Loft insulation in Alderholt

The top up. Most of the village 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 up here, 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.

No rate per square metre, because the floor area is the easy part and the awkward edges are where the time goes.

Getting to it. A bungalow with the hatch in the hall, a chalet with a room already in the roof, and a detached house on one of the estates are three different mornings. A hatch on a landing you can stand a ladder under is one job. A hatch over a stairwell, a crawl space you can only move through on your knees, or a loft full of boarding that has to come up and go back, is time before any material is laid.

What is up there now, and what it is sitting on. Old material that has to come out, be bagged and taken away is a cost before anything new goes down, and so is a loft full of boxes that has to be emptied and put back. Joists at 400 centres with a flat run across them is a different afternoon from a trussed roof full of bracing.

Ventilation, and the edges nobody reaches. Insulation stops at the wall plate and the eaves have to stay clear, or you trade a warm bedroom for a wet roof. Getting depth right into the corners and around the hatch, boxing over downlighters and lagging anything that now sits in the cold, is most of the labour. Approved Document L sets what the work is expected to reach.

Comparing quotes? Ask what depth is actually being laid and in how many layers, whether the old material is coming out or being covered over, whether the eaves are being kept clear, what happens to anything you store up there, and whether the hatch and the pipework are included. Two quotes for the same job are usually two different jobs.

We cover Alderholt, Sandleheath, Cranborne, Verwood and the SP6 lanes either side of the county line, with Dorset Council for building control. You are dealing with Bournemouth Roofing & Building, the trading name of Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which you can look up in a minute. Thomas Hannen's business, and he is the one who comes out to price the job, not a salesman. A verified customer's 10 out of 10 on Checkatrade. The visit and the written quote are both free.