Loft insulation in Verwood

Judging what is there. A layer put in when a house was built in the eighties is usually still dry and still doing something, and if it is even, lofted and clear of the wall plate we can cross lay straight over it and count the depth. What rules it out is thinning where it has settled, a floor that has compressed it, patchy holes cut round old wiring, droppings from birds that have got in, or a bare foot of plasterboard showing at the wall where the wool is missing. Any one of those and it comes out, into bags at the hatch and away in the van, rather than being sealed under new material where interstitial damp can gather.

Building the depth. The new run is laid across the joists at right angles to whatever is between them, so the timbers stop bridging cold into the rooms below. Two layers, finishing near 270mm. Approved Document L is where that number comes from. The open runs get rolls of mineral wool, whether the merchant sells it as glass wool or as rockwool. Batts drop into the bays that truss bracing creates, loose fill goes where a roll cannot follow, and sheep wool is available if you would rather. The number that matters at the end of it is the U value across the ceiling, which is the biggest route out for heat in a house of this age, and it lands on the heating bill first and an EPC later.

The corners of a trussed roof. Nearly all the roofs of this age are trussed, which means a lattice of thin braced timbers rather than a space you can walk in. Access is the hatch, everything is fed in from there and worked outwards, and crawl boards move along with us. It is work at height from the first rung of the ladder. The middle of a loft like that is quick and the last two metres into each corner take the time, which is exactly where a hurried job stops short.

Ventilation, and where it comes from. The wool stops dead on the wall plate. The air gap above it is the inlet for the whole roof and vent trays hold it open, so a suitcase pushed into the eaves later cannot close it. Cross ventilation starts there, works its way up the slope and finds its way out under the ridge, faster still where a ridge vent has been fitted. A breathable membrane hands a modern roof a second route out. The bitumen felt underlay on an older one hands it nothing. Insulating the ceiling takes the dew point up into the roof, so eaves that get packed repay you with condensation, wet wool and black mould on the timbers instead of a warm bedroom.

Tank, lights and storage. The cold water tank is lagged and so is the pipework running to it, because the loft is now a colder place than the one the tank has sat in for forty years. Wiring and cables are brought up onto the insulation. Fire rated covers go over recessed lights and downlighters. You keep the storage as well: legs raise the deck above the work, the boarding goes back on top of them, and the loft ladder is set to meet the platform. A rigid board and a draught seal go onto the hatch. Where a garage or a roof has been converted into a room there is no floor to lay on, so that part goes in at rafter level. The rafters take board between them, PIR or Celotex, with a clear run of air kept over the top. Under the rafters goes a second layer, then taped vapour control, and multi-foil quilt only where a sloping ceiling or a dormer cheek is too shallow for anything thicker.

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 wide 1980s bungalow with a trussed roof, a chalet bungalow with rooms already in the roof, and a house with a fully boarded loft 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 Verwood, Three Legged Cross, West Moors, Alderholt and the BH31 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.