Wall insulation in Merley
Most walls on this estate were filled within a few years of each other, so the question is what condition that old material is actually in.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
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Almost every Merley house has a cavity wall, and a borescope shows whether the old fill is still dry and in place or has to come out. About half of this estate went up between 1973 and 1982, and houses built together were often filled around the same time, so much of that fill is now decades old. The useful question here is not whether to insulate a wall but what condition the last lot of material is in.
The symptoms in Merley follow from that. A bedroom that has turned cold along the top of an outside wall. Damp patches on the weather side that were never there before. Or a house being sold, where a survey has flagged the cavity and nobody has actually looked inside it.
We look with a borescope through one small hole drilled in a mortar joint, take moisture readings on the inside face and walk round each elevation. Then a free written itemised quote, with the survey, any extraction, the system, the junctions and the making good on separate lines. For the loft, see insulation in Merley.
The work
Fill that has done thirty years, and what comes next
Reading the existing fill comes first. The scope shows what is in the cavity, how far down it sits, whether it is dry and whether it is still packed against the inner leaf. On stock of this age the usual faults are material that has slumped and left a void at the head of the wall, and material that has been wetting for years and stopped working long ago.
Slumped fill. Blown fibre in a Merley wall settles under its own weight, particularly where it was installed thinly or where the wall has been knocked about by later work. The result is a warm band low down and a cold one along the top, which is why one wall of a bedroom feels different from floor to ceiling. It shows on a cold morning as a stripe of condensation before it ever shows on a meter.
Wet cavity, and extraction. Where water is crossing on the fill, penetrating damp appears inside on the weather face, black mould follows behind furniture, and no amount of internal decoration fixes it. The material has to come out. Extraction is done through drilled holes with a vacuum, the cavity is checked clear, the outer leaf is repaired and repointed where it needs it, and only then does anything new go back.
Refilling, and what with. A clear, dry Merley cavity of decent width takes bonded polystyrene bead, which flows into corners, holds its position and does not wick water across the way an older fibre could. Blown mineral wool is still a reasonable answer on a sheltered wall. Fill goes in from outside through a pattern of drilled holes made good in matching mortar, and a normal house is a day.
Internal and external work. IWI is the fallback for a wall we will not refill: insulated plasterboard bonded on, or batten and stud with mineral wool or PIR between, boarded and skimmed, with Celotex, Kingspan or an aerogel board depending on the depth you can spare. Reveals, threshold, floor junction and joist ends get wrapped, because that is where the heat loss is. EWI puts board on the outside face with a render carrier and a thin coat, and takes out the thermal bridge at eaves and corners in one pass.
Ventilation. Insulating a wall shifts the dew point and takes away the draughts that were drying a Merley house out, so trickle vents, a working extract fan and any air brick that has been blocked up belong in the same quote. A taped, continuous vapour control layer keeps interstitial condensation out of the build up. An EPC will move on the back of it, though the payback you feel is the airtightness.
How it runs
Checking the cavity, then insulating the right way
Thomas surveys the walls and prices the job himself. Most houses in Merley were built in the seventies and early eighties with cavity walls, and some were filled later, so the first job is a borescope through a small drilled hole to see whether the cavity is empty, filled and dry, or filled and wet. The quote lists that survey, the system and its thickness, making good round windows and doors, any ventilation work, and disposal.
Cavity fill is drilled from outside by a separate specialist installer, off the ground or a tower, which on a bungalow is quick; internal lining is done room by room, with furniture moved, floors sheeted, and each room left usable at night. Holes are filled to match the mortar, and every offcut of plasterboard leaves with us. If we find wet or slumped fill, missing wall ties or damp at a junction, we send a photo and a cost and wait for your answer.
Lining the inside of a wall needs no application, as Planning Portal guidance on insulation confirms; for the outside face, read Planning Portal guidance on external walls. The register of listed buildings BCP Council holds puts Merley's entries on and around the Canford School estate. It is notifiable work: regulation 23 means a renovated thermal element must meet Approved Document L, and building control look at the U-value and the ventilation together.
Cost
Filled, empty or wet: why the cavity decides the cost
Wall area is the easy part to measure, so we don't price wall insulation by the square metre. What is in the cavity. An empty, clean cavity is filled quickly with blown bead or mineral wool. Fill put in years ago that has got wet on the weather side has to be extracted before anything new goes in, and that is slow work.
Which way you go. Where the cavity can't be filled, the choice is lining inside with insulated plasterboard, which takes a little off each room, or external wall insulation with render over it, which needs a scaffold and changes the look.
Junctions. Window and door reveals, the floor junction and the eaves are where cold bridges and condensation show up. Getting those right is most of the labour on internal lining.
Access. A bungalow can be drilled from the ground; a two storey gable needs a tower. The work at height rules set that platform.
Making good. Sockets, radiators and skirting come off and go back on with internal lining, and then there is the skim and decoration.
Ask other quotes whether the cavity has actually been checked with a borescope, what system and thickness is specified, how the reveals are detailed, and who makes good afterwards.
If damp has appeared
Damp patches after the walls were filled
Damp patches or mould on the inside of an outside wall after cavity fill or lining usually mean rain is tracking across wet fill, or warm air is meeting a cold spot at a reveal or floor junction.
Note which wall it is on and whether it shows after wind-driven rain, keep the room aired, and wipe mould off with a mild solution rather than painting over it. Ring us; the form is slower. We look before taking anything out, because the fix depends on which of those it is. Scheduled work runs Monday to Friday, 8am to 6pm. If the line goes unanswered, we ring back at the first chance.
Worth knowing
A whole estate whose walls were filled at the same time
Three quarters of the housing here dates from between the war and the early eighties, and the peak of it is the 1970s. That has an odd consequence. Houses built together were often filled in the same era too, with the materials of the day, so many of those fills are now decades old.
So when one fails it is rarely a one off. Neighbours compare notes about cold bedrooms and damp corners within a year or two of each other, and a likely reason is that the fills went in around the same time and have aged at a similar rate.
The practical value of knowing that is what it saves you. If a house two doors down has had its cavity extracted and the material came out wet, that is a real reason to have yours scoped rather than assume. And if the fill in yours is dry, packed and sitting where it should, we will tell you that too and leave it alone. Extraction and refill is a proper job with real disruption, and it is not something to do on the strength of the year the estate was built.
Who you are dealing with
Wall insulation around Oakley and the Willett Road
Merley lies 6.6 miles north west of our Boscombe base. We cover it with Oakley, the Willett Road side and the BH21 addresses around them, and planning and building control sit with Bournemouth, Christchurch and Poole Council.
The company is Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719. It belongs to Thomas Hannen, who drills the test hole, looks down the borescope and prices the work himself. You can see a verified customer's 10 out of 10 on Checkatrade. There is no charge for the visit or the written itemised quote. Before you book a visit in Merley, you can read our customers' Google reviews, word for word, on our reviews page.
Planning at a glance
Do you need planning permission in Merley?
Most repairs in Merley need no application at all. What decides whether a change to the outside of your house does is who the council is, whether a conservation area or a listing applies, and whether the place sits in a protected landscape.
| Question | In Merley |
|---|---|
| Who decides | BCP Council is the planning authority for Merley. BCP Council's heritage pages set out what it controls. |
| Conservation area | The Merley estates are outside any conservation area, but Oakley Lane and Canford Magna conservation areas sit on its edge, so check your address. |
| Listed buildings | Yes, there are listed buildings in and around Merley. If yours is one, work can need listed building consent. |
| Protected landscape | No National Park or National Landscape covers Merley. |
Questions
Questions about wall insulation in Merley
How do I know whether my old cavity fill has slumped?
A cold band along the top of an outside wall, or condensation showing as a stripe on a cold morning. The borescope confirms it by looking at where the material actually sits.
What does extracting cavity fill involve?
Holes drilled through the outer leaf and the material vacuumed out, then the cavity checked clear. It is dusty outside rather than in, and the holes are made good afterwards.
Can the cavity be refilled straight after extraction?
Only once it is dry and the outer leaf has been repaired. Putting new material into the same wet wall repeats the fault with a fresh invoice attached.
Is old fill always worth taking out?
No, plenty of it is dry, packed and doing its job. We take it out when it has slumped or been wetting, and we say so plainly when it has not.
Is clearing and refilling a cavity one visit or two?
Two, normally: a day to extract the old material and check the gap is clear, then the refill once the wall has dried, with the drying time set by readings rather than a diary.
Nearby, and next door
Wall insulation near Merley
Nearby places we also cover for wall insulation, with straight-line distances from Merley, and the other trades we offer in Merley itself.
Wall insulation nearby
Our other trades in Merley
Wall insulation guides
Damp at the bottom of a wall: what it is PIR board vs mineral wool: which insulation? Hollow-sounding wall: blown plaster or dot and dabEverything we do in Broadstone Wall insulation, all areas Every area we cover
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Find out what your cavity is holding
Thomas comes out, scopes the wall, tells you whether the old fill is still working and prices the answer in writing. The visit and the quote are free.