Loft insulation in Winterborne Kingston

The outer metre first. On a roof this exposed that strip is where the money goes. The wool is taken the whole way out over the wall plate and stopped there, which on a shallow pitch means lying on your front to do it properly. A vent tray goes into every rafter bay above it so the gap stays open and ventilation still travels the length of the roof. Shut the eaves and the moisture that used to leave the roof has nowhere to go but the cold underside of the felt. The dew point ends up inside the material, interstitial condensation forms where nobody can see it, and by spring the wool is soaked and the rafter feet are black. Approved Document F carries the ventilation standard.

What is already up there. Old material settles, compresses, is patchy in the middle and missing at the outer edge, with a gap wherever a cable or a pipe was pulled through. If it is dry and still in one piece it stays put and the new work sits on top. If it is damp, blackened underneath or full of droppings, it is bagged at the hatch and taken away, and that appears as its own line on the quote rather than as a surprise at the end.

Choosing what to lay. Most of it is mineral wool: glass wool on the roll, or rockwool in batts, and where the joists were cut on site each piece is trimmed to its bay instead of being forced in. A ceiling that a roll will not lie flat on is better served by loose fill, poured or blown. Sheep wool if you want it. Once the headroom has gone, rigid PIR board cut tight and taped, with multi-foil quilt for whatever depth is left after that. Out at the exposed edge rigid board earns its place too, because there is nothing in a board for the wind to get into.

Two runs, and the second one turned. A single layer sitting flush between the joists leaves every timber taking heat straight out through the ceiling. So one run drops in between them and a second crosses them, square to everything underneath, and that second run is what breaks the bridge. Around 270mm in total is the u value Approved Document L sets for a renovated ceiling under Part L, expressed as a depth, and when it has been done properly you cannot pick out a joist top anywhere.

Fittings, hatch and rafter level. Every recessed light is given a rated cover so nothing rests against the fitting. Cable is run over the top of the new layer rather than through it, because wiring buried in wool runs warm. The cold water tank and the pipes serving it have just been left outside the warm part of the house, so lagging goes on. The hatch is boarded on its loft face and sealed, since an open one is a hole in the ceiling and a draught along the landing. Anything stored up there returns on loft legs standing above the wool. And where there is no loft floor to speak of, because the roof was turned into a room, the whole job belongs up at the rafters as a warm roof, sloping ceilings and dormer cheeks included.

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 cottage with a trapdoor in a back bedroom, a bungalow with a shallow roof you can only crawl through, and a house with a loft ladder into a clear open space are three different mornings before anything is laid, and getting in 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.

The weather here arrives from the south west with very little standing in its way, and that does something specific to a loft that nobody mentions when they sell you depth. Air driven in at the eaves does not stop at the wall plate. It runs along under the covering and blows through the open face of a soft quilt at the perimeter, stripping heat out of it the way wind strips it out of a jumper. It is why the cold patch on a ceiling below shows up as a band around the outside of a room rather than in the middle of it.

Adding more depth in the middle does nothing about that, so the perimeter gets treated as its own piece of work. The layer is carried right out over the wall plate rather than stopped a hand's width short, which on a shallow roof means working on your front to do it properly. Vent trays hold the air path open above it, because the answer to a draught is never to block the ventilation. And where the edge is badly exposed we finish the outer run in rigid board rather than soft wool, so there is nothing left for the wind to get into.

We cover Winterborne Kingston, Bere Regis, Winterborne Whitechurch, Milborne St Andrew, Anderson and the Winterborne villages, and the DT11 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.