The thickest product manufactured by Celotex, TB4000 is a high performance, rigid polyisocyanurate (PIR) insulation board with low emissivity foil facings bonded to each side specifically designed to address thermal bridging and reduce heat losses. This product uses a combination of blowing agents with low global warming potential and zero ozone depletion potential (zero ODP).

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Celotex TB4000

TB4000 is available in size 2.4m by 1.2m with thicknesses from 20mm to 40mm and thermal conductivity of just 0.022W/mK. This product is lightweight and easy to cut, handle, and install

It can be used throughout a building project to help maintain continuity of the insulation envelope and is suited to floor, wall, and roof systems. Specific applications include perimeter upstand insulation in ground floors and lining door and window reveals in retrofit projects.

  • Multiple Application Methods.
  • Tapered edge.
  • Can be used to improve the standards of the current building regulations.
  • Keeps energy bills low long term and maximises savings.
  • Creates a more energy efficient environment.
  • Can be applied to extensions, refurbishments, and new build projects.
  • Inbuilt vapour control layer.
  • Great thermal conductivity but thinner board.
  • Long lasting and durable.
  • Helps to meet the requirements of UK thermal building regulations.
  • Thermal conductivity of PIR products does not change over time.

Supplying your home with the correct insulation materials will provide a more energy-efficient and sustainable environment by helping towards the prevention of global warming and climate change. This will also save you money on your energy bills by keeping prevent heat from escaping your property.

The Kingspan packaging should not be considered as protection for the board against weather conditions. The insulation board should be stored on a flat surface in weatherproof conditions preferable inside a building. If the boards should have to be stored outside the correct weatherproofing materials should be provided to protect the products. Boards that have been allowed to get wet should NOT be used.

Celotex PIR Insulation Board TB4000 can be installed in a range of methods. These methods include:

  • Prevents and reduces thermal bridging
  • Timber and steel-framed walls – between the studs.
  • Pitched roofs – between the rafters.
  • Flat roofs – in ventilated cold roof constructions, installed from inside the building.
  • Other retrofit and refurbishment projects – lining existing timber and masonry structures to make them more thermally efficient.

To find out more about Celotex PIR Insulation Board sizes, see our guide below:

Reaction to Fire classification, according to BS EN 13501-1
Achieves a BRE Green Guide rating of A+. Certificate number ENP413
All Celotex products are manufactured under Quality Management Standard – ISO 9001:2015
BBA Approved (Cert no 17/5405, 16/5352)
CE Marked (18. DOPPL4000-01) to BS EN 13165

More Information:
Available in sizes: 20mm, 25mm, 30mm, 40mm
Product Code: TB4000
Thermal Conductivity: 0.022 W/mK
Material: Polyisocyanurate (PIR)
Dimensions: 2.4m x 1.2m

TB4000 Datasheet:

Stocked Thickness20mm25mm30mm40mm
Lambda Value (W/m.K)0.0220.0220.0220.022
R-Value (m2.k/W)0.901.101.351.80
Length (mm)2400240024002400
Width (mm)1200120012001200
Maximum Weight (kg/m2)0.790.951.101.41
Pieces per Pallet120968060

Where can TB4000 be applied to avoid thermal bridging?

This board can be cut using a fine-toothed saw, this is accomplished by measuring the boards to size and making markings if necessary. Then placing the boards on a surface that allows the saw to go all the way through the board. A knife can also be used to score the board, then snapping the board over a straight edge, and then cutting the facing on the other side. Any of cut of the insulation board should be kept in case of gaps within the installed insulation.

Protective clothing is recommended to prevent particles produced from cutting the insulation boards from causing irritation to the eyes or skin. Goggles, face masks, and gloves should be worn to provide protection.

Step 1:

Ensure the timber frame stud has been secured and fixed to the wall. The insulation material fitted into the stud wall should match the depth of the battens and fill each cavity. Ensure the wall is flush with no protrusions. A block can be used to pat insulation into place if necessary.

Step 2:

To install the TB4000 insulation boards, measure the height and width of the new stud wall. Measure and cut the board to size and apply the board over the top of the stud wall using the required fixings. When applying the fixings make sure they are lined up and screwed into timber battens.

Step 3:

Once the wall has been covered with the TB4000 insulation boards, plasterboard can then measure, cut, and installed onto the wall over the insulation boards. The wall can then be decorated with plaster, paint, or wallpaper. Corner bead, scrim tape and finishing products may need to be applied before the decoration stage begins to prevent damage.

How do TB4000 insulation boards prevent thermal bridging?

The TB4000 boards work to avoid thermal bridging as they are a thinner insulation board with a high-quality thermal conductivity of just 0.022W/mK.

The thinner board means it can be installed in areas where thicker insulation boards are not advised.

The space saving board is a great combination with a stud wall as it blocks over all frames and gaps where cold air could come through or cold air could escape – thermal bridging – without reducing too much of the space within the rooms.