EPS infill blocks and load bearing rails
The EPS infill blocks and load bearing rails provide a formwork to the structural concrete topping; only the load bearing rails make a further contribution to the long-term structural performance of the floor in the form of load spreading once the structural concrete topping has been placed and has obtained its full design strength.
EPS blocks cut to less than 300mm long, to accommodate varying beam lengths, shall be positioned at the floor edges; starter and end blocks should not be more than 300 mm wide at the top.
The EPS blocks are designed to have a normal bearing of 20 mm, with a 5 mm allowance for misalignment and manufacturing tolerances in the straightness of the beam; a minimum bearing width of 15 mm must therefore be ensured.
The EPS load bearing rails have adequate resistance to short-term and long-term creep compression.
To reduce the risk of accidental penetration of the EPS during the construction phase, spacers (4 per m2 and dimensions not less than 50mm x 50mm) for supporting mesh reinforcement should be located on spreader plates over the EPS infill blocks and load bearing rails.
Condensation risk
To help minimise the risk of interstitial condensation, the void space beneath the lowest point of the floor construction shall be at least 150mm high, with provision for adequate through-ventilation.