cannot breathe puts the moisture back onto the underside of the felt. A vent tray at each rafter lets the material run out to the edge without blocking anything, and the cross ventilation from soffit to soffit gets checked before any depth is added. Where the underlay is old bitumen and the soffits are boxed solid, a ridge vent is what fixes it.

Boarding, and keeping the loft usable. Boards laid straight onto joists are the commonest fault in an Alderholt loft, because they flatten what is underneath and flat wool insulates about as well as a carpet. Loft legs carry a raised floor clear of the second layer, we board a platform at the hatch and out to where you put things, and the hatch itself is insulated and draught sealed.

What else lives up there. Downlighters take fire rated covers first, and cables are clipped above the new layer rather than buried, because wiring buried in insulation runs hot. A cold water tank and its pipework have just been put out in the cold, so they get lagging in the same visit. We will talk you out of the whole thing where the loft is wet, where the material is contaminated with droppings, or where there is already a room in the roof with sloping ceilings and a dormer, because there the work belongs at rafter level as a warm roof build up.

The floor area of a loft is simple to work out. The edges, the hatch and what is already up there take the time.

Getting up there. A bungalow with the hatch in the hall is the easy one, and bungalows are a good share of the houses in Alderholt. A chalet with a room already in the roof leaves only the eaves voids, reached through small doors on your knees. A hatch above the stairwell of a two storey house needs a platform before anyone goes up, and a boarded loft has to be lifted and relaid.

What is already there. Old wool that is compressed or dirty is bagged and taken out, and stored boxes have to be shifted. Joists at even spacing with a clear run go quickly, while a trussed roof full of diagonal bracing means cutting every roll round the timber.

Ventilation and the edges. The mineral wool is stopped short at the wall plate so air can still come in at the eaves, otherwise the loft gets warm and wet together. Most of the labour goes on the corners, the hatch lid, boxing round downlighters and lagging any pipe that is now on the cold side. Approved Document L sets the depth to aim for.

Ask others how many layers they lay, whether the old wool comes out, and how they keep the eaves open.

Lofts in Alderholt, Daggons and Cripplestyle are on our patch, as are Sandleheath, Cranborne and Verwood, and building control here sits with Dorset Council. The journey from Boscombe is 12.5 miles. Behind the work is Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719. Before you book a visit in Alderholt, you can read our customers' Google reviews, word for word, on our reviews page.

The owner, Thomas Hannen, climbs through your hatch, sees the loft for himself and puts the price together. On Checkatrade, one verified customer has marked us 10 out of 10. Visiting costs you nothing, and neither does the written quote, which breaks down each item.

Most repairs in Alderholt 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.