Loft insulation in Thorney Hill

The laying part is not complicated. One layer between the joists, friction fitted so there is nothing open at the sides. A second cross laid over the joists at right angles so the timber is buried and stops conducting heat down into the room. Around 270mm all in is what a renovated ceiling is expected to reach under Part L in Approved Document L, and the second layer is where most of the gain in the U value sits. Mineral wool roll along a clear run, rockwool batts where an older cut roof puts every bay at a different width, glass wool, sheep wool if you would rather, loose fill in the corners, and PIR rigid board such as Celotex or a multi-foil quilt where the headroom has simply gone. Then the fittings: fire rated covers over recessed lights and downlighters, cable and wiring lifted above the new layer instead of buried in it, lagging on the cold water tank and its pipework, and a board and draught seal on the hatch.

Boarding straight onto the joists. It is the commonest request and it undoes the job. Chipboard screwed down compresses the wool underneath to a fraction of its depth, so the part of the ceiling you crush is the part over the room you use most. Storage goes back on loft legs, with a raised floor clear of full depth and the boarding kept to the platform you actually need. If the joists will not carry the loading we say so before anything is fixed, and the loft ladder is reset to the new height.

Packing the eaves. The second habit, and the expensive one. Insulation is meant to run out over the wall plate and stop, with a vent tray at each rafter keeping an air gap open above it so cross ventilation can carry moisture from one side of the roof to the other. Push it on into the corner to make it look finished and the roof stops drying: the dew point moves into the layer, interstitial condensation forms out of sight, water gathers on the underside of the felt and black mould works down the rafters. Where the eaves are boxed and cannot be reopened, a ridge vent or a run of tile vents does the job from higher up, and a breathable membrane changes the detail rather than the requirement.

Laying over material that is wet. The third. New wool on top of damp wool hides the problem and doubles the cost of fixing it later. Anything that has settled and gone patchy but is dry and sound stays and gets levelled out. Anything damp, anything broken down into dust and anything contaminated with droppings is bagged in the loft and taken away, and we find out why it was wet before anything replaces it. Occasionally that means the honest answer is to fix a slipped tile or a fan discharging into the roof first and do the insulation afterwards, and we would rather say that than sell you material twice. Where the roof has already been converted to a room in roof, none of the floor work applies and it becomes a warm roof at rafter level instead, with taped joints, a vapour control layer and the sloping ceiling and dormer cheeks done properly.

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. An old cottage with a small trapdoor in a back bedroom, a detached house with a proper loft ladder, and a bungalow with a shallow roof you can only crawl through are three different jobs, and the access alone is work at height. 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.

Addresses here sit inside the New Forest National Park, so the planning authority is the National Park Authority rather than the district council, and the National Park property map is where you check any particular address. There is no conservation area over the village and barely anything on it is listed, so for most houses the constraint is not heritage consent. It is the Park's interest in how things look from outside.

For this job that interest reaches almost nothing. Insulation over a ceiling is inside the building, invisible, and needs no application to anybody. The one place it can touch is ventilation. If a roof has soffits that are boxed in and cannot be opened, the neat answer is vents in the slope or along the ridge, and those do show. Permitted development rights are narrower inside the Park than outside it, so that is worth establishing before the work rather than after. In practice we would rather take the air at the eaves anyway, which keeps the roof looking exactly as it does now and saves the conversation altogether.

We cover Thorney Hill, Bransgore, Burley, Burley Street, Sopley and the Bransgore side of the forest, and the BH23 addresses around them, with the New Forest National Park Authority for planning and New Forest District 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.