Loft insulation in Sixpenny Handley

The morning goes on getting in and getting the old work out. Access is a single hatch, the ladder is set and footed properly because it is work at height from the first rung, and crawl boards go down before anybody puts weight on a ceiling that may be lath and plaster. Then whatever is up there is judged. Wool that has settled to half its thickness, gone patchy round old wiring, been compressed under boards, gone missing at the wall or been contaminated with droppings is rolled, bagged at the hatch and carried down to the van. It does not get covered over, because a poor layer sealed under a good one is exactly where interstitial damp collects.

Before any new material goes down, the edges are sorted. Vent trays clip in between the rafters at the wall plate to hold the air gap open, so cross ventilation can start at the bottom of the slope and finish under the ridge, where a ridge vent gives it an exit. Behind the tiles, a breathable membrane will pass a little moisture. Bitumen felt underlay passes none, which is why on the older houses up here the eaves do all the work. Insulating a ceiling takes the dew point up into the roof space, and eaves that get packed repay you with condensation, wet material and black mould on the timbers.

The middle of the day is depth. Wool between the joists first, then a layer cross laid over them so the joists are covered rather than left standing in the cold, and the two finishing at about 270mm. That is what Approved Document L expects of a loft being renovated. Rolls of mineral wool, glass wool or rockwool, cover the open ground. Batts go into the bays that truss bracing makes. Loose fill is what reaches a shallow pitch, and sheep wool suits anyone who would rather keep mineral fibre out of the house. The number it all comes down to is the U value over your ceiling, the largest single route for heat loss out of a house, and you see the difference on the heating bill before an EPC ever catches up.

The last hour is everything else up there. The cold water tank gets lagging, and so does its pipework, because the loft is colder tonight than it was this morning. Wiring and cables come up onto the insulation rather than sitting buried under it. Fire rated covers go over recessed lights and downlighters. The boarding is rebuilt on legs so full depth runs on underneath it, the loft ladder is reset to the platform, and the hatch takes rigid board and a seal round the rebate.

Not every roof is a floor job. Where a room has been built into it there is nothing to lay on, so the work goes in at rafter level. PIR or Celotex is cut to the rafter bays, an air path is kept running above it, a layer is added beneath the rafters, and vapour control is taped across the room side. Where a sloping ceiling or a dormer cheek has run out of depth, multi-foil quilt is what fits. Where the covering is due to come off anyway, a warm roof over the deck does the job better than anything worked from inside.

There are things we would talk you out of, and they are worth saying. Do not board over a loft without lifting the deck onto legs first, because the boards will flatten whatever is underneath and you will pay for depth you never get. Do not stuff the eaves to stop a draught, because the draught is the roof breathing. And do not add depth to a loft that is already wet. Fix why it is wet, then insulate it, and it will still be dry in twenty years.

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 cottage with a void too shallow to sit up in, and a detached house on the edge of the village are three different jobs. 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 Sixpenny Handley, Pentridge, Cranborne, Tollard Royal, Woodyates and the SP5 addresses around them, with Dorset Council for planning and 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.