The Robust external walls are 115mm thick (inland) and 130mm if built in regions within 15km of the coast. Internal walls are 90mm thick.
This compares very favourably with plastered brick walls of 260mm externally and 150mm internally to create more space internally with the same external area dimensions.
In a 40m² RDP (BNG) Type residential dwelling, an additional internal area of 4-5m² is added to the home.
This is equivalent to that of a 45m² brick and mortar dwelling built the conventional way.
This is all achieved with better thermal performance and similar performance on all other requirements.