Wall insulation in West Lulworth
In a house that is shut up for weeks at a time, a warmer wall only works if a little heat and some moving air come with it.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
A house that is only lived in part of the year behaves differently from one that is lived in every day, and there are a lot of those in West Lulworth. Insulate the walls of a building that then stands cold and shut up for weeks and you can make the mould worse rather than better, because insulation without heat and without air moving is only half a measure.
The calls here are a holiday let with black mould turning up between visits, a cottage on the seaward side with a cold, damp inside face, and owners wanting to know whether a solid stone wall can be insulated at all.
We look at the wall, the heating and the ventilation as one thing, because on a house used this way they cannot be separated. The site visit is free and so is the written itemised quote, and where the answer is background heat and a fan rather than a lining, we will say that.
The work
Walls, heat and air in a house that stands empty
What the wall is. Stone rubble, nine inch brick and later brick and block cavity all sit in this village. Thickness at a reveal and the bond usually settle it, and where they do not, one hole in a mortar joint and a borescope gives the cavity width, whether it is clear and dry, whether the ties are bridged and whether a failed or slumped fill is in there already.
Cavity fill. A sound, dry cavity takes bonded bead or blown mineral wool from outside, drilled in a pattern and made good in matched mortar. This close to open water a bead that sheds water tends to be the safer choice than a wool. We do not offer a guarantee scheme of our own; a cavity fill is normally installed under an independent one, so ask whoever drills your wall which scheme covers it.
Solid stone and brick. Nothing to fill, so internal wall insulation on the inside face: insulated plasterboard on a continuous adhesive bed, or PIR such as Celotex or Kingspan between battens or a stud, taped and skimmed to BS 8000-8. On an old rubble wall that has to keep drying, a vapour open build up goes on instead of a foil faced board. External wall insulation behind a render carrier gives the better U value and is a planning matter in the conservation area.
Heating that never fully stops. On a property that stands empty, a low background temperature does more for the fabric than any amount of insulation added on its own. Insulation makes that background heat cheap to hold, which is the real argument for doing it here. A cold, sealed, unheated house is the reliable recipe for condensation on the coldest surface in it.
Ventilation that runs while nobody is there. Trickle vents left open, a humidity controlled extract fan in the bathroom and kitchen, and air bricks kept clear rather than boarded over. Approved Document F sets the ventilation and BS 5250 covers the interstitial moisture a sealed wall can trap. This is the half of the work that gets left off a quote and it is the half that decides whether the mould comes back.
The junctions. Reveals take a thin board or aerogel. The threshold and floor junction get returned rather than stopped short, joist ends built into a solid wall keep air around them, and a lining that stops dead at a party wall leaves a cold strip. In a house that is not heated continuously, those cold bridges are exactly where the water goes first.
The outer leaf. Salt keeps a wall damp between showers, so open joints, cracked render and blown pebbledash let penetrating damp through before insulation is even in the argument. Repointing or patching the exposed elevation is often the better first spend, and it costs less than a lining.
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 and building control. Lining a wall inside is not development, which the guidance on insulation confirms, while cladding or rendering the outside is covered by what the rules say about cladding a wall. The village has its own conservation area, so external wall insulation here is an application rather than an assumption, and Dorset Council keeps the listed entries for the forty odd listed entries in the parish, on which internal lining needs consent too. regulation 23 brings a whole wall up to the Part L standard once more than half of it 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 stone cottage on the village street, a house on the hill taking the full weather off the sea and a converted outbuilding used as a let are three different jobs. 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 property is a let, tell us when it is empty, because that is when a wall is worth looking at and when the work is least disruptive. The phone is answered 24 hours for emergencies; scheduled work runs Monday to Friday, 8am to 6pm.
Worth knowing
An empty house is a cold house, and cold walls collect water
Condensation is not about how much moisture is in the air so much as how cold the coldest surface is. Warm air holds water; cool it against a cold wall and it lets that water go. In a house that is lived in, heating and everyday air movement keep surfaces above the dew point most of the time. In a house shut up for three weeks in February, every surface drops to the temperature of the wall.
That is why a let or a second home grows mould in corners, behind wardrobes and on the north gable while the house next door does not. It is also why insulating those walls genuinely helps, but only as part of the same decision as keeping a little heat on and leaving the air moving. Insulation raises the surface temperature. Heat keeps it there. Ventilation takes the moisture away. Take any one out and the other two do not finish the job.
The practical version is unglamorous: line or fill the walls where the wall justifies it, set a low background temperature on a thermostat rather than switching everything off, fit humidity controlled extract, and leave the trickle vents open when you lock up.
Who you are dealing with
A local firm you can check
We cover West Lulworth, Lulworth Cove, East Lulworth and the roads towards Wool, broadly BH20, 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
West Lulworth questions we get asked
Will insulating the walls stop mould in an empty property?
It helps a great deal, because the wall surface runs warmer. On its own it is not enough. A little background heat and ventilation that runs while nobody is there do the rest.
Should we turn the heating off between lettings?
Off entirely is the worst option for the building. A low background setting costs less than putting right the decoration, and it keeps the surfaces above the point where they collect water.
Can a solid stone wall be insulated?
Yes, on the inside, with a build up that lets the wall keep drying. A sealed foil faced board on rubble stone traps moisture in the masonry and moves the problem rather than curing it.
Is cavity fill sensible this close to the sea?
On a sheltered elevation usually yes, with a bead that sheds water. On a wall taking the full weather it may be better left clear and lined inside instead.
How long will the work take in a holiday let?
A cavity fill is a day. A lining is measured in rooms and includes the making good, so we plan it around a gap in the bookings rather than promising to work round guests.
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Get the wall, the heat and the air looked at together
Thomas comes out, sees where the cold surfaces are and prices the wall, the ventilation and the making good in writing. Both are free.