Wall insulation in Breamore
On a cob or rubble wall the modern sealed lining is the wrong answer, and saying so is most of what a survey here is for.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
Breamore is a village of cob, brick, timber frame and thatch, and on that kind of wall the modern answer is usually the wrong one. A cob or rubble wall has no cavity to fill and it works by getting damp and drying again, so a vapour tight lining on the inside does not just fail to help, it holds water in the wall and does harm.
The calls are a cottage that is cold and expensive to heat, a room that has grown mould in a corner since somebody boarded it, or an owner quoted for cavity fill on a wall with no cavity.
We look at what the wall is made of before anything else: thickness at a reveal, what the plaster is, whether the render is cement or lime, and where the wall gets its water from. The site visit is free and so is the written itemised quote, and if the answer is that your wall should be left as it is, that is what we will write.
The work
Cob, thatch and walls that have to dry
Which wall you actually have. Cob is thick, soft and usually rendered. Rubble and flint with a lime core is thick and irregular. A nine inch brick wall is solid too. None of them has a cavity, so a borescope is only needed on the later houses. On an old one the first job is establishing what is behind the plaster.
Breathable, or nothing. An old solid wall manages moisture by absorbing it and letting it go again from both faces, and any insulation put on it has to allow that. Wood fibre board bedded in lime and finished in lime plaster insulates and still lets the wall dry inwards. Insulated plasterboard with a foil face does the opposite: the masonry behind runs colder and wetter with nowhere for the water to go. BS 5250 sets out how interstitial moisture is managed rather than hoped away.
Where a modern lining does belong. On the later brick houses in the parish, on a wall that stays dry, internal wall insulation in PIR such as Celotex or Kingspan between battens or a stud, or insulated plasterboard on a continuous bed, taped and skimmed to BS 8000-8, is a perfectly good job with a proper vapour control layer behind it.
Cavity walls, where they exist. One small hole in a mortar joint and a borescope gives the cavity width, whether it is clear and dry and whether a failed or slumped fill is in there. A sound cavity takes bonded bead or blown mineral wool from outside, made good in matched mortar. We do not offer a guarantee scheme of our own; a cavity fill is normally installed under an independent one, so ask whoever drills the wall which scheme covers it.
External wall insulation. Boards and a fresh render over a render carrier give the best U value on a solid wall, but on a thatched or listed cottage in the conservation area it is out of the question, and on cob it seals the outside face as well. It belongs on the later houses.
The junctions. Reveals take a thin board or aerogel, which matters more on a cottage where the openings are small and deep. The threshold and floor junction get returned. Joist ends built into a solid wall keep air around them, and under a thatch the eaves detail is about ventilation as much as heat, because the roof space above has to keep moving air.
Ventilation, and what actually helps. On a cottage like this the cheap wins are draughtproofing, secondary glazing where it is allowed, curtains and shutters, a working extract fan and trickle vents so that Approved Document F is still satisfied. Those have a shorter payback and none of the risk, and we would rather quote them than sell you a lining that does harm.
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.
New Forest District 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 village has its own conservation area, so anything that changes the outside is an application rather than an assumption, and there are over sixty listed entries in the parish. On a listed building even a change of plaster can need consent, so that comes before a specification. regulation 23 brings a whole wall up to the Part L standard once more than half of it is renovated, though historic buildings are treated differently.
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 thatched cottage on the street, a farm building converted to a house and a post-war house towards the main road 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. On a cob or rubble wall, tell us if anything has been boarded over recently, because that is usually where the moisture has been trapped. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
Why a vapour tight lining harms a cob wall
A cob wall is earth, straw and lime. It has no damp proof course and it never had one. It stays standing because it takes water in when the weather is wet and gives it back when the weather is dry, and because the render and the plaster on it are soft enough to let that happen. The thatch over it and the plinth under it are both there to keep the worst of the water off.
Put a sealed, foil faced board on the inside of that wall and two things change. The masonry behind the board is now colder, because it is outside the insulation, so it holds more water for longer. And the inside face, which was half of its drying, is closed. The moisture goes somewhere: up the wall, into the timbers, or out through the render, taking the face with it in the first hard frost.
None of that means a cob cottage has to stay cold. It means the materials have to match the wall. Wood fibre in lime, lime plaster, generous draughtproofing, a well insulated roof and ventilation that works. That is a real job with a real result, and it is a different job from the one a national installer will offer you.
Who you are dealing with
A local firm you can check
We cover Breamore, Upper Street, Woodgreen and the lanes along the Avon, broadly SP6, under New Forest District 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
Breamore questions we get asked
Can a cob cottage be insulated at all?
Yes, with materials that let it breathe. Wood fibre bedded and finished in lime is the usual route. What it cannot take is a sealed board that stops the wall drying inwards.
Somebody has quoted us for cavity fill. Is that possible here?
Not on a cob, rubble or nine inch brick wall, because there is no cavity to fill. That is worth checking before anyone drills anything, and it takes a tape at a window reveal to settle.
Our thatched cottage is cold. What helps most for the money?
Usually draughtproofing, the roof space where there is one, and stopping anything letting water into the wall. All three have a shorter payback than a lining on a building like this.
Is lime plaster really necessary?
On a wall that has to dry, yes. Cement render and gypsum plaster both hold water against soft masonry, and on cob that is how you lose the face of a wall.
Will we need consent for work inside a listed cottage?
Often, yes, because internal finishes are covered as well as the outside. It is worth asking before anyone quotes, and it is why we put the question in writing rather than guessing.
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Have an old wall looked at before anything covers it
Thomas comes out, works out what the wall is made of and what it can safely take, then prices it in writing. The visit and the quote are free.