Loft insulation in Three Legged Cross

Adding the second layer. A newer house came with one layer laid between the joists, and it is usually still where the builder put it. That is a better starting point than an old retrofit, but the timber is left uncovered and every joist runs heat through the ceiling. What is there stays, the settled patches are filled, and a new unbacked roll is cross laid over the top at right angles to it. Two layers get you to about 270mm, which is what a current U value asks for, and no timber shows.

What has to come out. Not much, in a newer house, but it is worth checking rather than assuming. Wool that is wet, compressed flat under boarding, patchy where somebody has crawled through it or contaminated with droppings is bagged in the loft and taken away rather than covered over. Older properties in the village can also have loose fill that has migrated into the eaves and closed them off.

Trusses, and moving about. These roofs are trussed, so there is bracing to work around and the ceiling ties are shallow. Nothing gets cut, notched or unbolted to make the job easier. We work off boards laid across the joists, feed the material through the truss webs, and do the far corners before the near ones, since the last corner reached is the one that ends up short of depth.

The eaves. The insulation runs out over the wall plate and stops there, with a vent tray in each rafter bay holding the air gap open so cross ventilation still crosses the loft. Modern roofs are laid on a breathable membrane, which is more forgiving than old bitumen felt, but they are also tighter than an old unfelted roof and they rely on the eaves. Push material into that edge and you get condensation on the underside of the covering and mould along the timbers within a winter.

Services, storage and roof rooms. Recessed lights are common in houses of this age and every one gets a fire rated cover, with cable and wiring lifted and clipped above the new layer rather than buried in it. Where there is a tank, it and its pipework are lagged and a lid fitted. Storage goes onto loft legs as a raised floor so the full depth stays uncompressed, with a platform at the top of the loft ladder, and the hatch gets an insulated board and a draught seal. A room in the roof, a dormer or a sloping ceiling is rafter level work instead: rigid board such as Celotex between the rafters, the air gap kept open above, PIR beneath and the vapour control taped through.

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 modern semi with a landing hatch and a fitted ladder, a bungalow with the opening in a hall ceiling, and a loft already boarded out and in use are three different half days before a roll 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.

Four in ten homes here went up in the twenty five years or so before the financial crash, which is recent enough that most owners assume the loft was done properly and never look. The material up there is usually still neat, still dry and still exactly as deep as the day it was laid, and that is the problem. What counted as enough when the house was built is well short of what is expected now, and it was laid between the joists rather than over them, so the timber has been leaking heat through the ceiling ever since.

It also means the work is simple and quick here, which is worth knowing before you put it off. There is rarely anything to clear out, the roof space is dry, and the second layer goes straight over what is there. The two things that do need attention are the eaves, because a builder laying to the standard of the day often stopped at the wall plate rather than reaching over it, and the boarding, because a lot of these lofts were boarded for storage straight onto the ties. Lift that onto legs and the depth underneath stops being wasted.

We cover Three Legged Cross, Verwood, West Moors, Woodlands, Alderholt and the BH21 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.