Wall insulation in Downton, reveals and all
On the old streets the windows are staying where they are, which makes the reveal around each one the part of the job that decides whether it works.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
On a house with thick old walls and small openings, insulating the middle of the wall is the easy bit. The window reveals are what decide whether you end up with a warm dry room or a warm room with black mould round every frame. In a village where the frontages are protected and the windows are not moving, that detail is the job.
The calls that come from these streets are a cold front room on a terrace, mould round a window in a bedroom, and houses where somebody lined a wall years ago and stopped at the plaster line.
The free site visit covers the wall and the openings together. Reveal depths measured at every window, a borescope through one drilled hole where a cavity is possible, moisture readings at the skirting, and a look at the ground level outside. The written itemised quote then prices the survey, the system and its thickness, each reveal, the ventilation and the making good separately.
The work
Walls, openings and the strip in between
Establishing the wall. Reveal depth and brick bond give the first opinion; the borescope gives the fact. Cavity or solid, how wide, clear or bridged with mortar, dry or a wet cavity, empty or filled and slumped. On the older terraces most walls turn out to be nine inch brick with nothing in them at all.
Cavity fill where there is a cavity. Bonded bead for a narrow, obstructed or weather facing wall; blown mineral wool for a wide, clean, sheltered one. Drilled from outside, blown in, holes pointed to match. One day, and the shortest payback of anything here, with Part L setting what the finished wall should reach.
Solid walls. Nothing to fill, so it is internal wall insulation or external wall insulation. On a protected frontage EWI is usually out, which puts the work inside, and inside is where the reveals start to matter.
The reveal problem. Put 60 or 100mm of lining on the face of a wall and stop at the window, and you have made the reveal the coldest strip in the room. It is also the wettest, because that is where the warm damp air meets it. Yet a lot of these openings have only 30 or 40mm of reveal to play with before you are covering the frame.
How we solve it. A thin high performance board, or an aerogel laminate where there is almost nothing to give, carried right up to the frame and sealed to it. Where the frame is being replaced anyway it can be brought forward instead, which is much the better answer if the timing works. The head of the opening and the sill get the same treatment, because a cold lintel behaves exactly like a cold reveal.
The other junctions. The threshold, the floor junction, the eaves and the joist ends built into the wall are all cold bridge points. The lining runs down behind the skirting and returns onto the party wall, and joist ends in a solid wall get a detail that keeps air round them rather than sealing them in.
Build ups. Insulated plasterboard or PIR such as Celotex or Kingspan on a batten or stud frame with taped joints and a continuous vapour control layer on sound modern walls. Wood fibre in lime on old solid ones, so the dew point lands somewhere that can dry and interstitial condensation has no chance to build. External systems use a mesh basecoat and a render carrier with a finish chosen for the street.
Ventilation, and failures. Trickle vents, extract fans that work, air bricks left clear, to Approved Document F. We also strip linings that are cracking and damp behind, and extract fill that has failed, before anything new goes on.
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.
Wiltshire Council is the planning authority. Downton has its own conservation area and a great many listed entries along the main streets, so anything altering the outside face of a wall is an application, and on a listed building consent covers internal work too under section 7 of the 1990 Act. Internal insulation elsewhere is not development, per the Planning Portal's insulation guidance, and regulation 23 brings building control in once more than half a wall 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 terraced cottage on The Borough, a semi on a post-war estate and a detached house with modern cavity walls are three different jobs with three different reveal problems. 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 mould is round the window rather than out on the wall, say so, because that is a reveal problem and it is usually fixable on its own. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Local
Old openings in protected frontages
There are over a hundred listed entries in this parish and a conservation area over the older streets, and the practical effect on wall insulation is not the one people expect. It is not that you cannot insulate. It is that the windows are staying exactly where they are, in openings that were never designed to have anything added around them.
That turns the reveal into the whole engineering problem. On a modern house you insulate the wall and take a normal board round into the reveal and it is done. On these houses there are often only a few centimetres between the plaster face and the frame, so a standard board would cover the window. The answer is a much thinner, much better performing material in that strip, sealed hard to the frame, and it is worth paying properly for because it is where the condensation and the mould land.
It also changes the sequence. If the windows are due for replacement, do them and the wall together and bring the frames forward into the new lining. If they have just been done, the reveal is what you have and the specification has to work with it. Either way we measure every opening on the survey rather than quoting a wall area, because on these houses that is where the real cost of the job sits.
Who you are dealing with
A local firm you can check
We cover Downton, Charlton All Saints, Redlynch and the villages along the Avon towards Salisbury, broadly SP5, under Wiltshire 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
Downton questions we get asked
My reveals are too shallow for insulation. What now?
A thin high performance board or an aerogel laminate goes in that strip instead of a standard board. It performs like something several times thicker and keeps the frame visible.
Should I replace the windows before or after insulating?
Before, or at the same time, if they are due. The frames can be brought forward into the new lining, which is much the best solution to a shallow reveal.
Why is the mould only around my windows?
Because the reveal is colder than the wall around it, so it is the first surface warm damp air reaches its dew point against. Insulating the reveal and improving the ventilation deals with it.
Can a listed house on the main street be insulated inside?
Often, with consent and the right build up. A breathable, reversible lining in wood fibre and lime is a far easier case to make than rigid foam screwed through historic plaster.
How much does the room shrink?
About 60 to 100mm off each wall that gets lined, depending on thickness. In a small terraced room that is noticeable, which is another reason to do the coldest walls rather than all of them.
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Have the openings measured, not just the wall
Thomas comes out, measures every reveal, works out what the wall is and prices it in writing. The visit and the quote are free.