Insulation Services Bournemouth

Loft, rafter, warm roof and wall insulation across Bournemouth, Poole and Christchurch. Start here, work out which one your house actually needs, then go straight to the detail on it.

Get your free quote 07435 839745

Insulation

Which Insulation Does Your House Actually Need?

For a roof, Approved Document L sets a target U-value of 0.16 W/(m²·K) when a thermal element is renovated, and its own worked example for a cold loft is 250 mm of mineral fibre. That is the number to hold in your head. Everything else, the product, the depth and the build-up, follows from the loft itself and from whether you want to use the space.

Bournemouth Roofing & Building provide professional insulation services across Bournemouth, Poole, and Christchurch. We specialise in loft insulation, wall insulation, and energy-efficient upgrades for residential and commercial properties. Our experienced team installs high-quality insulation materials designed to improve energy efficiency, reduce heat loss, and lower energy bills. Whether you're upgrading an existing property or improving insulation as part of a renovation, we offer the same team from first visit to last, an itemised written price, and work throughout the Bournemouth, Poole, and Christchurch area.

Heat rises, and in most houses the roof is the easiest place to stop it leaving. Getting the loft right is usually the most straightforward energy upgrade there is.

We install loft and roof insulation for homeowners, landlords and property managers across Dorset. That covers a simple top-up over the joists in an empty loft, a thin reflective system where space is tight, and full rigid board build-ups for loft conversions and warm roofs. Because we are roofers as well, we look at the roof covering, the eaves and the ventilation at the same time rather than just filling the space and leaving.

  • Cold loft insulation between and over the joists
  • Rafter-level and warm roof build-ups for conversions
  • Eaves ventilation kept clear as part of the job
Request a free quote See our roofing work

The site visit is free and so is the written itemised quote. Thomas Hannen prices every job himself.

Loft conversion with foil-faced insulation boards between the rafters, mineral wool and a Velux window
Loft, room-in-roof or warm roof Different jobs, different materials. We match it to the space.

What we install

TLX, Eco Roll & Celotex Loft Insulation Systems

There is no single best insulation. There is the one that suits your loft, the space you have, and what you plan to do with the room.

TLX Insulation

We install TLX insulation systems to improve thermal efficiency in loft spaces without significantly reducing head height. TLX is a multi-layer reflective insulation solution that helps retain heat while also improving breathability, making it ideal for both upgrades and renovation projects.

It is the one to use when depth is the problem: sloping ceilings, rooms in the roof, dormers, and upgrades where a thick layer of board or wool would eat into the room.

Eco Roll Insulation

A cost-effective and high-performance mineral wool solution. Installed between and over joists, it helps reduce heat loss and improve energy efficiency, making your home warmer and lowering energy bills.

The second layer runs across the joists to cover the cold bridge the timber creates. It goes down quickly, but it needs depth to work, so it is not the answer where head height matters.

Celotex Insulation

We install Celotex rigid insulation boards for lofts requiring high thermal performance in a compact thickness. Celotex is ideal for loft conversions or upgrading existing insulation, offering excellent energy efficiency and a durable, long-lasting solution.

It is also the usual choice for sloping ceilings and warm roof build-ups. Cut and fitted tight, taped and sealed, with the ventilation gap kept clear above it where the detail calls for one.

Rigid Celotex insulation boards cut and fitted between roof rafters in a loft

Choosing between them

Choosing Between Loft, Rafter & Warm Roof Insulation

Every insulation choice is a compromise between how much heat you keep in, how much space you give up, and what you spend. Here is how the three sit against each other.

If the loft is empty and you just want it warmer

Eco Roll mineral wool over the joists. It is the cheapest thermal gain you can buy, and in an unused loft the depth costs you nothing because nobody is standing up in there. If the loft is already insulated but thinly, adding a cross layer over the top is normally worth doing. Depths, cross layers, boarding over the top and keeping the eaves open are all set out in full on our loft insulation page.

If head height is the constraint

TLX. On a sloping ceiling or a room in the roof, every extra millimetre of build-up comes straight off the room. A thin multi-layer system gets you a meaningful improvement without closing the space in, which is why it suits upgrades to rooms that are already finished.

If the loft is becoming a room

Celotex or another rigid PIR board. When you are converting, the insulation has to fit between and under the rafters, hold its shape, take a plasterboard finish and perform within a fixed depth. Rigid board does all of that. The same applies if the roof is being stripped and rebuilt as a warm roof, with the insulation above the structure.

If the roof is already done and the rooms are still cold

Then the heat is leaving through the walls, and that is a different survey with a different set of materials. Cavity fill, a lining on the inside face or an insulated render on the outside all depend on what is already inside the wall, so it gets drilled in a mortar joint and looked at before anyone names a system. That side of the work has its own page: wall insulation, including the walls we would tell you not to touch.

One thing that applies to all three: boarding a loft out for storage straight on top of insulation squashes it flat and undoes a good part of what you paid for. If you want storage, tell us at the survey and we will raise the floor over the insulation instead.

Two regulatory points are worth knowing, because they change what a job has to include. Under the Building Regulations, regulation 23 says that renovating more than 50% of a thermal element's surface area means the whole element has to be brought up to standard, so far as that is technically, functionally and economically feasible. For a roof, Approved Document L gives that standard as 0.16 W/(m²·K), with 250 mm of mineral fibre as the worked example for a cold loft. In practice that is why a re-roof and a loft upgrade so often want doing together.

The second point is ventilation. Insulating a loft floor makes the space above it colder, which makes it easier for moisture rising out of the house to condense up there, so the eaves airflow matters more after the job than it did before. Approved Document F covers the ventilation side, and it is the reason we fit vent trays and keep the eaves clear rather than stuffing insulation tight into them.

The survey is what decides the system, whether the loft has never been touched or already has a thin layer down. We fit insulation for homes in Ferndown and properties around Verwood as well as across Bournemouth itself.

How it works

Our Loft Insulation Installation Process

Most lofts are a day or two of work. The survey is what decides whether it goes smoothly.

Survey the loft

We get up there and look at the joists, the existing insulation, the eaves, the ventilation and any signs of damp or a leak.

Agree the spec

We tell you which system suits the space and why, cover any head height or storage implications, then quote it in writing.

Prepare

Loft cleared enough to work in, existing material dealt with, eaves opened up and vent trays fitted where the airflow needs protecting.

Install and tidy

Insulation fitted tight with no gaps, hatch and services left accessible, waste taken away and the loft left clean.

Because the roof and the loft are the same job to us, insulation often gets done alongside a repair or a re-roof. If you are already booked in with our roofers in Poole or having roof work done in Christchurch, it is worth doing the loft while the access is there.

A word on numbers. Insulation performance depends on the specific product, the depth installed and the construction it goes into, so we quote the exact specification for your loft after the survey rather than putting generic figures on a web page.

What it costs

What Drives the Cost of Insulating a House

Insulation at loft-floor level is one of the cheapest jobs on this website. Anything at rafter level is several times the price of it. That single difference, whether the insulation goes across the floor of a cold loft or against the slope of the roof, does more to the number than the brand on the packaging ever will.

We quote the exact specification after the survey rather than putting a generic figure on a web page, because the depth, the product and the build-up all depend on the loft. Here is what is behind the price.

What moves the number

  • Floor level or rafter level. Rolling mineral wool between and over the joists of an empty loft is quick, needs no lining and gives up no room. Insulating at rafter level means cutting board to fit, sealing it, keeping a ventilation gap above it, and usually boarding and skimming afterwards. It is a different trade sequence, not just a different material.
  • What is already up there. A loft that has never been touched is straightforward. A thin, old, compacted layer that has to be lifted, bagged and taken away adds labour and disposal before the new material goes down.
  • Access and clearance. A small hatch on a landing, a boarded loft full of belongings, or a boarded floor that has to come up first all add time. Tell us at the survey and we can include clearing and moving items rather than discovering it on the day.
  • Whether you want storage. Boarding straight onto insulation squashes it and throws away a good part of the performance you paid for. Raising the floor over the insulation on a proper deck costs more, and it is the only version that works.
  • Ventilation work. Vent trays or eaves guards, opening up blocked eaves, and sealing the routes moist air uses, such as the hatch, pipe penetrations and downlighters, are part of doing it properly.
  • Regulations, if a thermal element is being renovated. Where more than 50% of a roof is being renovated, regulation 23 brings the whole element into scope at the Approved Document L target of 0.16 W/(m²·K). That is a scope change, and scope changes are what move quotes.
  • Head height, on a room in the roof. Every extra millimetre of build-up on a slope comes straight off the room, so the choice of system is often driven by the depth you can spare rather than by cost. That is the usual reason a thin multi-layer system is specified instead of thick board.
  • VAT. The installation of qualifying energy-saving materials in residential accommodation is currently zero-rated for VAT in Great Britain, under HMRC VAT Notice 708/6, for supplies made up to 31 March 2027, after which the relief reverts to the reduced rate of 5%. Conditions apply and HMRC's guidance is the authority, not us, but it is a genuine and time-limited effect on what you pay.
The three loft systems compared on the things that decide which one we specify.
System Mineral wool (Eco Roll) Multi-layer reflective (TLX) Rigid PIR board (Celotex)
Where it goes Between and over the joists, at loft-floor level Against the slope, on sloping ceilings and rooms in the roof Between and under rafters, or above the structure on a warm roof
Best when The loft is empty and you just want the house warmer Head height is the constraint and the room is already finished The loft is becoming a room, or the roof is being rebuilt
Depth Approved Document L's worked example for a cold loft is 250 mm of mineral fibre Thin by design, which is the whole reason to use it Set by the rafter depth and the target U-value for the build-up
Cost to the room None. It sits below the space The least of the three at rafter level The most, because the board plus the lining is the thickest build-up
Relative cost The cheapest thermal gain available Higher per square metre, lower than losing the room Highest, and it is doing a structural and finishing job as well
Watch out for Boarding over it flattens it and throws the performance away Detailing at the laps and edges is what makes it work The ventilation gap above it has to be kept clear

About the 270 mm figure

You will see 270 mm quoted almost everywhere as the loft insulation depth. It is worth knowing that the number does not come from the regulations. The string does not appear anywhere in Approved Document L, in either the current edition or the 2021 one. What Approved Document L actually gives is a target U-value of 0.16 W/(m²·K) for a renovated roof, and 250 mm of mineral fibre as a worked example of reaching it. Depth is a means to a U-value, not a standard in itself, and the depth you need depends on the material.

What we will ask you

Whether the loft is empty, part boarded or fully boarded. What is up there now and roughly how deep it looks against the joists. Whether you want to store things up there afterwards. Whether there are downlighters in the ceiling below, and whether there is a water tank or a junction box that has to stay accessible. Whether the roof itself is due any work, because doing both at once saves a visit and sometimes a scaffold.

Why two insulation quotes differ

Usually because one has priced the ventilation and the other has not. Vent trays, opening up blocked eaves and sealing the hatch are the parts that stop a well-insulated loft turning into a damp one, and they are the easiest parts to leave out of a cheap quote. After that it is depth, whether the existing material is being lifted and taken away, and whether a proper raised deck is included if you want storage.

We survey the loft before we quote, and we say so in writing. If we find a leak or existing damp up there we will tell you and deal with that first, because insulating over a wet roof only hides it. The specification, the depth and the ventilation work are all itemised so you can see what is included.

Questions

Insulation Questions, Answered

Which insulation is right for my loft?

It comes down to what the loft is for. If it is an empty loft you only use for storage, Eco Roll mineral wool laid between and over the joists is the cheapest way to cut heat loss, and it is what most houses want. If you need to keep head height, or you are working in a tight space where a thick layer will not fit, TLX multi-layer reflective insulation does more in less depth. If the loft is being converted into a room, or the roof is being stripped and rebuilt as a warm roof, rigid Celotex PIR board is the one that suits. We look at the loft before recommending anything.

Will insulating cost me head height?

At joist level, no, because the insulation sits below the floor of the loft and does not touch the space above it. At rafter level it always costs you something, because whatever you fit is taking up part of the depth between the rafters and whatever you line it with adds a bit more. That is the main reason people choose TLX for a room in the roof: it is a thin multi-layer system, so it gives away less of the room than a thick rigid board would. If head height is tight, tell us at the survey and we will work the build-up around it.

Do I need ventilation with loft insulation?

Yes, and it is the part people get wrong. A cold loft works because air moves through it and carries away moisture that rises out of the house. Insulate the loft floor and the loft above gets colder, which makes it easier for that moisture to condense, so the ventilation at the eaves matters more than it did before. Insulation stuffed tight into the eaves blocks that airflow. We keep the eaves clear, fit vent trays or eaves guards where they are needed, and check any existing roof or soffit vents while we are up there.

Can you insulate a room-in-roof or dormer?

Yes. Rooms in the roof, dormers, sloping ceilings and the little triangular voids behind the knee walls are all worth doing, and they are usually where an older converted loft is losing most of its heat. It is more involved than rolling insulation across a loft floor because every surface has to be treated and the airflow above the insulation has to be kept clear. We normally use a rigid board or a multi-layer system on the slopes, depending on the depth available and how much of the room you can afford to lose.

What about condensation and damp?

Insulation on its own does not cause damp, but a badly detailed installation can move condensation somewhere it was not before. Warm, moist air from the house has to be kept out of the cold roof space, and the roof space has to be able to breathe. That means blocking the obvious routes for moist air such as gaps around loft hatches, pipes and downlighters, keeping the eaves ventilation clear, and getting the vapour control layer on the warm side when we insulate at rafter level. If we find an existing leak or damp when we survey, we will tell you and deal with that first. Insulating over a wet roof just hides it.

Do you clear the loft first?

We need the loft empty to work in it, so it is easiest if you can move belongings out beforehand. If that is not practical, tell us when we quote and we can include clearing and moving items to one side, and we will tell you what needs to go somewhere else entirely. We will also flag anything we cannot cover, such as recessed downlighters, and anything that needs to stay accessible, such as a water tank or electrical junction box.

Where we work

Insulation Work Across Dorset

We serve these areas for loft insulation, wall insulation and thermal upgrades:

Loft insulation is normally permitted development and does not need planning permission, though external wall insulation changes the appearance of the building and can, particularly on a listed building or in a conservation area. The Planning Portal guidance on insulation sets out where the line falls, and we will flag it at the survey if we think it applies to you.

Every area we cover

Insulation by location

Insulation in every town and village we cover

Each page is written from the ground, the housing stock and the planning position of that settlement, using Environment Agency, British Geological Survey, Valuation Office Agency and Census records. 84 pages covering 115 settlements.

Within 8 miles

8 to 14 miles

14 to 20 miles

Free quote

Get an Insulation Quote in Bournemouth

We will survey the loft, tell you which system suits it and why, and put a clear written quote in front of you. No obligation.

Request a free quote Call 07435 839745