Insulation in Christchurch

Loft top ups on the estate houses. Almost a third of the housing here went up between 1983 and 2008, with the peak in the 1980s, and it was insulated to the standard of the day, which is roughly a third of what is expected now. Mineral wool, ordinary eco roll, goes down in two layers, the first between the joists and the second across them at right angles so the timber is not a cold bridge and a line of heat loss running through the middle of it. Between and over, to something like 250 to 270mm, which is where the loft stops being the weak point in the house and the 0.16 u-value a renovated element is expected to reach. Old wool that has settled stays where it is and counts towards the depth.

Top floor flats and maisonettes. Flats are 39.5 per cent of the dwellings in Christchurch, and the roof space over the top floor is usually the single reason that flat is colder than the one below it. The work itself is ordinary: a communal hatch off the landing, boards lifted where there is boarding, roll laid between and over, the hatch sealed and the tank lagged. What is not ordinary is who can instruct it, because the roof space and the structure normally belong to the freeholder rather than to you.

A fifth of the stock predates 1919, and those streets towards the centre have no cavity to fill, so a wall is either lined on the inside or insulated on the outside, EWI on a quote. Internal wall insulation, board on battens or a rigid board bonded to the wall, costs you an inch or two of room and nothing else. On any old solid wall the thing to get right is vapour, because a wall built to dry outwards has to be allowed to.

On the later stock the question is not whether to fill the cavity wall but whether somebody already has, and whether that fill has slumped or gone damp on the exposed side. Two kilometres from the water the seaward elevation takes the driven rain, and a fill that has bridged the cavity shows up as damp patches inside. That is a borescope check, not a guess from the pavement.

Where an attic has been turned into a room, or the house was built as a chalet with a dormer, rigid PIR board goes between and under the rafters, foil faced, cut tight and taped, with the air gap kept above it, or a multi-layer foil quilt such as TLX where a sloping ceiling has nothing to give away. Wool rammed into the eaves blocks that air path and turns a warm loft into a damp one, so vent trays go in at the eaves first, and Approved Document F is the standard on the ventilation side. Then an insulated, draught sealed hatch, lagging on the tank and on pipework now sitting above the warm layer, and covers over the downlighters.

A top floor flat with a small communal hatch on the landing, a town terrace with an opening over the stairs and a loft chopped up by party walls, and an estate house with a drop down ladder are three different jobs before any material goes down. Old material to bag and take away, storage to move and put back, and eaves that must stay clear all come first, and Approved Document L sets what the work has to reach. Comparing quotes, ask what depth is being laid, whether the old material is removed or covered, and whether the hatch and pipework are included.

We cover Christchurch and the roads around it, the town centre, Purewell, Somerford, Jumpers and Mudeford, and the BH23 addresses across them. 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.