Wall insulation in Alderholt
Nothing in the village is listed and there is no conservation area over it, so insulating a solid wall from the outside is genuinely on the table here.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
Most of the villages on this patch are hemmed in by heritage controls that rule external wall insulation out before the technical conversation starts. Alderholt is not one of them. That matters, because on a solid wall the outside route keeps the masonry warm and dry and costs you no floor space at all.
The calls come from two directions. Newer houses on the estates where the cavity is worth checking and sometimes worth filling. And older brick cottages with no cavity at all, where the owner has been told to line the inside and would rather not lose the rooms.
Either way the visit starts with what the wall is. One drilled hole and a borescope shows whether there is a cavity, how wide, whether it is clear, whether it is dry, and whether anything in it has slumped. On a solid wall we measure the thickness, look at the pointing and the render, and find where the floor joists sit. Then you get a written itemised quote with the survey, the system, the junctions and the ventilation on separate lines. Both the visit and the quote are free.
The work
Outside, inside, or into the cavity
External wall insulation. Insulation board mechanically fixed and bonded to the outside face, a render carrier with a reinforcing mesh over it, beads at every edge and reveal, then a through coloured silicone or mineral finish. The masonry ends up on the warm side, so interstitial condensation has nowhere to form and the wall dries outwards. Rooms keep their size, and the work happens outside rather than through your house. Sills, downpipes, the eaves and the meter boxes all have to be dealt with, and that detail is where the time goes.
Internal wall insulation. Where the outside face has to stay as it is, insulated plasterboard bonded and fixed to a flat wall, or PIR board such as Celotex or Kingspan set between battens or a timber stud, then boarded and skimmed. On an old wall that has to stay breathable we use wood fibre and lime instead, so vapour can pass rather than stall behind a vapour tight face.
Cavity fill. On the newer stock, bonded polystyrene bead blown through a drilled pattern, or blown mineral wool where the wall is sheltered and the outer leaf sound. The cavity must be clear, dry and wide enough. The holes are made good in a matched mortar and a house is normally a single day.
Solid walls, which cannot be filled. A nine inch brick wall is not a brick and block cavity wall, however similar they look from the road, and there is nothing inside it to inject. That is the single most common misunderstanding on this kind of work.
Junctions. Window and door reveals, the threshold, the floor junction, the eaves and the joist ends. On external work the insulation has to be returned into every reveal, and where there is no depth for a normal board a thin aerogel goes in instead. Leave one out and you have made a cold bridge, and a thermal bridge is where the dew point lands and black mould appears.
Failed fill. Where an earlier fill has slumped down the cavity, or wetted up because the outer leaf is cracking, it comes out through drilled holes and the wall dries before anything replaces it.
Ventilation. Trickle vents, a working extract in the kitchen and bathroom, and air bricks left clear. Approved Document F sets the expectation. Airtightness without ventilation turns a draughty house into a damp one.
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. There is nothing listed in the village and no conservation area over it, so the ordinary rules apply: insulating inside is not development at all, and cladding or insulating the outside of a house is usually a permitted alteration, which the Planning Portal's external walls guidance sets out. We still check the address rather than assume it. 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. An eighties detached house with a clear cavity, a bungalow with a conservatory in the way, and a solid walled cottage on the street 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. A photograph of the patch and a note of which wall it is on usually tells us more before we arrive than a description does. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
What it means to have no heritage constraint
Nothing here is listed and there is no conservation area over the village. On most of the surrounding parishes at least one of those applies, and it removes an option: you cannot wrap the outside of a listed cottage in insulation, and inside a conservation area a change to the external appearance needs an application and often gets refused.
Where neither applies, external wall insulation becomes a real choice rather than a theoretical one, and on a solid wall it is usually the better engineering. The insulation goes on the cold side, so the masonry stays warm and above the dew point, which is precisely the opposite of what an internal lining does. You keep the floor area, you keep the plaster and the skirtings, and the disruption is outside rather than in the rooms you live in. Heat loss through a solid wall is one of the largest lines on an EPC assessment of a house like this, which is where the payback comes from.
It is not automatic, and we would not pretend otherwise. It changes the look of the house, it needs care at the eaves and the ground line, and on a semi it stops at the boundary unless a neighbour joins in. Roughly a fifth of the homes here predate the cavity wall, so this is a live question in the village rather than an academic one, and it is worth having the conversation properly before defaulting to a lining indoors.
Who you are dealing with
A local firm you can check
We cover Alderholt, Sandleheath, Cranborne and the lanes towards Fordingbridge, broadly SP6, 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
Alderholt questions we get asked
Is external wall insulation allowed on my house?
In this village it usually is, because nothing is listed and there is no conservation area. We check the address rather than assume, and a semi needs a conversation with the neighbour about where it stops.
Which is better on a solid wall, inside or outside?
Outside, on the engineering, because the masonry ends up warm and dry and you keep your floor space. Inside wins where the frontage has to stay as it is or only one room needs doing.
Can a solid brick wall be injected?
No. There is nothing in it to fill. Anyone offering to inject a nine inch wall is selling you something that cannot work.
What happens at the windows on an external system?
The insulation is returned into every reveal, with beads and a proper seal to the frame. Where a reveal has no depth, a thin aerogel board goes in instead of a standard one.
Does wrapping the outside cure a damp wall?
It normally helps a great deal, because the render and the board shed the rain and the masonry behind stays warm. It is not a cure for water coming from the ground or a failed gutter.
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Talk through inside, outside or into the cavity
Thomas comes out, checks what the wall actually is and prices the system, the junctions and the ventilation in writing. The visit and the quote are free.