Fire spread in polystyrene 'sandwich' wall moulding systems

[messy]

During a recent episode of TV's Grand Designs, the use of hollow polystyrene blocks/moulds were shown, The rectangular moulds are clipped together (lego style) and secured. Occasional reinforcement bars are added and concrete poured into them. The result being a quick & easy walling system.

The polystyrene moulds are left in situ (thereby creating the require U/insulation value) and rendered over. I have seen this used in a basement area, but the TV show demonstrated it's use from ground to roof level.

The question is, with apparently no fire stopping within the polystyrene 'sandwich', what is in place to stop uncontrolled, unseen and undetected fire spread vertically up to the roof level? or is this polystyrene treated in some way?

[dave bev]

try here - without wanting to promote any one organisation/provider  of such building systems - i assume others meet the same standards of 3 hours

http://www.polystyrene-products.com/blocks.htm


dave bev

[Chris Houston]

I would ask to see independent fire data before believing it would have any fire resistance.

It is worth remembering that the fire resistance of a item in labratory conditions will differ from that real performance once it's been stuck to a wall and had the render kicked off by the local kids over the period of a few years.

[wee brian]

Fire resistance isnt really the issue. Lots of materials that burn like crazy can be used in constructions that have fire resistance. The concrete is doing all the work.

If used in a single family dwelling house I doubt that this type of construction would be a big deal. The chances of a fire spreading behind the render would be low in my view. The EPS would melt and the render would fall off.

[Apollo_SG]

do not be unduly alarmed. the amount of mould used to clip the boards together is not substantial (calorific value) to be of substained burning. plastic moulds are generally used for raising reinforcement bars to concrete floor slabs too.

if you consider the quantity of (combustible) glass fibres used as binders for reinforcing gypsum in building boards, per volume basis, I would safely say there is less plastic mould in such blocks.