Retrotec USACE - Manual (Page 393)

Appendix K K5
Composite materials in old fl oors are effi cient for hydroscopic regula- ■
tion (rubbish, sand, scoria).
Composite materials in old walls (mud, rubbish, stones, mortar) manage,
■
by moving the dew point, the different situations of water coming up
from the ground to the air, following seasons and/or occupancy.
Figure K3. Example of traditional techniques without thermal bridge in old buildings.
Unlike new industrial buildings, old buildings have no thermal bridges
(Figure K3). The junctions between wood or iron beams are generally carried
out by arranging open spaces around these parts of the structure. They avoid
the rotting of wood or the rust of iron in contact with masonries.
This technique considerably limits heat exchange by conduction between
the fl oor and the facade. Moreover, when the under fl oor is covered with a
plaster coating, it produces a very slightly ventilated air space, which limits
heat exchange by convection at the junction between the fl oor and the facade.
These technical arrangements in old buildings reduce any effect of thermal
bridge.
K.3.1 Recommendations
It is necessary to have a good knowledge of old building techniques. The struc-
tures and the functions of each wall have to be distinguished. Thermal bridges
should not be created when the existing old buildings do not have any.