Wall insulation in Beacon Hill
Plenty of the newer houses here were built with boards in the wall and a clear gap in front of them, and that gap is there for a reason.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
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A house built since the war usually has a cavity wall, but before anything is blown in, a borescope has to show whether it is empty, dry and clear. A house built from the 1980s on was often built with insulation already in the cavity. Boards or batts fixed against the inner leaf leave a clear gap in front of them on purpose. Blowing that gap full is not a top up, it is closing a drainage channel somebody designed in, and it is how a dry wall becomes a damp one.
Beacon Hill walls raise a question on newer and older houses alike. A newer house whose owner has been told the walls are uninsulated and doubts it. And an older house with a wall that runs cold, or a bedroom with mould in the corner.
Either way we open the Beacon Hill wall and look. One small drilled hole and a borescope shows whether there is anything against the inner leaf, how wide the remaining gap is and whether it is clean and dry. The site visit and the written itemised quote are both free.
The work
Reading a cavity that may already have boards in it
Part filled, full filled and empty. Three different walls that look identical from the garden. An empty cavity can usually be filled. A full filled cavity, blown at some point in the past, needs checking rather than topping up. A part filled cavity, built with rigid boards against the inner leaf, was designed with a residual gap and generally should be left alone.
Why the gap is there. In a part filled Beacon Hill wall the boards keep the heat in and the clear space in front of them lets any water that gets through the outer leaf run down and out at the base. Fill it and you have bridged the cavity along its whole height. That is the mechanism behind most of the damp that gets blamed on cavity insulation, and it is entirely avoidable.
Cavity fill where it does suit. On the older Beacon Hill houses, where the borescope shows a clear, dry cavity of a usable width, a registered installer drills it on a pattern, fills it and makes it good in a day. Bonded polystyrene bead flows around the ties and stays put; blown mineral wool is the older method and it still performs in a clean sheltered cavity.
Internal wall insulation, IWI. For solid brick and block, or a cavity too narrow to fill, the lining goes inside: insulated plasterboard bonded to the masonry, or a batten and stud frame filled with mineral wool. PIR laminate such as Celotex or Kingspan reaches the target in the least depth, with the vapour control layer taped so warm air cannot get behind it, per BS 8000-8.
External wall insulation, EWI. Boards, a render carrier and a render finish over the elevation. It keeps the room size, warms the masonry through and deals with the joist ends. With nothing listed and no conservation area here, the appearance is genuinely your own decision, which is not true in most of the villages around this one.
Fill that has failed. Wool blown into a Beacon Hill wall decades ago settles and leaves a cold band under the eaves, showing inside as black mould along the top of a wall. A wet cavity where water bridges gives damp patches that come and go with the weather. Both begin with extraction, drilling and vacuuming the old material out.
Junctions, ventilation and draughts. On a Beacon Hill house, reveals, the threshold, the floor junction and the joist ends are where the heat loss concentrates, and a thermal bridge left at any of them gathers 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 makes a warm house mouldy, and Approved Document F sets what is expected.
How it runs
Cavity fill, lining or external boards, and how each goes
Before anything else, Thomas works out what kind of wall you have. He looks at how the bricks are laid, measures the wall's thickness at a window reveal and, where there is a cavity, drills one small hole to look inside with a borescope for existing fill, rubble or damp.
That survey is the first line of the written quote. The rest lists the insulation system with its thickness, the work round windows and doors, any extra ventilation, and taking the waste away.
A cavity fill is drilled and injected from outside and the holes filled to match the mortar; ask whoever installs it for proof of registration and a CIGA certificate. Internal lining goes room by room, with furniture moved and sheeted and the room left usable at the end of the day. Offcuts and waste leave with us. If a wall turns out wetter than expected, or the wall ties are corroded, the photo and the price come to you first, before we go on.
Dorset Council is the authority here. With nothing listed and no conservation area over Beacon Hill, external insulation is an ordinary permitted development question, and Planning Portal guidance on external walls sets out the limits. Wall insulation is notifiable building work, and regulation 23 sets what an upgraded wall must reach under Part L.
Cost
Reveals, junctions and the wall you actually have
We will not quote wall insulation per square metre. Covering the plain stretches of wall is fast; the edges round every window, door and floor are where the labour is.
What kind of wall. An empty cavity in good condition can usually be injected in a single day. Solid masonry has no cavity to fill, so it is either lined on the inside or boarded and rendered outside, a bigger job at a different price. A cavity that went up with partial fill boards usually has no room left for more.
Reaching the wall. Injection happens outside. Low eaves can be reached from a tower, while a gable two floors up needs scaffolding under the work at height rules. Lining from inside needs no platform, but you lose the use of each room while it is being done.
Wind and rain. Gables facing open fields take the heaviest driving rain, and some are simply not suitable for cavity fill because water can track across it. We judge exposure before recommending anything.
Where heat leaks. Reveals, the junction with the floor, the eaves and any wall shared with next door are the cold spots. Boarding outside means extending sills and moving pipes; lining inside means refitting sockets, skirtings and radiators.
Ask anyone else quoting whether a borescope has actually been put into your wall, what product and thickness they propose, how the reveals get finished, whether ventilation is included, and who makes good the plaster and paint.
If damp has appeared
Damp or mould that appeared after the walls were insulated
Damp or black mould on an outside wall that was dry before it was filled or lined is most likely down to the fill or a cold junction. Rain may be tracking through the insulation across the cavity, or warm room air may be meeting a cold junction and condensing there.
They are fixed differently, so we find out which before anything is removed. Phone rather than use the form, and note where the damp is, how high it reaches and whether it comes with rain or with cold snaps. The first visit pins down the cause and makes any wet electrics or loose plaster safe. Scheduled work runs Monday to Friday, 8am to 6pm. If it cannot wait, phone, and if we cannot pick up, we call back when we can.
Worth knowing
A wall built with insulation in it is a different job
Part filled cavity construction became normal in this country during the 1980s and 1990s, and it is why a great many perfectly good modern walls should never be pumped. The builder fixed rigid boards to the inner leaf and deliberately kept a clear residual gap in front of them, usually around 50mm.
That gap is not wasted space. It is the drainage route for anything that gets through the brickwork, and the cavity trays and weep holes at the base exist to let it out.
You cannot see any of that from outside, and a survey that judges a house by its age will get it wrong in both directions. So the check is the whole job here: drill once, look, and find out whether you are looking at boards and a gap, a clean empty cavity or something that was blown twenty years ago. If it turns out your walls are already part filled, the honest answer is that the wall is largely done and the money is better spent on the loft, the draughts and the ventilation. That answer means nothing gets drilled, and it is still the right one.
Who you are dealing with
Wall insulation towards Organford and Lytchett Minster
We are 9.8 miles from Beacon Hill, based in Boscombe, and we insulate walls here and in Lytchett Minster, Organford and the Sturminster Marshall side of BH16, and on towards Wareham. Planning and building control questions go to Dorset Council.
The firm is Bournemouth Roofing & Building Ltd, which is registered in England and Wales with company number 15471719. It is owned by Thomas Hannen, and he checks the wall and prices the work himself. On Checkatrade, one verified customer has given us 10 out of 10. We charge nothing for the site visit, and nothing for the written, itemised quote. Before you book a visit in Beacon Hill, you can read our customers' Google reviews, word for word, on our reviews page.
Planning at a glance
Do you need planning permission in Beacon Hill?
Most repairs in Beacon Hill 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 Beacon Hill |
|---|---|
| Who decides | Dorset Council is the planning authority for Beacon Hill. Dorset Council's heritage pages set out what it controls. |
| Conservation area | None covers Beacon Hill, so a like-for-like repair is ordinary maintenance. |
| Listed buildings | Nothing in Beacon Hill is on the statutory list, so listed building consent does not come into it. |
| Protected landscape | No National Park or National Landscape covers Beacon Hill. |
Questions
Questions about wall insulation in Beacon Hill
How do I know if my cavity is already part filled?
One drilled hole and a borescope. You can see the board against the inner leaf and measure the gap in front of it, which is the difference between a fillable wall and one to leave alone.
What happens if a part filled cavity gets pumped anyway?
You bridge the drainage gap from top to bottom, so water that used to run out at the base now reaches the inner leaf. That is the classic cause of damp blamed on cavity insulation.
My house is from the 1990s. Do I need anything doing to the walls?
Often not: if the boards are there and the gap is clear, the wall is largely done and your money goes further on the loft, the draughts and the ventilation.
How long does a cavity fill take where it is suitable?
A day for a normal house with clear access, drilled and filled from outside, with the holes made good in mortar matched to the wall.
Can I have insulated render here without permission?
There is no conservation area and nothing listed at Beacon Hill, so the appearance is your own choice. It is still worth checking the permitted development position for your own house.
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Find out whether your wall needs anything at all
Thomas comes out, borescopes the cavity, tells you straight if it is already done and prices anything that is worth doing. The visit and the quote are free.