Cavity Insulation

We supply cavity wall insulation from UK's leading manufacturers such as Kingspan, Celotex, Knauf, Rockwool and many more, in a wide range of sizes and thickness. Products available include insulation slabs, rolls, cavity board, and cavity closers. A third of all heat loss in insulated homes escapes through the walls, so it pays to get the right product for your cavity wall insulation project. 

Try insulation slabs for your cavity wall insulation, they are ideal in flat surfaces needing cover or framing to fill – whether it’s a wall, floor, or roof space. They can be friction fitted for an easier job, and many provide thermal and acoustic insulation properties as well as being water-repellent and non-combustible. Knauf DriTherm Cavity Slabs are a good place to start your search for cavity wall insulation.

Insulation rolls can also be used in all interior insulation requirements, but are particularly useful when you have an uneven background to insulate or pipes and other obstacles in the way. You can also use them to insulate pipes that are liable to freeze. They are effective heat insulation and provide acoustic dampening, but you will need extra fixtures such as insulation supports to keep them from moving position. If you are interested in this type of insulation, then have a look at our Rockwool Insulation Roll and other similar products to compare.

If you’d like to keep the thickness of the insulation down in your build or have partially filled cavity wall space, then a cavity board such as Kingspan Thermawall TW50 is a good option for cavity wall insulation.

If you need some advice before you purchase, feel free to contact us via phone 020 3582 6399 or Live Chat. To read more about Cavity Wall Insulation, see our handy guide.

Knauf DriTherm Cavity Slab 37 - Glass Mineral Wool (All Sizes) 1200mm x 455mm
Knauf DriTherm Cavity Slab 37 - Glass Mineral Wool (All Sizes) 1200mm x 455mm Cavity wall Insulation
Vendor
Knauf
Regular price
from £33.03 £39.64
Sale price
from £33.03 £39.64
Regular price
£0.00
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Rockwool RW3 Acoustic, Thermal, and Fire Performance Insulation Slabs (All Sizes)
Rockwool RW3 Acoustic, Thermal, and Fire Performance Insulation Slabs (All Sizes) Cavity wall Insulation
Vendor
Rockwool
Regular price
from £394.90 £473.88
Sale price
from £394.90 £473.88
Regular price
£0.00
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Celotex CW4000 Cavity Wall Insulation Board 450mm x 1200mm - All Sizes
Celotex CW4000 Cavity Wall Insulation Board 450mm x 1200mm - All Sizes Cavity wall Insulation
Vendor
Celotex
Regular price
from £45.08 £54.10
Sale price
from £45.08 £54.10
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£0.00
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Kingspan Kooltherm K106 90mm x 1.2m x 0.45m (2.16m2)
Kingspan Kooltherm K106 90mm x 1.2m x 0.45m All Insulation
Vendor
Kingspan
Regular price
£82.50 £99.00
Sale price
£82.50 £99.00
Regular price
£0.00
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Kingspan Thermawall TW50 Cavity Wall Board 450mm x 1200mm - All Sizes
Kingspan Thermawall TW50 Cavity Wall Board 450mm x 1200mm - All Sizes Cavity wall Insulation
Vendor
Kingspan
Regular price
from £40.96 £49.15
Sale price
from £40.96 £49.15
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£0.00
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Kingspan Kooltherm K108 Cavity Board (All Sizes) 1200mm x 450mm
Kingspan Kooltherm K108 Cavity Board (All Sizes) 1200mm x 450mm All Insulation
Vendor
Kingspan
Regular price
from £96.50 £115.80
Sale price
from £96.50 £115.80
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£0.00
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Celotex CW4050 50mm x 1.2m x 0.45m - 5.94m2
Celotex CW4050 50mm x 1.2m x 0.45m - 5.94m2 Cavity wall Insulation
Vendor
Celotex
Regular price
£45.08 £54.10
Sale price
£45.08 £54.10
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£0.00
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Knauf DriTherm 32 Mineral Wool Cavity Slabs (455mm x 1200mm) - All Sizes
Knauf Earthwool DriTherm 32 Mineral Wool Cavity Slabs (455mm x 1200mm) - All Sizes Cavity wall Insulation
Vendor
Knauf
Regular price
from £34.90 £41.88
Sale price
from £34.90 £41.88
Regular price
£0.00
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Rockwool RW5 (All Sizes)
Rockwool RW5 1200mm x 600mm (All Sizes) Cavity wall Insulation
Vendor
Rockwool
Regular price
from £691.65 £829.98
Sale price
from £691.65 £829.98
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£0.00
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Celotex CW4075 75mm x 1200mm x 450mm - 4.32m2
Celotex CW4075 75mm x 1200mm x 450mm - 4.32m2 Cavity wall Insulation
Vendor
Celotex
Regular price
£46.59 £55.91
Sale price
£46.59 £55.91
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£0.00
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Actis Hybris 1200mm x 1145mm - All Sizes
Actis Hybris 1200mm x 1145mm - All Sizes All Insulation
Vendor
Actis
Regular price
from £814.40 £977.28
Sale price
from £814.40 £977.28
Regular price
£0.00
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Kingspan Kooltherm K12 Framing Board (All Sizes) - 2.4m x 1.2m
Kingspan Kooltherm K12 Framing Board (All Sizes) - 2.4m x 1.2m All Insulation
Vendor
Kingspan
Regular price
from £252.36 £302.83
Sale price
from £252.36 £302.83
Regular price
£0.00
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Rockwool Full Fill Cavity Batts (All Sizes)
Rockwool Full Fill Cavity Batts (All Sizes) Cavity wall Insulation
Vendor
Rockwool
Regular price
from £600.44 £720.53
Sale price
from £600.44 £720.53
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£0.00
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Celotex CW4100 100mm x 1.2m x 0.45m - 3.24m2
Celotex CW4100 100mm x 1.2m x 0.45m - 3.24m2 Cavity wall Insulation
Vendor
Celotex
Regular price
£46.09 £55.31
Sale price
£46.09 £55.31
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£0.00
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Thermo-Loc 60 min Fire-Rated Check Reveal Cavity Closer 2.4m - All Sizes
Thermo-Loc 60 min Fire-Rated Check Reveal Cavity Closer 2.4m - All Sizes
Vendor
Timloc
Regular price
from £116.40 £139.68
Sale price
from £116.40 £139.68
Regular price
£0.00
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Thermo-Loc 60 min Fire-Rated Cavity Closer 2.4m - All Sizes
Thermo-Loc 60 min Fire-Rated Cavity Closer 2.4m - All Sizes
Vendor
Timloc
Regular price
from £102.07 £122.48
Sale price
from £102.07 £122.48
Regular price
£0.00
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Thermo-Loc 30 min Fire-Rated Cavity Closer 2.4m - All Sizes
Thermo-Loc 30 min Fire-Rated Cavity Closer 2.4m - All Sizes
Vendor
Timloc
Regular price
from £93.48 £112.18
Sale price
from £93.48 £112.18
Regular price
£0.00
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Thermo-Loc Platinum Plus Multi Cavity Closer 2.4m (Pack of 10)
Thermo-Loc Platinum Plus Multi Cavity Closer 2.4m - Pack of 10
Vendor
Timloc
Regular price
£80.35 £96.42
Sale price
£80.35 £96.42
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£0.00
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Thermo-Loc Platinum Plus FX 50mm - 100mm Multi Cavity Closer 2.4m (Pack of 10)
Thermo-Loc Platinum Plus FX 50mm - 100mm Multi Cavity Closer 1.4m - Pack of 10
Vendor
Timloc
Regular price
£96.15 £115.38
Sale price
£96.15 £115.38
Regular price
£0.00
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Thermo-Loc Platinum Plus FX Cavity Closer 2.4m - All Sizes
Thermo-Loc Platinum Plus FX Cavity Closer 2.4m - All Sizes
Vendor
Timloc
Regular price
from £76.40 £91.68
Sale price
from £76.40 £91.68
Regular price
£0.00
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Thermo-Loc Platinum Multi Cavity Closer 2.4m - All Sizes
Thermo-Loc Platinum Multi Cavity Closer 2.4m - All Sizes
Vendor
Timloc
Regular price
from £68.90 £82.68
Sale price
from £68.90 £82.68
Regular price
£0.00
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HControl Hybrid 45mm x 1.6m x 6.25m (Roll size 10m2)
HControl Hybrid 45mm x 1.6m x 6.25m (Roll size 10m2) All Insulation
Vendor
Actis
Regular price
£79.33 £95.20
Sale price
£79.33 £95.20
Regular price
£0.00
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SuperCLOSE XPS Insulated Cavity Closer (20mm - 2.4m) - All Sizes
SuperCLOSE XPS Insulated Cavity Closer (20mm - 2.4m) - All Sizes Cavity wall Insulation
Vendor
Superfoil
Regular price
from £78.95 £94.74
Sale price
from £78.95 £94.74
Regular price
£0.00
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Rockwool Cladding Roll - All Sizes
Rockwool Cladding Roll - All Sizes Cavity wall Insulation
Vendor
Rockwool
Regular price
from £0.00 £0.00
Sale price
from £0.00 £0.00
Regular price
£0.00
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Contract-Closer - All Sizes
Contract-Closer - All Sizes Cavity Closers
Vendor
ARC
Regular price
from £79.95 £95.94
Sale price
from £79.95 £95.94
Regular price
£0.00
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per 
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Recticel Eurowall Cavity Insulation Boards - 1.2m x 0.45m (All Sizes)
Recticel Eurowall Cavity Insulation Boards - 1.2m x 0.45m (All Sizes) Cavity wall Insulation
Vendor
Recticel
Regular price
from £0.00 £0.00
Sale price
from £0.00 £0.00
Regular price
£0.00
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Contract-Closer Single Flange - All Sizes
Contract-Closer Single Flange - All Sizes Cavity Closers
Vendor
ARC
Regular price
£0.00 £0.00
Sale price
£0.00 £0.00
Regular price
£0.00
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Thermaclass Cavity Wall 21 (1190mm x 450mm) - All Sizes
Thermaclass Cavity Wall 21 (1190mm x 450mm) - All Sizes Insulation
Vendor
Celotex
Regular price
from £1,122.22 £1,346.66
Sale price
from £1,122.22 £1,346.66
Regular price
£0.00
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per 
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Smart-Closer Plus - All Sizes
Smart-Closer Plus - All Sizes Cavity Closers
Vendor
ARC
Regular price
from £93.50 £112.20
Sale price
from £93.50 £112.20
Regular price
£0.00
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Thermo-Loc FRSTOP 60 min Fire-Rated Cavity Stop Sock - All Sizes
Thermo-Loc FRSTOP 60 min Fire-Rated 50mm Cavity Stop Sock - All Sizes
Vendor
Timloc
Regular price
from £2.92 £3.50
Sale price
from £2.92 £3.50
Regular price
£0.00
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Isover Batt - CWS 32 (All Sizes) 1.2m x 0.45m
Isover Batt - CWS 32 (1.2m x 0.45m) All Sizes Cavity wall Insulation
Vendor
Isover
Regular price
from £740.36 £888.43
Sale price
from £740.36 £888.43
Regular price
£0.00
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Knauf DriTherm 34 (All Sizes)
Knauf Earthwool DriTherm 34 (All Sizes) Cavity wall Insulation
Vendor
Knauf
Regular price
from £1,135.72 £1,362.86
Sale price
from £1,135.72 £1,362.86
Regular price
£0.00
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per 
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Kingspan Kooltherm Cavity Closers - All Sizes
Kingspan Kooltherm Cavity Closers - All Sizes All Insulation
Vendor
Kingspan
Regular price
from £17.22 £20.66
Sale price
from £17.22 £20.66
Regular price
£0.00
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per 
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Eco-Closer - All Sizes
Eco-Closer - All Sizes Cavity Closers
Vendor
ARC
Regular price
from £112.45 £134.94
Sale price
from £112.45 £134.94
Regular price
£0.00
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Smart-Closer - All Sizes
Smart-Closer - All Sizes Cavity Closers
Vendor
ARC
Regular price
from £74.00 £88.80
Sale price
from £74.00 £88.80
Regular price
£0.00
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Speedline PVCU Ext. XPS. Cavity Closer, 100mm x 2.4m Single Ext (Pack of 10)
Speedline PVCU Ext. XPS. Cavity Closer, 100mm x 2.4m Single Ext Cavity Closers
Vendor
Speedline
Regular price
£83.30 £99.96
Sale price
£83.30 £99.96
Regular price
£0.00
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Thermo-Loc Platinum Plus Cavity Closer 2.4m - All Sizes
Thermo-Loc Platinum Plus Cavity Closer 2.4m - All Sizes
Vendor
Timloc
Regular price
from £69.95 £83.94
Sale price
from £69.95 £83.94
Regular price
£0.00
Unit price
per 
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Thermo-Loc Platinum Plus Check Reveal Multi Cavity Closer 2.4m (Pack of 10)
Thermo-Loc Platinum Plus Check Reveal Multi Cavity Closer 2.4m - Pack of 10
Vendor
Timloc
Regular price
£100.08 £120.10
Sale price
£100.08 £120.10
Regular price
£0.00
Unit price
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Thermo-Loc Platinum Plus FX Check Reveal Multi Cavity Closer 2.4m (Pack of 10)
Thermo-Loc Platinum Plus FX Check Reveal  Multi Cavity Closer 2.4m - Pack of 10
Vendor
Timloc
Regular price
£104.89 £125.87
Sale price
£104.89 £125.87
Regular price
£0.00
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per 
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Thermo-Loc Platinum Plus FX Check Reveal Cavity Closer 2.4m - All Sizes
Thermo-Loc Platinum Plus FX Check Reveal Cavity Closer 2.4m - All Sizes
Vendor
Timloc
Regular price
from £89.75 £107.70
Sale price
from £89.75 £107.70
Regular price
£0.00
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Eco Cavity 0.45m x 1.2m - All Sizes
Eco Cavity 0.45m x 1.2m - All Sizes Cavity wall Insulation
Vendor
Ecotherm
Regular price
from £40.19 £48.23
Sale price
from £40.19 £48.23
Regular price
£0.00
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Ballytherm Cavity 0.45m x 1.2m - All Sizes
Ballytherm Cavity 0.45m x 1.2m - All Sizes Cavity wall Insulation
Vendor
Ballytherm
Regular price
from £58.06 £69.67
Sale price
from £58.06 £69.67
Regular price
£0.00
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Isover Batt - CWS 36 (1.2m x 0.45m) All Sizes
Isover Batt - CWS 36 (1.2m x 0.45m) All Sizes Cavity wall Insulation
Vendor
Isover
Regular price
from £709.14 £850.97
Sale price
from £709.14 £850.97
Regular price
£0.00
Unit price
per 
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Eco-Closer Single Flange - All Sizes
Eco-Closer Single Flange - All Sizes Cavity Closers
Vendor
ARC
Regular price
£0.00 £0.00
Sale price
£0.00 £0.00
Regular price
£0.00
Unit price
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Smart-Closer Plus Single Flange - All Sizes
Smart-Closer Plus Single Flange - All Sizes Cavity Closers
Vendor
ARC
Regular price
£0.00 £0.00
Sale price
£0.00 £0.00
Regular price
£0.00
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Smart-Closer Single Flange - All Sizes
Smart-Closer Single Flange - All Sizes Cavity Closers
Vendor
ARC
Regular price
£0.00 £0.00
Sale price
£0.00 £0.00
Regular price
£0.00
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Celotex CW4085 85mm (Pallet Of 112 Sheets)
Celotex CW4085 85mm Cavity wall Insulation
Vendor
Celotex
Regular price
£906.31 £1,087.57
Sale price
£906.31 £1,087.57
Regular price
£0.00
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Celotex CW4060 60mm
Celotex CW4060 60mm Cavity wall Insulation
Vendor
Celotex
Regular price
£79.12 £94.94
Sale price
£79.12 £94.94
Regular price
£0.00
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Save on your Energy Bills with Cavity Wall Insulation: A guide to cavity wall insulation

What is Cavity Wall Insulation?

Cavity wall consists of two parts, which are separated by a hollow space. These walls are built using masonry materials, such as cinder block or brick. The masonry material is absorbent and can draw humidity or rainwater into the wall.

Compared to solid walls, these walls have better thermal insulation. The empty space between the two walls reduces the transmission of heat into the building from outside. Cavity walls do not allow moisture content from the outer atmosphere to enter the house.

However, while it is very effective to stop cold and hot air coming from the outside, research has shown that 35% of heat loss from UK homes, occurs due to cavity walls. As a result, you have higher energy or power bills. Most homes that were built after the 1930s have cavity walls. The purpose was to keep moisture, humidity, or rainwater from getting in. However, this also led to heat loss between the two walls.

Therefore, it is important to insulate cavity walls to increase power efficiency in your home. This article is a basic but essential guide to cavity wall insulation.

Cavity Wall Insulation Cost

Cavity Wall Insulation

Mineral wool is the insulating material used to insulate cavity walls. The installation involves drilling small holes into outside walls and then blowing the mineral wool into the gap until the cavity is completely filled.

The insulating material that has been injected or sprayed into the cavity traps the air. This also traps warm air and prevent its circulation. Thus, the heat loss is prevented by both conduction and convection.

The mineral wool insulating material is also available in slabs and you can use it to fill a cavity wall – both partially and fully. Phenolic boards and Polyisocyanurate (PIR) are other types of material available to insulate your cavity walls.

Most cavity wall installation companies in the UK provide CIG and CDGC guarantees of 25 years. Remember, the insulation of cavity walls will usually last longer than this.

Types of Insulation Materials

Mineral Wool Fiber
Mineral wool fiber is the most common type of material used for cavity wall batts insulation projects. The material is made from stone, slag, and molten glass. Manufactures melt these compounds, spin them, to produce fibers. The mineral wool insulation material is also available in the form slabs, which are used to partially or fully fill the cavity.

Polyisocyanurate (PIR)

PIR is made from thermoset plastic. This material is often regarded as rigid thermal insulation. You can use PIR boards to partially fill your cavity walls. Experts recommend using an R-value of 5.6 per inch of the foam thickness.

Phenolic

The manufacturing process of phenolic boards involves the formation insulating core by a plastic form between the two tissue face layers. Phenolic boards have fine cell structure and higher closed-cell content, which are used to partially fill a cavity wall.

Pre-Installation Inspection

If your home was built in the last 20 or 30 years, the walls are probably insulated. How to check whether your cavity walls are insulated or not? Hire a registered installer to carry out the process of borescope inspection. The professional drills a small hole in the outside wall and determine if the wall is filled or hollow. You can also check your walls with the local building control department.

For cavity walls batts insulation, your house must meet the following criteria:

  • Your house outside walls is unfilled cavity walls.
  • The cavity is 50 mm wide and there is no rubble.
  • The brickwork and masonry of your outside walls are in good condition.
  • The walls are not exposed to humidity and rain.
  • No risk of flooding.

It is important to carry out a survey in order to check whether the home and outside walls are suitable for the cavity walls insulation. A professional contractor or installer can do this job accurately because they have all the necessary knowledge and tools. After carefully examining the walls using and checking them according to the aforementioned criteria, the installer would be able to insulate your cavity walls using polystyrene beads or mineral wool.

In addition, if your home has uneven or narrow cavities, then, there is a risk of flooding. At the same time, it can be regarded as an exposed site. In this case, the installer will use polyurethane foam to fill the cavity. Remember, this material is more costly than the regular or standard cavity wall insulation material, but it must more effective.

The installer will also check your home’s internal walls for dam patches. If found, the insulation cannot be installed until the problem of damp patches is fixed. You can hire a specialist builder for damp prevention.

If the external walls of your home are joined to another house, then there is a need for inserting a cavity barrier. This way, your neighbors won’t be affected by the insulation. Moreover, if you are living in a flat, the insulation is not possible legally – until everyone living in the building makes an agreement with you to insulate your flat or the whole block. This is usually costly.

How to Insulate a Cavity Wall?

The Cavity insulation of your home’s cavity wall is not a daunting task. You can insulate the cavity wall by injecting the insulating material such as mineral wool into the cavity from outside.

You can do it as a DIY project or hire a contractor to get the job done for you. A professional usually drill holes in the outside walls to inject the insulation material through the holes. After this, the professional will seal the holes with cement. The contractor may use mineral wool or polystyrene beads as insulation material. Some contractors use polyurethane foam.

You need to drill 22mm small holes at intervals of around 1m in the outside wall. Then, blow the insulation material into the cavity. After the insulation material is blown or injected, you need to fill the holes in the brickwork. This way, you will barely notice them.

Experts recommend hiring a professional contractor to do the job – as some think that it can’t be done as a DIY project. A professional installer completes the insulation of cavity walls in 2-3 hours without making any mess.

The cavity closer acts as a seal, preventing external water vapour and damp from entering the cavity wall and the building, whilst also preventing heat from being lost through the gap.

Advantages of Cavity Wall Insulation

The primary advantages of cavity wall insulation are given below:

Heat Loss Reduction: Cavity wall insulation can reduce the amount of heat loss from the wall during winters through convection. The cavity wall insulation is just like putting a lid on a hot cup of tea.

Mold Prevention: Condensation can cause mold and you can prevent it by installing cavity wall insulation. The insulation restricts moisture from passing through the walls. Because the outer wall is porous, water can go through it. When you have cavity insulation installed, it will trap water in between and it will just run above the windows or run down the ground rather than going through the inner wall. Mold will not build up because there is no or lesser moisture.

Lower Energy Bills: with an insulated home, you can save more in power consumption because heat loss is reduced significantly. As a result, the temperature inside your home is warmer and thus, you don’t need to turn the heater on – as they use more power or energy – leading to higher energy bills. 
 

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