White and Grey EPS – What’s the difference?

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solid wal grey eps

Solid wall grey Eps

If you’ve seen external insulation jobs around your area, chances are you’ve seen EPS blocks on the wall – those big lumps of polystyrene fixed to the wall with long pins. You might have seen these blocks in different colours – some are white, some grey and some have little grey spots. So which one is best and what is the difference?

Graphite – the key to EPS high performance

Grey Expanded Polystyrene  one crucial difference to white EPS, and that is simply that graphite has been added to the mixture. Graphite significantly improves the performance of the polystyrene so that you would only need a thickness of 90mm in grey EPS to achieve the same performance as an 120mm block of white EPS. That is a really significant improvement for such a small change in the mixture.

Does Grey Polistyrene cost more?

solid wall insulation eps
Grey eps for solid wall insulation

Solid wall grey eps will usually cost marginally more than white EPS. The cost difference is usually fairly minimal however, so most installers will use grey EPS if they are concerned about performance. There is one reason why you might use white EPS however – it is slightly easier to work with.

White EPS reflects the sun better than grey, and therefore its surface does not get as ‘greasy’ in the heat of the sun. This means it is often not necessary to rasp the white EPS, saving several hours of work for an average installation. Some installers feel that this, combined with a small cost saving, makes it worth installing white EPS.

What are the dark spots in the white EPS?

ewi white eps


Some companies claim that white EPS boards with grey spots are somehow better than other EPS.

This is very much an urban myth – the grey freckles in the board are simply from where the machine that manufactures the boards has not been cleaned after creating grey EPS.

There is no real improvement in performance with this type of board.

 What do we recommend?

We will usually recommend  solid wall grey eps as it has few disadvantages and a better thermal performance than white EPS. If you do wish to specify white EPS however, we can fit it.


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