Intermediate Floor data sheet

We recommend a suspended timber approach to Intermediate floors, making use of i-joists requires much less timber and creates less on-site waste. End Seals should be fixed to the ends of the joists and mortar bedded all around the joist to form an airtight seal.

Technical information

STEICO joists fulfil the demands from house builders for greater clear spans and better dimensional stability, whilst not increasing the size of the cross section of the construction elements.

Carefully follow manufacturer's designed layout ensuring all instructions and special considerations are followed. Ensure that any holes drilled within the web of the joists are done so within the stated limits set out by the manufacturer. Ensure no holes or notches are placed within the flanges of the joists.

Where joists terminate within a masonry wall, Simpson End Seals (SES) are fixed to the ends of the joists and mortar is bedded all around the joist to form an airtight seal eliminating the need for mastic seals. Perimeter noggins should be fixed between the joists.

Egger Peel Clean Xtra 22mm chipboard flooring affixed with Egger D4 adhesive should be used to form the floor deck. By eliminating the use of nails the strength of the board is increased, whilst squeaks associated with mechanical fixings are minimised. Once installed and sealed, the deck remains watertight for 42 days giving a working platform to use whilst the external walls and roof are installed. Once work is complete, the covering can be peeled off and a clean and unspoilt floor is achieved. Ceiling should be created using 15mm plasterboard screw fixed to the underside of the floor joists.

Due to the relatively thin web section of 8mm and the 600mm centering, STEICO joists reduce both the thermal and acoustic bridge that traditional timber joists suffer from. Therefore in single dwelling situations, insulation within the floor void is not required in order to meet both Part L and Part E of the Building Regulation, saving costs on both insulants and labours.

Ensure that where joists run parallel with solid walls and the span is greater than 3m there is a restraint strap fixed to that wall and across a minimum of 3 joists with timber blocking between the joists. Other than this, there is no requirement for mid span block.


How to install

This animation illustrates the Travis Perkins plc recommended installation of an intermediate floor with a good balance between cost of the solution and thermal efficiency, using traditional building materials.

The construction has been thermally modelled by the BRE and accredited by LABC and delivers a 101% overall improvement against SAP Appendix K.

Watch video



Hints & Tips

When using Egger D4 Adhesive carefully read and adhere to the instructions on the packaging and wear suitable protective clothing especially gloves.

When installing the STEICO joists, safety bracing should be fixed to the top of the joists every 2.5m. The bracing can be removed as the floor deck is being installed.

By using STEICO joists, continous spans can be installed over internal walls improving the structual stability of the floor.

Due to the large web section of the STEICO joists, holes can be created large enough to allow soil pipes to pass through, removing the requirement for trimmers and making it easier to install whole house ventilation systems.

Contact the floor design team during the design stage to maximise the performance of the product and reduce building costs.