Wall insulation in Ashley Heath, and the wall that takes the rain
On an exposed elevation what goes into the cavity decides whether driving rain stops at the outer leaf or crosses to the inside.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
Houses at Ashley Heath sit on open, exposed ground and the elevation that gets the weather faces south west. On a wall that takes driven rain year after year, what you put in the cavity matters more than how much of it you put in, because the wrong material carries water across the gap to the inner leaf instead of stopping it.
The calls reflect that. A damp patch that appears on one wall after a wet, windy week and dries back in a settled spell. A bungalow with a cold end that never comes up to temperature. Or a house filled years ago where nobody is sure what went into the wall or whether it is still there.
We read the wall before saying anything about systems. One small hole and a borescope shows the cavity width, whether it is clear and dry and what is in it already, and on the weather side that last point is the one that decides the job. The site visit and the written itemised quote are both free.
The work
What goes into a cavity that faces the weather
The borescope, and what we look for. Cavity width, mortar snots bridging the ties, whether existing fill has slumped, and whether the material in there is wet. On the south west elevation we check at more than one height, because a bridge low down and a slump high up produce completely different symptoms inside.
Bead rather than wool on the exposed side. Bonded polystyrene bead is loose beads stuck to each other with adhesive. Water cannot travel through it the way it travels through a wet mat of mineral wool, and it stays where it is put instead of settling. Blown mineral wool is the older method and it is still fine on a sheltered elevation. How exposed a wall is to wind driven rain is a measured thing, assessed against BS 8104 rather than guessed.
Filling a suitable wall. Where the cavity is clear, dry and wide enough, the wall is drilled on a pattern, filled and made good in a day on a normal bungalow. The holes are made good in mortar matched to the wall, and on a single storey the whole run is worked off a tower rather than a scaffold.
When the answer is no. A cavity that is bridged, already wet or too narrow does not get filled, and we would rather tell you that on the visit than take the work. On solid brick and block the route is internal wall insulation, IWI, with insulated plasterboard or a batten and stud frame filled with mineral wool, PIR laminate such as Celotex or Kingspan where depth is tight, and the vapour control layer taped per BS 8000-8.
External wall insulation, EWI. Boards, a render carrier and a render finish. On an exposed elevation it does something a cavity fill cannot: it puts a weatherproof coat over the masonry, so the driving rain never reaches the brick at all. It keeps the room size too. What it changes is the appearance of the house and the eaves detail.
Fill that has failed. Wool that has slumped leaves a cold band under the eaves and black mould inside along that line. A wet cavity gives penetrating damp that follows the weather. Both begin with extraction, drilling out and vacuuming the old material, and on the weather side the refill is normally bead.
Junctions, ventilation and draughts. Reveals, the threshold, the floor junction, the eaves and the joist ends carry the heat loss, and a thermal bridge left at any of them collects condensation whatever the u value beside it. Reveals take a thin board or aerogel. Then trickle vents, a working extract fan and clear air bricks, because airtightness without ventilation is how a warm house turns damp, and Approved Document F sets what is expected.
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.
Ashley Heath is under Dorset Council. There is no conservation area over the settlement and a single listed entry, so this is a building control question rather than a planning one, and even an external system is largely your own choice of appearance; Planning Portal guidance on external walls covers where permission does bite. Where an existing wall is upgraded, regulation 23 sets what it has to reach under Part L.
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 detached bungalow on a wide open plot, a two storey house with a full gable to the south west and a chalet with rooms in the roof are three different jobs before a hole 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. We are around eight miles away and over on the Ringwood side regularly, so an address here is normally looked at within a day or two. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
How rain gets across a filled cavity
A cavity wall works because there is a gap. Rain soaks into the outer leaf, reaches the back of it, and drips down the inside face of that leaf with nothing to carry it further. Fill the gap with the wrong material on an exposed elevation and you have given the water a path. Mineral wool that has become saturated, or wool packed tight against a wall tie loaded with mortar, will pass moisture to the inner leaf, and what shows up inside is a damp patch that appears after driving rain and fades in a dry week.
That is why the material choice here is not a preference. On the south west face at Ashley Heath we specify bonded bead, which does not wick, and we check the outer leaf before anything goes in: open joints, cracking in the render, a blown patch or a bridged tie all have to be dealt with first. Insulating a wall that is letting water in simply moves the problem to the inside face, and it is the single most common reason a cavity fill gets blamed for damp it did not cause.
Who you are dealing with
A local firm you can check
We cover Ashley Heath, Horton Road, St Leonards and the Ringwood side, broadly BH24, 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
Ashley Heath questions we get asked
Why does one wall go damp only after windy rain?
That pattern is water crossing the cavity rather than condensation. Something is bridging the gap, or the fill on that elevation is holding water instead of shedding it.
Is bead really better on an exposed wall?
On the weather side, yes. Bonded bead does not wick moisture across and it holds its position rather than settling, which is the failure that shows up under the eaves.
Should the outer brickwork be repaired before filling?
Always. Open joints, cracking and blown render let water in, and filling a wall in that state moves the problem to the inner face instead of solving it.
How long does a fill take on a bungalow out here?
A day for a normal bungalow, worked from outside off a tower, with the drill holes made good in matching mortar. Access on these plots is usually straightforward.
Can I have an insulated render instead?
Yes, and on an exposed elevation it has a real advantage, because it keeps driving rain off the brickwork entirely. It changes the look of the house, which is the trade off.
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Get the weather side checked before anything is blown in
Thomas comes out, reads the cavity, looks at the outer leaf and prices the work in writing. The visit and the quote are free.