Wall insulation in Bere Regis
A lot of the older walls here already carry a hard cement render, and lining the inside of one shuts the wall in from both sides at once.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
A wall has to be able to dry somewhere. Where an old solid wall has been rendered in hard cement at some point in the last fifty years, it has already lost most of its ability to dry outwards. Seal the inside face as well, with a foil backed board and a vapour barrier, and there is nowhere left for the moisture to go at all.
That is behind a lot of the calls from the village. A room that feels cold and smells damp. Salting and blown plaster low down on an outside wall. Somebody quoted for insulated boards on a cottage where the render is already the problem.
So we look at the render as carefully as the wall. Whether it is cement or lime, whether it is cracking or has blown away from the background, where the water is getting behind it, and how the wall is drying now. On the newer houses a borescope through one drilled hole answers the cavity question instead. Then a written itemised quote with the survey, the system, the junctions and the ventilation on separate lines. The visit and the quote are both free.
The jobs here
Getting a wall to dry before insulating it
The render comes first. Where hard cement render is cracked or has blown, water gets in behind it and cannot get out. No lining should go on the inside of that wall until the render is dealt with, because you would be sealing water into the masonry. Sometimes that means patching, sometimes taking it off and replacing it with a lime render that lets the wall breathe.
Breathable internal wall insulation. On a solid wall the safe build up is vapour open: wood fibre board bedded in lime, finished in lime plaster, no plastic sheet in it. Moisture can move through and leave. It is the right answer on a rubble, cob or soft brick wall and it is not slower to live with, only slower to build.
Where a rigid board is fine. Insulated plasterboard, or PIR board such as Celotex or Kingspan on battens or a timber stud, on a dry, hard, modern wall. It is thinner for the same performance and quicker to fit. On the wrong wall it is the thing that causes interstitial condensation behind the board.
Solid walls cannot be filled. A nine inch brick wall, or a rubble wall under render, has nothing inside it to inject, whatever it looks like next to a brick and block cavity house on the same street.
Cavity fill on the newer houses. Bonded polystyrene bead blown through a drilled pattern, or blown mineral wool on a sheltered wall with a sound outer leaf. Clear, dry and wide enough or it does not get filled. A wet cavity, a bridged one, or a fill that has already failed and slumped is a different conversation.
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 any of them out and you have built a cold bridge, and a thermal bridge is where the dew point lands and black mould appears.
Ventilation. Trickle vents, a working extract in the kitchen and bathroom, and air bricks kept clear. Approved Document F sets the expectation, and on a wall that is already struggling to dry, the ventilation is doing half the work.
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 a wall on the inside 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 43 listed entries in the parish, St John the Baptist among them, and listed building consent reaches internal work as well as external. Building control comes in 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 rendered cottage on the street, a brick house behind it and a modern estate house with a clear cavity are three different jobs before anything is opened up. 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. Tell us whether the render outside that wall is sound, because on an older house that is usually where the answer is. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
A wall sealed on both faces has nowhere to go
Think of an old solid wall as something that is always slightly wet and always drying. Driven rain, and the prevailing weather here comes from the south west, wets the outside. Cooking, washing and breathing put moisture into the inside. Both faces let it out again, and the wall stays in balance.
Hard cement render closes the outside face. It is strong, it does not move with the wall, and it cracks, so water gets in at the cracks and then cannot evaporate through the render the way it would through lime. Plenty of walls in the village have been in that state for decades and are coping, because they are still drying inwards into heated rooms.
Now line the inside with a sealed board. The heat no longer reaches the masonry, so the wall is colder and holds more water, and the last escape route has just been closed. What follows is salting and blown plaster at the bottom of the wall, damp behind the boards, and rot in any joist end built into it. It is why we look at the render before we quote a lining, and why on these houses the answer is often to repair the outside first, insulate breathably, and get the ventilation right at the same time.
Who you are dealing with
A local firm you can check
We cover Bere Regis, Winterborne Kingston, Wool and the lanes towards Wareham, 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
Bere Regis questions we get asked
Our cottage is cement rendered. Can we still insulate inside?
Yes, once the render is sound and in a breathable build up. What we would not do is put a sealed board on the inside of a wall that is already shut in on the outside.
How do I tell lime render from cement render?
Cement is hard, uniform and tends to crack in straight lines and sound hollow where it has parted. Lime is softer and more forgiving. We can usually tell by tapping the wall.
Does the render have to come off before you start?
Not always. Sound render stays, cracked render gets repaired, and render that has blown away from the wall behind it needs taking off. We tap the whole elevation at the survey.
Why is the plaster blowing at the bottom of the wall?
Usually salts brought through by water that cannot escape. It is a symptom of a wall that is not drying, and lining over it without fixing that makes it worse.
Is there a real saving in doing the walls?
It normally does, because heat loss through solid walls is a big share of the total and the payback is real. We will not attach a number to it, since that turns on how the house is heated.
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Get the render and the wall looked at together
Thomas comes out, checks how the wall is drying now and prices the repair, the lining and the ventilation in writing. The visit and the quote are free.