The topic of mould has raised it’s head a lot on the refurbishment of older properties we’ve been working on recently.
The excellent video below by Simon McGuinness (PassiveLogical) gives a full and detailed explanation of what’s happening and what you need to do. As Certified Passive House Designers, many of our clients are adopting the Passive House standard in their detailing which insists on thermal bridge free design & detailing; but the problems (for us) occur when working with older properties or with clients reducing the level of insulation and focussed detailing that is required to eliminate mould from a build:
Why this movie by Simon is so incredibly important are the conclusions it draws:
1. The key factor that contributes to mould growth is the detail design and thermal bridge elimination (especially at corners and edges). IT HAS NOTHING TO DO WITH VENTILATION.
2. In order to calculate the frsi the detail needs to be thermally modelled using numerical modeling software to I.S. EN ISO 10211 – an example of such software is Psitherm (screen grab below):
3. Working to the Acceptable Construction details (ACD’s) cannot guarantee that the temperature factor at critical corners is compliant with the Building Regulations in this respect. This puts the Design and Assigned Certifier in an impossible situation unless all details are thermally modelled using psitherm or calculations are available for that specific detail – “it is significantly less than certain that the Assigned Certifier can rely on the ACD”
Screen grab from ACD
Any errors in my conclusions let me know…