Loft insulation in Sandleheath

Whatever is up there now. Most lofts on this patch have had something laid in them already, and the state of it decides the first hour. Settled to half the thickness it started at. Compressed flat under a boarded floor. Patchy where somebody has been at the wiring. Contaminated where birds have got in and left droppings, or simply missing for the last foot before the wall. None of that is worth keeping, so it is rolled, bagged at the hatch and carried out before a new roll is opened, and it leaves in the van. Covering a poor old layer with a good new one buries the trouble in the middle of the build up, where interstitial damp can sit for years without anybody seeing it.

What you are standing on. The ceiling under your feet is plasterboard at best, and on the older houses here it is lath and plaster, which will take no weight whatever. Crawl boards go down and move along with us, and nobody trusts a joist they have not looked at. Access is a single hatch from beginning to end, which makes the whole thing work at height, so the ladder is set and footed properly.

Depth, and the layer that runs the other way. With the deck clear, wool goes in between the joists and a second thickness is cross laid over the joists at ninety degrees to the first, so no timber is left proud to carry cold into the bedroom. Two layers, about 270mm all told, which is the figure Approved Document L sets for a loft being renovated. Nearly all of it is mineral wool, sold as glass wool or as rockwool, and both behave much the same once they are down. Rolls do the long clear runs, batts suit a roof chopped up by bracing, loose fill gets into places a roll cannot follow, and sheep wool is there if you would rather not have mineral fibre over your head. Depth is only the means. What you are buying is a lower U value across the ceiling, which is where the largest share of a house's heat loss goes, and you notice it on the heating bill well before it shows on an EPC.

The one gap that stays empty. At the outside wall the insulation stops on the wall plate and goes no further. The air gap above it is the inlet for the whole roof, and once it is stuffed the roof has no way of clearing the moisture rising out of the house. Vent trays clip in to hold that channel open. From there cross ventilation moves the air over the top of the wool and out under the ridge, quicker where somebody has fitted a ridge vent. A breathable membrane will let a little moisture through as well. Old bitumen felt underlay lets none. A loft that stayed dry for thirty years can show condensation, wet material and black mould on the timbers inside one winter if the edges get packed, because the space you have just made colder is where the dew point now sits.

Tank, cables, lights and the way in. Everything that used to live in a mild loft now lives in a cold one, so the cold water tank and its pipework get lagging the same day. Cables come up on top of the wool rather than sitting buried in it, and any wiring stapled down out of sight gets looked at while it can be seen. Recessed lights and downlighters set into the ceiling below take fire rated covers, so no fitting ends up with wool heaped over it. Where the space earns its keep, loft legs raise the boarding above the finished work and nothing underneath gets squashed, with the loft ladder reset to meet the new platform height. The hatch is the last thing done: rigid board on the top face, a seal round the rebate, and the draught that has been running up your stairs all winter stops.

Where there is no loft floor. A room in the roof has sloping ceilings and dormer cheeks instead of a floor, so the work moves up to rafter level. The air path comes first, held clear above the board so the timbers can still dry. Then rigid board, PIR or Celotex, cut tight between the rafters, a further layer under them, and the room side closed with a taped vapour control layer. Multi-foil quilt is the answer where a ceiling can give up almost no depth.

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 older cottage with a small hatch over the stairs, an estate semi with a trussed roof full of bracing, and a bungalow with a boarded loft full of boxes are three different mornings before any material is opened. 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 Sandleheath, Alderholt, Fordingbridge and the SP6 addresses around them, with New Forest District 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.