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Guide To Celotex Floor Insulation

Celotex PIR insulation is a multi-purpose board that can be used for various applications. It’s commonly used as floor insulation and can be used on a variety of floors to provide effective thermal insulation. This guide will outline the types of floors that Celotex insulation can be installed in, and why it is a good choice for each floor type.

What makes Celotex so appealing for floor projects is that it comes in 16 different thicknesses, from 20mm to 150mm. This means that you can find the perfect level of insulation for your specific needs. Celotex is also an extremely effective insulator, with a thermal conductivity of 0.022 W/mK.

There are three main types of floors that Celotex insulation can be installed in – concrete floors, beam and block floors, and suspended timber floors.

Concrete Floors

Celotex insulation is an effective way to reduce heat loss through concrete floors. The thermal insulation properties of the Celotex board stop the heat from escaping through the floor, keeping the room at a comfortable temperature. This is especially important in rooms that are below ground level, as they are more prone to heat loss.

If you are thinking about installing insulation on a concrete floor, you’ll need to lay a layer of damp-proof membrane (DPM) first. This will protect the Celotex board from moisture and dampness. Once the membrane is in place, you can lay the Celotex insulation on top. The 100mm Celotex GA4100 is the most popular thickness for insulating a concrete floor.

The joints must be tightly butted together to prevent any air leakage or condensation. You can use an aluminium foil tape to seal the joints and prevent thermal bridging.

Beam and Block Floors

Beam and block floors are a type of suspended floor that consists of concrete beams that support a blockwork infill. This is a common type of floor construction in the UK.

The space between the beams is typically filled with Celotex insulation, as this provides an effective thermal barrier. Celotex insulation is easy to install in beam and block floors. The boards simply need to be cut to size and fitted snugly between the beams. Once in place, the joints can be sealed with a vapour layer control (VCL) to prevent any air leakage.

Suspended Timber Floors

Suspended timber floors are a type of floor construction that is becoming increasingly popular. They are made up of timber joists that are supported by metal hangers or wooden beams.

Celotex PIR insulation is well suited to this type of flooring as it is lightweight and easy to install. The insulation can be cut to size and installed on the underside of the joists, or between the joist and the beam or hanger.

Celotex is a good choice for suspended timber floors as it helps to reduce noise transmission between floors and more importantly provides excellent thermal insulation. It also helps to protect the timber from moisture and rotting, which can be a common problem with timber floors.


In conclusion, Celotex insulation is a versatile and effective product that can be used in a variety of floor types. It is a good choice for concrete floors, beam and block floors, and suspended timber floors as it helps to reduce heat loss and noise transmission. It is also an effective way to protect the floor from moisture and rotting.

Our customer service team can advise on which Celotex insulation would be suitable for your project. We also sell other PIR insulation from EcoTherm, Recticel, and Kingspan, which are almost identical to Celotex in terms of performance and manufacture.

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