In early summer 2010, Lars Källered of the company ISODRÄN AB, placed ten different structures of
terrace floor in the castle garden of Ulriksdal, Stockholm. The purpose of the project was to find a
design that could retain sufficient water so as to promote plant growth while the ISODRÄN layer (an
absorbent insulator) drained the excess water.
Terrace floor is a complex structure that is continuously exposed to variable weather, and as such, its
material properties can be affected. In order to keep the waterproof layer warm, it is necessary for
the design to maintain an even temperature between the thermal insulation and floor joists, so a
membrane, warmed from the above insulation, protects the joists. Temperature changes, however,
can render the layers susceptible to movement that can damage the membrane and lead to damp
The terrace floors built during the 1970s and 1980s are currently under renovation, bringing both
economic and design complications.
This thesis seeks to identify the damp damage and investigate how the structure should be designed
to reduce the damage to the underlying joists. The choice of materials is based on a literature
reviews, interviews, field studies, and laboratory experiments. The design of a terrace floor should
preferably be constructed as follows:
250 millimeters of pumice involved soil
5 millimeters of geotextile
100 millimeters of ISODRÄN layer
2,5 millimeters of Resitrix SK
2x10 millimeters of Asfaltmastix
The solution is an atypical construction, designed as an inverted roof where the thermal insulation is
placed above the waterproof layer. The terrace floor concrete must have a slope of at least 1:100,
directly onto which is placed the waterproof membrane (Asfaltmastix), a rubber carpet, ISODRÄN
layer, soil and plants.
The vegetation increases the durability of the waterproof layer as well as having a positive effect on
the city centre. Green roofs such as these beautify the urban landscape by compensating for the loss
of foliage on the ground.