Cavity Insulation

Cavity Wall Insulation & Mineral Wool Insulation

Rose Building Supplies supplies cavity wall insulation for suitable masonry cavity wall construction, with a strong range of Knauf DriTherm mineral wool cavity slabs, alongside Knauf OmniFit thermal and acoustic mineral wool slabs and selected Mannok PIR cavity insulation boards.

Our range includes insulation in several thicknesses for different cavity widths, wall types and thermal requirements. The correct product depends on the construction build-up, insulation specification and intended application.

Knauf DriTherm Cavity Insulation Slabs

Knauf DriTherm cavity slabs are glass mineral wool insulation products designed specifically for suitable masonry cavity wall systems.

Our range includes DriTherm 37 and DriTherm 32 Ultimate cavity slabs in different thicknesses, including 50mm, 85mm, 100mm, 125mm and 150mm, subject to stock availability.

The semi-rigid slabs are designed to fit closely within the cavity, helping create a continuous insulation layer when installed correctly.

DriTherm 37 vs DriTherm 32

The main difference is thermal conductivity. DriTherm 32 has a lower thermal conductivity than DriTherm 37, meaning it can provide greater thermal resistance at the same thickness.

The correct product depends on the cavity width and required thermal performance, so check the project specification rather than choosing by thickness alone.

What Thickness of Cavity Insulation Do You Need?

The required thickness depends on the cavity width and the complete wall build-up.

Common mineral wool thicknesses in our range include 50mm, 85mm, 100mm, 125mm and 150mm. The correct size should match the wall design and the specified insulation system.

Where a target U-value has been specified, follow the approved construction details and thermal calculations.

Full-Fill Cavity Insulation

Many mineral wool cavity insulation products are designed for full-fill cavity wall systems, where the insulation fills the cavity in accordance with the product specification and approved wall construction.

Always follow the manufacturer guidance and project drawings, particularly where exposure conditions or wall design affect the suitability of the system.

Knauf OmniFit Thermal & Sound Insulation Slabs

Our insulation range also includes Knauf OmniFit Thermal & Sound Insulation Slabs in 50mm and 100mm thicknesses.

Unlike DriTherm cavity slabs, OmniFit is a multi-application glass mineral wool insulation designed to provide both thermal and acoustic performance.

OmniFit slabs can be used in suitable applications including internal floors, internal walls and partitions, pitched roofs at rafter level and timber-frame walls.

If your project specifically requires insulation for an external masonry cavity wall, check whether a dedicated cavity product such as Knauf DriTherm is specified. OmniFit should be selected according to its approved application and project requirements.

Mannok PIR Cavity Insulation

Alongside mineral wool insulation, we also stock selected Mannok PIR cavity insulation boards.

PIR cavity boards provide high thermal performance from a relatively slim rigid board and can be used in suitable full-fill or partial-fill cavity wall systems, depending on the product.

These products are a useful alternative where the wall design specifically calls for rigid PIR insulation rather than mineral wool.

Mineral Wool vs PIR Cavity Insulation

Mineral wool cavity slabs are semi-rigid and can fit closely around minor irregularities in masonry. They are widely used in full-fill cavity wall systems.

PIR cavity insulation boards are rigid and provide low thermal conductivity, making them useful where strong thermal performance is required within a limited thickness.

The right choice depends on the wall specification, cavity width and required thermal performance.

Understanding Thermal Conductivity

Thermal conductivity, often shown as a lambda value in W/mK, indicates how readily heat passes through the insulation material.

A lower thermal conductivity generally means greater thermal resistance at the same thickness. However, overall wall performance depends on the full wall construction rather than the insulation alone.

Cavity Insulation for Extensions & New Builds

Cavity insulation is commonly required for extensions, new homes and other masonry construction projects.

Depending on the project, you may also need cavity closers, wall ties, lintels, bricks, blocks, DPC and other building materials.

If you are working from architectural drawings or a building specification, check the required insulation type and thickness before ordering.

Cavity Insulation in Peterborough & Huntingdon

Cavity insulation is available for collection from our Peterborough and Huntingdon branches, subject to stock availability.

Our Peterborough branch in Fengate supplies cavity insulation to builders, contractors and homeowners across Peterborough and surrounding areas. Our Huntingdon branch serves customers across Huntingdon and nearby parts of Cambridgeshire.

Local delivery is available for many cavity insulation products, which can be particularly useful when ordering multiple packs for extensions and larger projects.

Cavity Insulation Delivery to Corby

Rose Building Supplies also provides cavity insulation delivery to the Corby area. Corby is a delivery-only service area and does not have a Rose Building Supplies branch or collection point.

Need Help Choosing Cavity Insulation?

If you are unsure which insulation you need, check your drawings or specification for the required product type, cavity width, thickness and application.

Our team can help you identify suitable products from our range when you provide those details.