Wall insulation in Winterborne Kingston
Parts of the village sit in flood zone 3 with the winterbourne a few yards away, and that changes what a ground floor wall should be lined with.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
If water can reach your ground floor, the wall build up has to be one you can dry out and keep, not one you have to rip off and throw away. That single fact decides the material, the fixings and where the lining stops, and it is the part a standard quote never mentions.
People ring about a cold room on the north side, about mould on an outside wall, or because a survey has said the walls are uninsulated and they want to know what can sensibly be done. Where the property sits close to the winterbourne, the answer changes.
The visit sorts out what the wall is: thickness and construction, a borescope through one drilled hole where a cavity is possible, how the render or the pointing is behaving, where the floor joists are built in, and how high water has come in the past. Then a written itemised quote with the survey, the system, the junctions and the ventilation on separate lines. The visit and the quote are free.
The jobs
Cavity fill, linings, and a build up that survives water
The borescope check. One hole and a camera tells you whether there is a cavity, how wide, whether it is clear, and whether it is dry. Around here the last of those matters more than anywhere: a wet cavity does not get filled, and an old fill that has failed and slumped comes out first.
Cavity fill. Bonded polystyrene bead blown through a drilled pattern is the usual answer where the wall is sound, because it bonds and cannot settle, and it does not hold water the way a fibrous material can. Blown mineral wool is a fair choice on a dry, sheltered wall with a good outer leaf. Holes are made good in a matched mortar and a house is normally a single day.
Ground floor linings that can be dried. Where flooding is a real possibility we build the lower part of the wall to recover: closed cell insulation rather than a fibrous quilt, boards on a treated batten or stud with a gap at the floor, no paper faced gypsum low down, and a lime or cement based plaster that can be washed out and dried instead of one that turns to porridge. Sockets are raised where the wiring allows.
Ordinary internal wall insulation. Upstairs, and on any property well clear of the water, the normal build up applies: insulated plasterboard bonded and fixed to a flat wall, or PIR board such as Celotex or Kingspan between battens, boarded and skimmed. On an old solid wall that has to breathe we use wood fibre and lime so vapour can pass.
Solid walls. A nine inch brick wall or a rendered rubble one has no cavity to fill, however similar it looks to a brick and block wall from the pavement. It is internal wall insulation or external wall insulation, and they are different jobs at different prices.
The junctions. Reveals, the threshold, the floor junction, the eaves, the joist ends and any party wall. A shallow reveal takes a thin aerogel board. Leave one out and you have made a cold bridge, and a thermal bridge is where the dew point lands and black mould starts.
Ventilation. Trickle vents, a working extract in the kitchen and bathroom, and air bricks kept clear, which is what Approved Document F expects. After any wetting the ventilation is what actually dries the building, so it matters more here than most places.
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. Lining the inside of a wall is not development and needs no permission, which the Planning Portal confirms, while external wall insulation changes the outer face and is treated differently. There are 7 listed entries in the parish, St Nicholas among them, and listed building consent covers internal work as well as external. Building control is engaged under regulation 23 once a thermal element is renovated, and Part L sets the U value the finished wall has to reach.
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 cottage close to the stream, a post war semi on higher ground and a modern detached house with a wide clear cavity 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 the property has taken water in before, say so when you ring, because that changes what we would put back on the wall as well as what we take off. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
Building a wall you can dry out again
The North Winterbourne runs within yards of parts of the village and the flood maps put ground here in zone 3, with a high surface water rating on top of that. The flood risk service will tell you what applies at a particular address. A winterbourne is seasonal, so the water table climbs through the winter and the ground stays wet for months rather than days.
The mistake, and it is an expensive one, is to insulate a ground floor wall in materials that cannot survive a wetting. Paper faced plasterboard, a fibrous quilt behind it and untreated timber battens will all take water in, hold it and have to be cut out. A house that has been insulated that way is worse off after a flood than one that was never insulated at all, because the drying takes months and the mould gets in behind the board.
Built the other way it is a different story. Closed cell boards, treated battens, a lime or cement based plaster low down, a gap at the floor and raised sockets mean the wall can be washed, dried and kept. It costs a little more at the time and it saves a room afterwards. Where a property has never been near the water we build the ordinary way and put the money into the junctions instead.
Who you are dealing with
A local firm you can check
We cover Winterborne Kingston, the Winterborne villages, Bere Regis and the lanes towards Blandford, 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
Winterborne Kingston questions we get asked
Should I insulate the walls if the house has flooded before?
Yes, but in materials that can be dried and kept. Closed cell board, treated battens and a plaster that will wash out, rather than paper faced gypsum on a fibrous quilt.
Does a high water table stop a cavity being filled?
It can. If the borescope shows the cavity is wet we do not fill it, because a fill in a wet cavity holds the water against the inner leaf instead of letting it drain.
Which fill copes better with a damp wall?
Generally yes here. Bead bonds, cannot settle and does not hold water in the way a fibrous material can if the outer leaf lets driven rain through.
What happens to the electrics when the walls are lined?
Sockets and switches are taken off and refitted through the new lining, and on a ground floor at risk we will suggest raising them where the wiring allows.
How much of the house would you do at once?
As much or as little as you want. The quote itemises each elevation, so treating the cold side first and leaving the rest is perfectly sensible.
Does this affect the energy rating?
Usually, because heat loss through the walls is a large share of the total and the payback is real. We will not put a figure on it, since that turns on how the house is heated.
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Get the walls priced with the water in mind
Thomas comes out, checks the wall and how high water has reached, and prices the build up, the junctions and the ventilation in writing. Both are free.