Wall insulation in Swanage
Nearly a third of the town predates 1919, so the first question is never which system it is, it is whether there is a cavity there at all.
The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.
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A post-war house in Swanage usually has a cavity that can be filled if a borescope shows it clear and dry, but close to three in ten houses here went up before 1919, and those walls are solid Purbeck stone or nine inch brick with no cavity in them anywhere. Nothing can be pumped into a wall like that. It has to be lined inside or insulated outside, and either way it still has to be able to dry, so the first job here is finding out which wall you have.
Swanage walls give trouble in the old stone front rooms and on filled post-war gables. A front room in an old stone house that never warms up and has black mould behind the wardrobe. And a post-war house on the hill where the cavity was filled years ago and one gable now shows damp patches inside.
We look at the wall before saying a word about systems. Where there is a cavity we drill one small hole and put a borescope in. Where the wall is solid we measure the thickness, tap the plaster and look hard at the floor and window junctions. The site visit and the written itemised quote are free, and insulation in Swanage covers the loft and floors.
The work
Stone, brick and telling a solid wall from a cavity
Solid walls, and why they cannot be filled. Rubble stone and nine inch brick have no gap in them to fill. They stay dry by taking driven rain in and giving it back to the air, so anything fixed to them has to let that carry on. Seal one face and the moisture stops halfway and condenses inside the build up, which is interstitial condensation and it rots joist ends quietly for years.
Internal wall insulation. On a solid Swanage wall this is usually the answer: insulated plasterboard bonded to the masonry, or a batten and stud frame filled with mineral wool and boarded over. On old stone we lean towards wood fibre and a lime skim rather than a foil faced PIR such as Celotex or Kingspan, because a vapour tight board pushes the dew point back into the stone. The vapour control layer gets taped and sealed, which is what BS 8000-8 asks for.
External wall insulation. Boards fixed outside, a render carrier and a silicone or through coloured render over. On a Swanage house it keeps every inch of your room, moves the cold surface outside the masonry and kills the cold bridge at the joist ends in one go. It also changes the look of the building completely, which in a town with this much period frontage is the thing to settle first.
Cavity walls and the borescope. The estates above Swanage town centre are cavity built and most of those walls can be filled. One drilled hole and a borescope shows the width, whether the cavity is clear of mortar snots and whether it is dry. Bonded polystyrene bead flows into awkward cavities and stays put; blown mineral wool behaves well in a clean sheltered one. On a seaward gable bead is the only sensible choice.
Fill that has failed. Wool blown into a Swanage wall decades ago can slump and leave a cold gap across the top of a gable, which shows as a band of black mould on the bedroom wall. A wet cavity, where water is crossing on a bridge, shows as damp patches that come and go with the weather. Both are fixed by extracting the old material first, not by adding more.
The junctions, which are the actual job. Reveals, the threshold, the floor junction, the eaves and the joist ends are where the heat goes and where condensation shows first. Reveals take a thin high performance board, aerogel where there is barely 40mm. A party wall gets a cavity barrier so fill does not travel next door. Miss those and you have a warm wall in a cold frame.
Ventilation, draughts and the numbers. A tighter house needs a route for the moisture in it, so trickle vents, a working extract fan and clear air bricks are part of the work, and Approved Document F sets what is expected. Sealing draughts at the same time is what turns a better u value into a room that actually feels warm, and it is what shifts an EPC rather than the board thickness on its own.
How it runs
Insulating solid stone and cavity walls, step by step
Tell us the age of the house, which wall feels cold, and whether it is rendered, stone or brick. A lot of the town's housing predates the cavity wall, so the first job is finding out what you have. Thomas comes out, uses a borescope through one small drilled hole where there may be a cavity, and prices it himself. Any fill should go in through a registered installer, who normally issues a CIGA certificate, so ask for it.
The quote is itemised: the survey and borescope check, the system and its thickness, making good around windows and doors, sockets and skirting taken off and refitted, ventilation work, and disposal. Internal lining is done room by room, so you can live in the rest of the house, and each room is sheeted and cleared at night. Cavity fill is drilled from outside off a tower or scaffold, and on a terrace the fill stops at your side of the party wall. Damp, a rotten floor joist or a cavity full of rubble means a photograph and a price reach you before we carry on.
Swanage is under Dorset Council. Lining inside and filling a cavity are building control matters, not planning ones. External insulation changes the outside, and inside the Swanage or Herston conservation areas it is not permitted development. On a listed building even internal work can need listed building consent. Where a wall is upgraded, regulation 23 sets the U-value it has to reach under Part L.
Cost
What sets the price of insulating a solid wall
The wall area is the easy part. Every window, door and floor junction is where the time goes, and the heat.
Which wall you have. A clear, dry cavity can be filled quickly. A solid stone or brick wall cannot be filled; it is lined inside or insulated outside, and that is a different job at a different price. A borescope settles it before any quote is written.
Salt, rain and the wrong fill. South west facing walls in the town take driven rain off the sea. A cavity on a very exposed wall can carry water across if it is filled with the wrong material, so the exposure is checked against the wind-driven rain code before we recommend fill.
The junctions. Reveals, the floor junction, the eaves and party walls are where cold bridges and condensation appear if the detail is wrong. That work is slow and is the first thing a cheap quote leaves out.
Getting to it. A stone terrace off the High Street with no rear access, a post-war semi on the hill and a top floor flat in a converted villa each need different access, and work at height rules still set the platform for anything drilled from outside.
Ask others whether they have checked the wall with a borescope, what thickness and system they specify, and how the reveals are detailed.
If damp has appeared
Damp or mould appearing after walls were insulated
Damp patches or mould on an outside wall after cavity fill or an internal lining usually mean rain is crossing the cavity, or warm air is reaching a cold spot at a junction. Ring rather than using the form, especially if it is spreading.
On the first visit we find which it is before anything comes out, because the fix is different: extracting wet fill from a cavity, or sealing and re-lining a reveal. Keep the room aired in the meantime. Scheduled work runs Monday to Friday, 8am to 6pm. When it cannot wait, phone us, and if nobody is free to answer, we return your call as soon as possible.
Worth knowing
Why a Purbeck stone wall has to be allowed to dry
A solid stone wall does not keep water out the way a cavity wall does. It takes rain in, holds it in the outer part of its thickness and gives it back when the weather turns.
That has worked here for two hundred years and it only stops working when somebody seals a face of it. Cement render outside, or a vapour tight board glued inside, traps the water in the middle where it has nowhere to go and the heat loss gets worse rather than better, because wet masonry conducts.
So on the older half of Swanage the question is not how thick, it is how breathable. Wood fibre bedded in lime lets the wall carry on doing what it always did and still lifts the surface temperature enough to stop condensation forming on it. And whatever goes on, it has to run out properly at the edges: line one wall and leave the return, the reveals and the floor junction untouched and you have moved the cold surface rather than removed it. One room done properly beats four done in the middle only.
Who you are dealing with
Who checks your walls before quoting
We are 10 miles away, at 80a Wolverton Road in Boscombe, and insulate walls across Swanage, Herston, Durlston and the Northbrook side, broadly BH19, all under Dorset Council. Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, can be looked up on the public register. Before you book a visit in Swanage, you can read our customers' Google reviews, word for word, on our reviews page.
Thomas Hannen owns the business and comes out to check the wall and price the work himself. A verified customer has given us 10 out of 10 on Checkatrade. Neither the site visit nor the itemised written quote costs you anything.
Planning at a glance
Do you need planning permission in Swanage?
Most repairs in Swanage 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 Swanage |
|---|---|
| Who decides | Dorset Council is the planning authority for Swanage. Dorset Council's heritage pages set out what it controls. |
| Conservation area | Yes: Swanage Conservation Area. Check whether your street is inside the boundary before changing anything visible. |
| Listed buildings | Yes, there are listed buildings in and around Swanage. If yours is one, work can need listed building consent. |
| Protected landscape | Inside the Dorset National Landscape (formerly AONB), so anything visible from outside gets more attention. |
Questions
Questions about wall insulation in Swanage
How do I know whether my Swanage house has a cavity?
Age is a clue and never proof, because render and paint hide everything. A borescope through one small drilled hole settles it in minutes. No honest quote is written before that check.
Can a solid stone wall be filled with anything at all?
No, there is no cavity to fill, and injecting foam into rubble stone traps water in the middle of it. The choice is an insulated lining inside or an insulated render outside.
Does an internal lining cost me much floor space?
It costs you the depth of the build up, roughly a skirting board's thickness on each lined wall. In a small room we use a thinner board and take the reveals in aerogel.
Our cavity was filled years ago and one wall is damp. What now?
Usually the fill has slumped and left a cold gap, or water is crossing at a bridge. We look before removing anything, because the two have different answers.
Does insulating the walls mean I need more ventilation?
Almost always. A tighter house needs a route out for the moisture, so trickle vents, a working extract fan and clear air bricks are part of the job instead of an afterthought.
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Free quote
Find out what your wall is before you insulate it
Thomas comes out, borescopes the cavity or measures the solid wall, and prices the survey, the system and the junctions in writing. The visit and the quote are free.