In low-level cold stores, with relatively light loads the ultimate load upon the floor insulation can be calculated by using a 45° load spread. High bay stores, which impose very high loads, require a different calculation method. Elastic plate theory treats the floor construction as a series of interacting elastic layers, allowing the combined behaviour of the layers under static or dynamic loads to be modelled and the load on each individual layer to be calculated.
This makes it possible to design floor systems which fully utilise the mechanical properties of each layer. The long-term compressive stress on the insulation should not exceed 2% compression. The maximum design load for STYROFOAM™ - based on EN1606 - is shown in the figure on the right and given in the product data.
The combination of low-weight, high strength and resistance to deformation under heavy single-point loads makes STYROFOAM uniquely suited to cold store floor construction. STYROFOAM offers:
water and water vapour resistance: the closed cell structure makes it highly resistant to water in all forms, minimising the risk of ice build up;
long-term thermal performance: minimal degradation from repeated freeze/thaw cycles;
low thermal conductivity: the required thermal performance can be achieved with minimal thickness of insulation, maximising space utilisation.
STYROFOAM SP-A is recommended for use in cold store floor construction.
Dow manufactures billets of STYROFOAM which are supplied to a network of specialist fabricators. Dow can also supply customers directly with material in bespoke sizes, subject to minimum volume requirements.
STYROFOAM boards should be installed on top of a vapour barrier. To prevent thermal bridging the required thickness of insulation should be made up from two layers of STYROFOAM, laid with joints staggered. A loose laid slip sheet should be used to separate the STYROFOAM boards from the concrete slab.