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.
- 150mm or 225mm prestressed beam
- Thermalite spacer block
- EPS infill block
- Psi-Block
- Damp-proof course
- Structural grade overlay sheet min strength 130N/mm2
- Structural concrete topping
- Membrane if required
- Air vents
- Perimeter insulation (if required)
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
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
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
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
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.
| U-value W/M2 K | ||
|---|---|---|
| P/A | White EPS 0.038 | Grey EPS 0.030 |
| 0.3 | 0.160 | 0.137 |
| 0.4 | 0.168 | 0.144 |
| 0.5 | 0.174 | 0.148 |
| 0.6 | 0.178 | 0.151 |
| 0.7 | 0.182 | 0.153 |
| 0.8 | 0.184 | 0.155 |
(‘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.
| Floor detail | PSI value W/M K |
|---|---|
| Jetfloor | 0.03 to 0.10(1) |
| Accredited construction details | 0.16(2) |
| SAP conventions document details | 0.32(2) |
(1) Values based on wall U-value of 0.28 W/m2 K floor U-value of 0.15 W/m2 K.
(2) From SAP table K1.
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.
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
Client 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."
Bison Precast request a quote
Our experts are on hand to provide you with the most cost-effective solution, and can provide guidance at every stage of a project, from concept to completion. We will work with you to deliver practical support from the earliest design stages, specifying the most appropriate products and solutions from the Bison Precast range.
Bison Precast technical enquiry
From concept to completion, our experts are on hand to provide technical guidance at every stage of your project. By working with you from the earliest design stages, we can specify the most appropriate products from the Bison Precast range to help you select the most cost-effective solution.