Wall insulation in Corfe Mullen, and what is already in the wall
Nearly every wall in the village is a cavity, and most were filled decades ago, so the real question is what is in there now.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
Sixty two per cent of Corfe Mullen was built between the war and the early 1980s, which means almost every wall in the village is a cavity wall. It also means most of them were pumped full of something a long time ago. So the question here is rarely whether your wall can be filled. It is what is already in there, and whether it is still doing anything.
The calls follow a pattern. A room on the gable end that has always been colder than the rest. Black mould in a band near the ceiling of a back bedroom. Or a damp patch on an outside wall that appears after a week of westerly rain and fades again in a dry spell.
We drill one small hole and put a borescope in before quoting anything, because that settles it in a couple of minutes. You see the cavity width, whether the fill is even or has dropped, and whether the material is wet. Then it goes into a written itemised quote. The visit and the quote are both free.
The work
Cavities that were filled once, and what is left in them
Reading the cavity first. A borescope through a 12mm hole tells you more than any survey from the pavement. We are looking for four things: the width of the cavity, whether it is bridged with mortar snots, whether the existing fill has slumped, and whether anything in there is wet. Nothing gets specified before that, and any quote written without it is guesswork.
Filling a cavity properly. Where the cavity is clear, dry and wide enough, it is drilled on a pattern, filled and made good in a day on a normal house. Bonded polystyrene bead flows around wall ties and stays where it is put. Blown mineral wool is the older method and still fine in a sheltered, clean cavity. The choice is about the wall and the elevation, not about preference. External wall insulation, EWI, is the other route where a wall cannot take fill, but it changes the look of the house.
Fill that has slumped. Mineral wool blown in decades ago settles under its own weight. What you get is a wall that is insulated at the bottom and empty at the top, and that shows up as a cold band and black mould near the ceiling. The fix is extraction, which means drilling out and vacuuming the old material, then refilling.
A wet cavity. If fill has bridged the gap, or a wall tie is loaded with mortar, driven rain crosses to the inner leaf and you get penetrating damp that follows the weather. That one is not solved by more insulation. It is solved by finding the bridge, and sometimes by taking the fill out of that elevation and dealing with the wall instead.
When the wall cannot take fill. A few of the older properties in the village are solid brick with no cavity at all, and a handful of cavities are simply too narrow. Those get internal wall insulation, IWI, instead: insulated plasterboard bonded to the masonry, or a batten and stud frame filled with mineral wool. PIR laminate boards such as Celotex or Kingspan do the work in the thinnest depth, with the vapour control layer taped so warm air cannot get behind them.
The junctions. Reveals at every window and door, the floor junction, the eaves and the joist ends decide whether the job feels like anything. A cold bridge left at a reveal is a thermal bridge, and it collects condensation whatever the u value of the wall beside it, so reveals get a thin board and any party wall gets a cavity barrier so bead does not disappear next door.
Ventilation and draughts. Filling a cavity tightens the house, and the moisture your family makes has to go somewhere. Trickle vents, working extract fans and air bricks left clear are part of the work rather than an extra, because airtightness without ventilation is how a dry house turns damp, and Approved Document F sets what is expected. Sealing draughts around the same time is what turns a thermal improvement into a room that feels different, and what moves an EPC.
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.
Corfe Mullen is under Dorset Council. There is no conservation area in the village and one listed entry in the whole of it, so this is a building control question rather than a planning one. Cavity fill and internal lining are both notifiable work, and where an existing wall is upgraded regulation 23 sets what the finished element has to reach under Part L.
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 detached house off Wareham Road, a 1970s semi on one of the estates and a bungalow with a long low perimeter are three different jobs before a hole 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. Corfe Mullen is seven miles from us and we are through the village most weeks, so an address here is normally looked at within a day or two. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
What forty year old fill looks like down a borescope
A third of Corfe Mullen went up in the 1970s and early 1980s, and a great many of those houses were filled under one scheme or another in the years that followed. Mineral wool blown into a 50mm cavity does not stay put for ever. It compacts, it bridges where the installer was heavy handed near a tie, and on the weather side it can hold water rather than shed it. That heat loss is not visible from the garden and all of it is obvious through the lens.
That changes what you should ask for. If somebody quotes you a cavity fill on a house of this age without opening the wall, they are proposing to blow new material on top of old material they have not seen. Where the existing fill is sound and even, the honest answer is that your walls are already done and the money is better spent on draughts or ventilation. Where it has dropped, extraction comes first and the refill is the second half of the job.
Who you are dealing with
A local firm you can check
We cover Corfe Mullen, Lockyers, Higher Blandford Road and the Wareham Road side, broadly BH21, 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
Corfe Mullen questions we get asked
How can I find out if my cavity was already filled?
One drilled hole and a borescope. It takes minutes and shows the material, how even it is and whether it is dry. Nobody should quote a fill without doing it.
My upstairs wall is mouldy near the ceiling. Is that the insulation?
Very often it is fill that has settled and left the top of the cavity empty, so that band runs colder than the rest and condensation lands on it. A borescope near the ceiling confirms it.
Is it possible to get old material back out of a wall?
Yes. The wall is drilled on a pattern and the material vacuumed out, then the cavity is cleaned and refilled or left clear, depending on why it came out.
How long does a cavity fill take, and how much mess is it?
A normal house is drilled, filled and made good in a day where the access is clear. The holes are made good in mortar matched to what is there, and the only mess is dust outside.
Bead or blown wool, does the choice actually matter?
On an exposed elevation, yes, because bonded bead does not wick water across the cavity and it holds its position. In a clean sheltered cavity mineral wool still does a sound job.
Will filling the cavity make my house damp?
Not on a wall that suits it. It goes wrong when a cavity that is too narrow, bridged or already wet is filled anyway, which is what the check is for.
Nearby, and next door
Wall insulation near Corfe Mullen
Wall insulation nearby
Our other trades in Corfe Mullen
Everything we do in Corfe Mullen Wall insulation, all areas Every area we cover
Free quote
Have the cavity looked at before anything goes into it
Thomas comes out, borescopes the wall, tells you honestly whether it needs anything and prices the work in writing. The visit and the quote are free.