Wall insulation in Spetisbury
More than half the village is semi detached or terraced, and in a joined house the wall you share decides as much as the walls you do not.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
In a semi or a terrace you can only insulate your own half. A cavity fill has to be stopped at the party wall so the material stays in your cavity, and the junction where that party wall meets the outside wall is a cold spot in its own right. Both of those are worth knowing before anybody drills a hole.
The calls here are usually one of three. A joined house where one room is always colder than the rest. An older cottage with solid walls that will not hold heat however the boiler is set. Or damp showing on an outside wall after a fill went in some years ago.
We look before we price. One drilled hole and a borescope tells us whether there is a cavity, how wide, whether it is clear and dry, and whether anything in it has slumped. On a solid wall we look at the thickness, the pointing or render, and where the floor joists are built in. Then it is a written itemised quote with the survey, the system, the junctions and the ventilation on separate lines, and both the visit and the quote are free.
The work
What we fill, what we line, and where we stop
The borescope check. One small hole, a camera, and a straight answer about what you have. Clear, dry and wide enough is a fill. Bridged with mortar, already wet, or too narrow is not. Nobody can read that from the pavement and no honest quote is written without it.
Stopping the fill at the party wall. On a semi or a terrace the cavity often runs past the party wall into next door. A fill has to be contained, either at an existing cavity barrier or by forming one, so your material stays where you paid for it and does not end up in a neighbour's wall. Where work touches the shared structure, the party wall rules tell you what notice is owed.
Bead and mineral wool. Bonded polystyrene bead is blown through a drilled pattern and sets so it cannot settle later. Blown mineral wool is water repellent and long established, and is a fair choice on a sheltered wall with a sound outer leaf. Holes are made good in a matched mortar and a house is normally a day.
Solid walls. Around a fifth of the homes here were built before the cavity became standard. A nine inch brick wall has nothing in it to fill, and injecting one achieves nothing. The choice is internal wall insulation or external wall insulation.
Internal wall insulation. Insulated plasterboard bonded and fixed to a flat wall, or PIR board such as Celotex or Kingspan between battens or a stud, then boarded and skimmed. Radiators, sockets and skirtings come off and go back. On a wall that must breathe we build in wood fibre and lime instead of a vapour tight sandwich, so moisture can leave rather than stall in the build up.
External wall insulation. Board mechanically fixed outside, a render carrier and mesh over it, then a through coloured finish. It keeps the masonry warm, so interstitial condensation has nowhere to form, and it costs no floor area. It changes the appearance of the house entirely.
Junctions. Reveals at windows and doors, the threshold, the floor junction, the eaves and the joist ends built into the wall. A shallow reveal takes a thin aerogel board. Skip these and you have made a cold bridge, and a thermal bridge is where the dew point lands and black mould starts.
Failed fill and ventilation. A fill that has slumped or wetted up is extracted through drilled holes and the cavity dried. Then trickle vents, a working extract and air bricks kept clear, because Approved Document F expects a tighter house to still be able to breathe.
How it runs
From your call to a written price
Same team from first visit to last, one person to ring, and no sub-contracting your work out to somebody you have never met. The quote is itemised, not a figure on the back of a card: the survey and any borescope check, the system and its thickness, making good around windows and doors, ventilation works, and disposal on separate lines, so you can compare it properly against anyone else's.
Nothing is left open or unusable overnight. The site is swept at the end of each day rather than the end of the job, and what comes out leaves with us. If something turns up once we start that nobody could have seen, you get a photograph and a price before we carry on.
Dorset Council is the planning authority. Insulating the inside face of a wall is not development and needs no permission, which the Planning Portal confirms. External wall insulation is different because it changes the outer face. There are 18 listed entries in and around the parish and no conservation area over the village, and where a building is listed consent covers internal work as well. Building control comes in under regulation 23 once a thermal element is renovated, and Part L sets the U value.
Cost
What decides the price of a wall insulation job
No rate per square metre, because the wall area is the easy part; what happens at every window, door and floor junction is not.
Getting to it. A pair of semis off the main road, a terrace of three with shared cavities, and a solid walled cottage near the church are three different jobs before anything is drilled. Cavity fill is drilled from outside and a bungalow comes off a tower where a three storey gable wants a scaffold. Internal lining is worked room by room from inside, so it is your rooms rather than a platform that gets disrupted. The work at height rules still set the platform.
Which wall you actually have. A cavity that is clear and dry can be filled in a day. A solid wall cannot be filled at all, and has to be lined inside or insulated outside, which is a different job at a different price. A borescope through one drilled hole settles it, and no honest quote is written before that.
The junctions, not the field of the wall. Reveals at windows and doors, the floor junction, the eaves and any party wall are where heat escapes and where condensation shows up if the detailing is wrong. That work is slow, it is most of the labour, and it is the first thing a cheap quote leaves out.
Comparing quotes? Ask whether the wall has actually been checked with a borescope or just assumed, what system and what thickness is specified, how the reveals and floor junction are being detailed, whether ventilation is being addressed, and who makes good the plaster and decoration afterwards. Two quotes for the same job are usually two different jobs.
If damp has appeared
Damp or mould after a wall was insulated
Ring rather than use the form. Damp patches or black mould appearing on an outside wall after cavity fill or internal lining usually means water is tracking across the cavity, or warm air is reaching a cold surface at a junction. We look before we take anything out, because the fix depends on which of those it is. If you are in a joined house, tell us whether the patch is near the party wall, because that is a different fault from one in the middle of an elevation. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
The wall you share, and the corner beside it
Somewhere over half the homes in the village are semi detached or terraced, and a joined house behaves differently from a detached one. The party wall itself loses you almost nothing, because there is a heated house on the other side of it. The problem is where that wall meets the outside wall, at the corner of the room. Masonry carries heat sideways, and that junction is often the coldest line in an otherwise warm room.
It is why the damp in a semi so often turns up in one corner rather than across a whole wall. A cavity fill in the outer wall does nothing for that corner, because the cold is coming through the return of the party wall rather than through the field of the outside one. The fix is a small internal lining returned along the party wall for a short distance, which breaks the thermal bridge and moves the dew point off the plaster.
The second thing is containment. Cavities frequently run straight past the party wall, and blowing a fill in without stopping it means paying to insulate somebody else's wall and leaving your own gable short. We check for a barrier and form one where there is none.
Who you are dealing with
A local firm you can check
We cover Spetisbury, Charlton Marshall, Sturminster Marshall and the villages along the Stour, broadly DT11, under Dorset Council. 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.
Questions
Spetisbury questions we get asked
Can I fill my cavity if my neighbour does not want theirs done?
Yes. The fill is contained at the party wall so it stays in your half. Where there is no barrier there we form one before anything is blown in.
Why is the damp always in the same corner of the room?
Because the party wall carries cold into that corner and the dew point lands there first. Insulating the outside wall alone will not cure it; the lining has to return a short way along the shared wall.
Do I need to tell my neighbour before work starts?
If anything touches the shared structure, yes, and the party wall rules set out what notice is owed. A straightforward fill contained on your side usually does not, but we will say so at the visit.
Our house has solid walls. Is external insulation allowed here?
On an unlisted house outside a conservation area it is usually a permitted alteration, though it changes the look of the building and we would talk it through with you first.
Does wall insulation move an energy rating much?
It normally does, because heat loss through the walls is a big share of the total, so the payback is real. We will not put a number on it, since that turns on how the house is heated.
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Get the walls looked at before anything is drilled
Thomas comes out, checks the cavity with a borescope and prices the wall, the junctions and the ventilation in writing. The visit and the quote are free.