Insulated Ground Floors

Our Jetfloor system, has been the market-leading solution for thermally insulated structural ground floors since its introduction in 1982.

It brings together structural and thermal performance in one insulated ground floor solution.

Quick and simple to install, Jetfloor’s flexible configuration design provides a future-proofed robust solution for housebuilders, specifiers and homeowners. Jetfloor was the UK’s first system to use expanded polystyrene blocks combined with a structural concrete topping to provide high levels of thermal insulation.

 

TYPICAL LAYOUT

Jetfloor has been developed to offer simple and robust detailing. The main details are represented here, but for construction purposes please refer to site specific layout drawings by Bison Precast.

Jetfloor was the UK’s first system to use expanded polystyrene blocks combined with a structural concrete topping to provide high levels of thermal insulation.

Design Benefits

  • Flexible U-value performance
  • Improved Psi value due to unique Psi-Block®
  • Thermal mass
  • A+ Green Guide rating
  • Reduced dwelling emission rates

Quality Benefits

  • CE marked to BS EN 15037 and certified by the BBA since 1988 to latest relevant codes and standards
  • All precast concrete products and processes comply with all relevant standards and are manufactured in accordance with BS EN ISO 9001
  • Accredited to BS EN 14001 and BES 6001 responsible sourcing

Construction Benefits

  • Reduced excavation and spoil removal
  • No waste
  • Increased speed of build
  • No specialist skills required
  • Available nationwide
  • Supply only or supply and install
  • Comprehensive in-house technical support

Suitable Applications

  • Residential
  • Standard housing
  • Retirement apartments – ground floors only
  • High-rise apartments – ground floors only

Typical Layout

Jetfloor has been developed to offer simple and robust detailing. The main details are represented here, but for construction purposes please refer to site specific layout drawings by Bison Precast.


1  Wide EPS blocks

2  Narrow EPS blocks

3  Run-out 100mm sheet

4 Edge detail parallel to span

5 Edge detail perpendicular
to span

6 Load supported off floor

7 Staggered bearing


1 Wide EPS Blocks

Section through Jetfloor where wide EPS infill blocks are used either side of a prestressed concrete beam. This relates to NJB1, NJR1 and NJT1 in the load span table.


2 Narrow EPS blocks

Section through Jetfloor where wide and narrow EPS infill blocks are used either side of a prestressed concrete beam. This relates to NJB2, NJR2 and NJT2 in the load span table.


3 Run-out 100mm sheet

100mm thick EPS infill sheet is cut to suit the floor run out, and replaces a standard infill block up to a maximum width of 295mm. Shown here between a narrow block and a wide block but can be placed between any size of blocks.


4 Edge detail parallel to span

Showing edge section where the beams are parallel to the perimeter wall. The narrow EPS infill block is supported on the perimeter Thermalite Psi block and a prestressed concrete beam.


5 Edge detail perpendicular to span

Showing edge section where the beams are perpendicular to the perimeter wall. The prestressed concrete beams bear onto the wall and are set out by the use of the Thermalite spacing blocks. Also visible is the perimeter insulation around the edge of the concrete topping.


6 Load supported off floor

Section through Jetfloor showing where a non-loading partition wall is located above two beams which are concreted together.


7 Staggered bearing

This shows the detail on the internal wall where the prestressed concrete beams are staggered on a single skin 100/140mm wide wall.


THERMAL PERFORMANCE
U-VALUES W/M² K

The measure of heat-loss through the fabric of a building is expressed as a U-value with limiting values set out in building regulations. However, to fully comply with building regulations, the overall dwelling emission rate (DER) must be lower than the target emission rate (TER) when calculated in SAP.

To achieve this, lower U-values may be required. Jetfloor provides a range of U-value options that will help improve the overall DER.

This table demonstrates this range based on specific Perimeter/Area Ratios and insulation material lambda values.

Note: U-values are based on NJB1 beam centres. Actual house-type values will vary dependent on floor layout.

 

 

(‘PSI’) VALUES (W/M K) AND
Y-VALUES (W/M² K)

Heat is also lost through thermal bridges or junctions in a building and is expressed as a Y-value. Its units of measure are the same as the U-value, W/m² K.

To calculate the Y-value, the length of the thermal bridge must be multiplied by the Psi value of the junction of the building being considered i.e. the wall to floor junction.

The Psi value is the measure of the thermal transmittance at the thermal bridge and is calculated using thermal modelling, its units of measure is W/m K.

Jetfloor incorporating Psi-Block® has resulted in significantly improved Psi values as shown on the table above.


Cost Effectiveness

During the development of Jetfloor, we engaged the services of independent cost consultants to make detailed cost comparisons between a range of structural ground floor solutions, including:

  • Suspended in-situ concrete
  • 150 beam and building block
  • 175 beam and building block

Their findings clearly show that, based on similar
U-value performance, Jetfloor is the most cost-effective solution. One of the key areas that helped make the difference was the overall floor thickness, particularly when compared to a 175mm deep beam and block solution.

The reduced floor thickness with Jetfloor will inevitably lead to cost savings through the reduction of dig and spoil removal costs.

When you add the inherent speed of installation and the robust edge details, it is easy to see how Jetfloor will give housebuilders and specifiers cost-effective certainty of compliance with the latest requirements of part L of the building regulations.

Customer Testimonial


“We have extensive experience of housing schemes and helping to deliver value for our clients. We have applied our knowledge to review the new Jetfloor product. Certainly given typical build requirements and site conditions the Jetfloor system provides a good cost-effective solution with the benefit of reduced off site disposal. It would certainly be an option that we would advise our clients to consider on housing projects.”

Comparison diagram


Block Details

Our load-span tables are given as a guide only. Further advice is available on request.


Camber details

Bison Precast prestressed concrete beams exhibit an upward curve known as camber which is a result of the compressive force near the bottom generated by the prestressing tendons. An allowance of span/300 should be taken into account in floor finishes or bearing levels.


Prestressed beam details

BIM Downloads

Loading of Jetfloor
Jetfloor
Jetfloor Membranes
Jetfloor Wider JL edge blocks
End cover of tendons
Bearing requirements
Camber
Trimmer Angles
Stack of beams
Floor U Value
Tolerances
Vents and Air Bricks
Jetfloor Brochure
Jetfloor BBA Certificate PS3
DOP HV Beams
DOP Spacer Block

Load Span Tables

Based on floor finishes of 70mm thick concrete topping having minimum strength class RC28/35 reinforced with either polypropylene fibres, steel fibres or steel reinforcement mesh on insulating sheet material of minimum compressive strength 130N/mm².

Jetfloor - with 1.68kN/m² for finishes

Where 'X' equals effective beam centre

Case Studies

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Sewstern Self Build

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