Wall insulation in Wool
Most of the village was built with a cavity and a lot of those cavities were injected years ago, so the first job is finding out what is in yours.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
Over half the houses in Wool went up between the war and the early eighties, most of them with a cavity, and a great many of those cavities were injected later under one grant scheme or another. So the wall question here is usually not whether to insulate but what is already in there, how far up the wall it still reaches and whether it is dry.
The calls follow from that. A damp patch on an inside wall that only shows after a wet, windy week. Black mould in a bedroom corner that keeps coming back. A house bought recently where nobody can find any paperwork for the fill at all.
We drill one small hole in a mortar joint and put a borescope through it before quoting anything, and we look at the outer leaf, the pointing and the ground level while we are there. The site visit is free and so is the written itemised quote.
The work
Cavities that were filled once already
Looking inside first. The borescope gives the cavity width, what material is in there, how far down it has dropped, whether the wall ties are bridged with mortar and whether the cavity is wet. It takes a few minutes and it is the difference between a quote and a guess. On a run of houses built together the answer is often the same next door, but we still look at yours.
A slumped fill. Loose material settles over twenty or thirty years. What you are left with is an empty band at the top of the wall, which is where most of the heat goes, and a packed, damp mass at the bottom, which is where the water crosses. That is why a failed fill can be worse than a cavity that was never touched.
Extraction and refill. The old material comes out through openings in the lowest course, the cavity is cleaned out, the ties are looked at while it is open, and the wall is made good. Then a new fill goes in, bonded bead or blown mineral wool depending on the exposure of the elevation. We do not offer a guarantee scheme of our own; a cavity fill is normally installed under an independent one, so ask whoever drills your wall which scheme covers it.
When we would leave the cavity alone. A wet cavity, a badly exposed elevation, bridged ties, or an outer leaf with open joints and blown render. In those cases the honest sequence is to repair the outer leaf, let the wall dry, and insulate afterwards or from inside instead. Filling a wall that is already letting penetrating damp through simply moves the problem indoors.
Solid walls in the older part of the village. Nine inch brick and rubble stone with nothing to fill. Internal wall insulation means insulated plasterboard on a continuous adhesive bed, or PIR such as Celotex or Kingspan on battens or a stud, taped and skimmed to BS 8000-8. External wall insulation means boards and render over a render carrier, which gives a better U value but changes the look of the building.
The junctions. Reveals, the threshold, the floor junction, the eaves and the party wall are where the heat actually leaves and where condensation appears if they are skipped. Reveals take a thin board or aerogel, joist ends built into a solid wall keep air around them, and a lining that stops short at a party wall leaves a cold strip that grows mould.
Ventilation. A fill or a lining raises the inside surface above the dew point, which is what stops condensation forming, but the moisture still has to leave the house. Trickle vents, a working extract fan in the kitchen and bathroom and air bricks left clear go in with the work. Approved Document F sets the ventilation, BS 5250 covers interstitial moisture, and draughtproofing has the shortest payback of anything here.
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 and building control. Lining a wall inside is not development, which the guidance on insulation confirms, while cladding or rendering the outside falls under what the rules say about cladding a wall. The older part of the village sits inside the Wool Conservation Area, where appearance is controlled, so external wall insulation there is an application rather than an assumption, and Dorset Council keeps the listed entries for the handful of listed buildings in the parish, on which internal work needs consent too. regulation 23 brings a whole wall up to the Part L standard once more than half of it is renovated.
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 mid terrace with two exposed walls, an end of terrace with a full gable and a bungalow with clear access all round are three different jobs. 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. A damp patch that appears only after driving rain almost always means the cavity, and it is worth a look before the next wet spell rather than after it. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
A street of houses built together fails together
Most of Wool went up in a few concentrated bursts, and the biggest of them was the seventies and early eighties. Houses built in the same year to the same detail behave the same way thirty years on, and that is true of the cavity as well as the roof. Where one house in a run has a slumped fill and a damp inner leaf, the neighbours very often have the same thing and have not connected it to the wall.
It cuts both ways. It means a problem here is diagnosable, because we have usually seen the same construction on the same road. It also means a cheap fill sold up and down a street thirty years ago is now a cheap fill failing up and down that street, and the paperwork went with the householders who moved.
The practical advice is simple. Before you spend anything on a wall in this village, find out what is in the cavity. If the answer is nothing, you have a straightforward job. If the answer is old material sitting low and wet, you have a different job, and it starts with taking it out.
Who you are dealing with
A local firm you can check
We cover Wool, East Burton, Bovington and the roads out towards Winfrith, broadly BH20, 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
Wool questions we get asked
How do I find out whether our cavity was ever filled?
One hole in a mortar joint and a borescope. The drill holes from an old fill are often still visible in the pointing too, in a regular grid, once you know what you are looking for.
Is it worth taking an old fill out?
If it has slumped, bridged or got wet, yes, because it is doing harm rather than nothing. If it is still where it was put and dry, leave it alone and spend the money elsewhere.
How long does an extraction and refill take?
Longer than a straight fill, because the old material has to come out through the lowest course and the wall made good before anything new goes in. It is measured in days rather than a morning.
Our terrace only has two outside walls. Is wall insulation worth it?
Less than for an end of terrace, and that is worth saying plainly. On a mid terrace the loft and the draughts usually give you more for the money than the walls do.
Can you match the mortar where the holes are drilled?
Yes, and it is part of the job rather than an extra. On a weathered wall a fresh grey plug in every drill hole is the giveaway of a rushed fill.
Nearby, and next door
Wall insulation near Wool
Wall insulation nearby
Our other trades in Wool
Everything we do in Wareham Wall insulation, all areas Every area we cover
Free quote
Find out what is in your cavity before you spend
Thomas comes out, puts a borescope through one small hole and tells you whether the fill is helping or hurting. The visit and the written quote are free.