Thermal Floors

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O’Reilly Concrete Hollowcore Thermal Floor slabs are pre-stressed concrete elements with continuous longitudinal voids formed using polystyrene void formers. Innovative casting system in the manufacture of pre-stressed flooring units gives many advantages compared to traditional hollow core units:

  • better sound resistance
  • improved thermal efficiency
  • flexibility in design
  • structural efficiency

POLYSTYRENE VOID FORMERS

The standard width of the slab unit is 1200 mm. Slabs are manufactured up to exact site dimensions with pre-formed service openings where required. the range of depths and achievable spans cover all types of residential houses and the most of commercial, public and industrial buildings.

SOUND RESISTANT FLOOR SLABS

Thermal Flooring Infographic

Benefits & Details

Because our cores are made using Kore™ polystyrene formers, our units are also a great acoustic barrier between floors where sound pollution is a concern, such as in residential and office buildings.
  • Speed of Erection – O’Reilly hollowcore floors can be installed up to 500 square metres per day, saving time on site and reducing overall program of works
  • Reduced Weight – O’Reilly hollowcore floors have polystyrene infill reducing overall weight of floors; this means­­ reduced loads transferred to the foundations and smaller foundation size is required
  • No Open Voids – O’Reilly hollowcore floors have solid ends; this eliminates the risk of water or other contamination in cores
  • No Additional Work on site is required to close open cores
  • No drilling and cutting – all service openings can be easily formed in hollowcore floor slabs at production stage; slabs are manufactured up to exact site dimensions
O’Reilly Thermal Floor slabs have big voids filled with polystyrene which reduces the overall weight of the slab; this means reduced dead weight and better ability to resist service loads, reduced loads are transferred to the foundations and smaller foundation size is required
All service openings can be easily formed in floor slabs at production stage; in a controlled factory slabs are manufactured to the exact site dimensions, improving health and safety on site. Slabs are individually designed to support maximum expected loads.
O’Reilly Thermal Floor slabs have a minimum fire rating of 1 hour; unlike extruded units they have closed solid ends which improves fire retardation
  • the use of high strength concrete and pre-stressed steel offers better span to depth ratio and strengths far greater than the traditional floor systems
  • improved shear resistance gives additional safety at construction phase and in use
  • part of slab can be manufactured as solid to allow for point loads
  • additional top reinforcement can be cast in slabs for cantilevered action
  • effective shear key designed up to BS EN 1168:2005 ensures composite action between Hollowcore slabs and transverse load distribution
  • Hollowcore planks can be used to form a diaphragm to resist horizontal forces
  • Hollowcore planks can accommodate all specific tying details for progressive collapse requirements

150 mm deep Hollowcore slab

Self weight of precast unit (without structural screed):  2.59 kN/m2
Concrete strength at service (28 days):  50 N/mm2
Concrete strength at transfer:  30 N/mm2
Prestressing strands: 7 wire 9.3 mm strand
Prestressing: 70% fpu
Maximum number of strands: 14
Cover to strand: 25 mm
Fire resistance (BS8110: Part 1:1997; Table 4.9): 1 hour
Minimum required effective bearing width (BS8110: Part 1:1997; Clause 5.2):
On concrete: 55 mm
On structural steel: 40 mm
On masonry: 65 mm:
150 mm deep Hollowcore slab

Self weight of precast unit (without structural screed):  2.59 kN/m2
Concrete strength at service (28 days):  50 N/mm2
Concrete strength at transfer:  30 N/mm2
Prestressing strands: 7 wire 9.3 mm strand
Prestressing: 70% fpu
Maximum number of strands: 14
Cover to strand: 25 mm
Fire resistance (BS8110: Part 1:1997; Table 4.9): 1 hour
Minimum required effective bearing width (BS8110: Part 1:1997; Clause 5.2):
On concrete: 55 mm
On structural steel: 40 mm
On masonry: 65 mm:
250 mm deep Hollowcore slab

Self weight of precast unit (without structural screed): 3.59 kN/m2
Concrete strength at service (28 days):  50 N/mm2
Concrete strength at transfer: 30 N/mm2
Prestressing strands: 7 wire 9.3 mm strand fpu = 1700 N/mm2
Prestressing: 70% fpu
Maximum number of strands: 14
Cover to strand: 25 mm
Fire resistance (BS8110: Part 1:1997; Table 4.9): 1 hour
Minimum required effective bearing width (BS8110: Part 1:1997; Clause 5.2):
On concrete: 55 mm
On structural steel:  40 mm
On masonry: 65 mm
300 mm deep Hollowcore slab

Self weight of precast unit (without structural screed): 4.09 kN/m2
Concrete strength at service (28 days): 50 N/mm2
Concrete strength at transfer: 30 N/mm2
Prestressing strands: 7 wire 9.3 mm strand fpu = 1700 N/mm2
Prestressing: 70% fpu
Maximum number of strands: 14
Cover to strand: 25 mm
Fire resistance (BS8110: Part 1:1997; Table 4.9): 1 hour
Minimum required effective bearing width (BS8110 Part 1:1997; Clause 5.2):
On concrete: 55 mm
On structural steel: 40 mm
On masonry: 65 mm
BETTER THERMAL PROPERTIES
O’Reilly pre-stressed Hollowcore floor units have better thermal properties than slabs with open hollow voids due to completely closed cores filled with polystyrene. The air movement in traditional hollowcore slabs reduces their thermal performance. The thermal performance of standard O’Reilly Hollowcore floor slabs is 25% better in average com- paring to the same slabs with open voids.

THERMAL MASS EFFECT
Thermal mass is a property that enables precast concrete floors to absorb, store, and later release significant amounts of heat. Buildings constructed of concrete and masonry have a unique energy-saving advantage because of their inherent thermal mass.

Below is a comparison of U-value between our standard Hollowcore slabs and the same slabs with open voids; lover U-value means better thermal insulation:

Slab Depth U-value U-value
for O’Reilly standard Hollowcore slab for the same slab with open voids
150 mm Hollowcore 1.719 2.449
200 mm Hollowcore 1.481 2.003
250 mm Hollowcore 1.317 1.722
300 mm Hollowcore 1.192 1.522

The thermal performance of standard O’Reilly Hollowcore floor slabs is 25% better in average comparing to the same slabs with open voids

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