Dwelling Type Definition for Air Tightness Testing

Dwelling type – for the purposes of air tightness testing, is the allocation of each dwelling on a development to a generic dwelling type by the person carrying out the air tightness testing. To be classed as of the same dwelling type the dwelling should comply with all of the following – (a) be of the same generic form (i.e. detached, semi-detached, end terrace, mid-terrace, ground floor flat (inc. ground floor maisonette), mid-floor flat, top-floor flat (inc. top-floor maisonette)); (b) be of the same number of storeys; (c) be of the same design air permeability; (d) have similar adjacency to unheated spaces such as stairwells, integral garages, etc.; (e) have the same principal construction details (as identified by Accredited Construction Details or bespoke construction detail reference codes); (f) have a similar (±1) total number of significant penetrations, (i.e. windows, doors, flues/chimneys, supply/exhaust terminals and waste water pipes); and (g) have envelope areas that do not differ by more than 10%.