Loft insulation in Christchurch

What is up there now. Most Christchurch lofts have something in them and very few have enough. It has settled, it is compressed wherever anybody has knelt or stored boxes, it is patchy in the middle and missing at the edges, and there are gaps where cables and pipes were pulled through. Dry and even, it stays and we lay over it. Damp, black underneath or contaminated with droppings, it comes out, gets bagged and leaves with us.

Material, chosen for the space. Mineral wool for most lofts, as a soft glass wool roll, or a rockwool batt where something denser suits. Loose fill where the joists run at awkward centres or a trussed roof is too tight to work a roll into, and sheep wool if you would rather. Where headroom runs out it becomes PIR rigid board, cut tight and taped at the joints, with a multi-foil quilt for the shallowest corners.

Two layers, the second one crossways. A single layer laid flush between the joists gets a ceiling perhaps a third of the way and leaves every timber conducting heat straight through it. So the first layer goes between the joists and the second is cross laid over the joists, running the opposite way to the first. Around 270mm all in, which is roughly what the Part L U value means once it is wool rather than a number on a page, and the biggest reduction in heat loss most of these houses have left to make.

Ventilation, and the moisture that follows it. It is taken out to the wall plate and stopped there. The eaves stay open vent trays hold the air gap open above the quilt, so cross ventilation is not interrupted anywhere along the run, and where the eaves cannot be opened up a ridge vent is sometimes the answer. Block them and the vapour that used to leave the roof space condenses under cold felt instead. Insulating moves the dew point upward, interstitial condensation forms inside the layer, and you get wet insulation and black mould spreading on the rafters. BS 5250, the moisture standard for buildings is the reference, and A breathable membrane moves the detail along, but the principle holds.

Services, hatch and rafter level. Recessed lights need a cover rated for the job, not wool laid straight on, cables are clipped above the new depth instead of buried, and any cold water tank and its pipework want lagging once the space around them is cold. The hatch is insulated underneath the loft side and sealed where it lands against draughts. Where there is no loft floor at all, a room in roof has to be done at rafter level, warm roof fashion, with the sloping ceiling and any dormer cheek carried through as one layer.

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 town house with a hatch over a stairwell, a post-war semi with a landing hatch, and a top floor flat where the only access is a communal hatch are three different jobs before anything is laid, and all of it 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 sea is close enough here to matter, and what it goes for is not the tiles but the metal. Salt settles on a roof and keeps it damp between showers, which corrodes nail heads, clips and fixings from the outside in. A covering can look perfectly sound from the pavement while what holds it down has quietly gone. The loft is the one place you can see that, because from inside you are looking at the underside of the whole roof at once.

So before the depth goes down we look up. Rust marks running down the underlay, daylight at a verge, a batten that has gone soft, damp staining that follows a line rather than a patch: all of it is easier to read now than after 270mm has been laid over the floor. It matters more than it sounds, because insulating properly makes the roof space colder, and a small defect that used to dry out in a cold loft will not dry out in a colder one. Where we find something, you get a photograph of it and a straight answer about whether it needs doing first, at the same time, or not at all.

We cover Christchurch, Purewell, Somerford, Mudeford, Burton and Highcliffe, and the BH23 addresses around them, with BCP Council covering 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.