This film illustrates all steps from stocktaking and evaluation of the existing roof construction including the roof windows and chimneys to the renovation of damaged roof elements and a professional thermal insulation of the roof.
The following explanations of the film are supplemented by architectural drawings and photos, which were created in the course of the research project to convert an old building into a low-energy house.
As the upper limit of the building envelope, the roof is exposed like no other construction to the extreme stresses of rain, snow, wind, cold, and heat. Damage to roof structures, roof coverings, and their connections to skylights, chimneys, and gutters can be the result.
The
examples in the pictures show damage and moisture in the roof structure.
Moisture that penetrates through damaged roof coverings or is caused by the
condensation of air humidity can cause decay.
Insects, fungi, or overstressing by loads can also cause damage to wooden
structures.
Before energy-saving measures are implemented, the existing roof structures must be examined.
If there is any damage to the roof coverings, these must first be repaired.
The picture example shows damage to the slate covering of a pitched roof.
Damage in the thermal insulation can be caused by improper installation and also by moisture in the thermal insulation.
All damaged parts of roof truss constructions must be removed and replaced by new ones.
The thermal insulation must be laid without joints and the adjoining rafters must be fully bonded to avoid thermal bridges.
Defective areas must be filled with the same building materials.
A vapor barrier or vapor retarder, e.g. made of plastic, aluminum foil, or
glass fleece bitumen sheeting, must be laid on the inside of the rafters.
This prevents moist air from the living spaces from entering the thermal
insulation and condensing.
Condensing would considerably reduce the thermal
insulation and cause the roof structure to become damp.
A thermal
insulation fill, e.g. of cellulose, perlite, or crushed cork, is placed between
the inner and outer formwork.
To prevent
leakage, connections to skylights, walls, and chimneys must be sealed tightly.
The thermal
insulation filling can be blown in by machine or processed manually.
As interior lining e.g. plasterboard (as in the picture) or a wood boarding from spruce, pine, or larch wood is recommended.
If the roof covering is renewed as part of a renovation and additional thermal insulation, above-rafter insulation is possible.
The
substructure of the tile roof coverings consists of counter battening,
underlayment, and roof battening.
The roof
coverings must be laid following the roofing rules and the laying instructions
of the manufacturer.
Flat roofs
are more susceptible to damage than inclined roofs.
Damage to flat roof coverings is caused, for
example, by the aging of the sealing membrane, exposure to environmental
influences, and insufficient gradient for water drainage
Thermal
insulation boards are installed on flat roofs in various thicknesses on flat
and clean subsurface.
The boards
are to be installed with a low pre-stressing; they thus remain fixed in
position without additional measures.
Panel
joints and adjoining areas must be fully tied and jointless.
Roof sealing
can consist of several layers of bitumen sheeting.
The top
layer protects against ultraviolet rays and the slope should be at least 2%.
The substructure of the non-ventilated flat roof usually consists of reinforced concrete.
This should already be laid out with a gradient for the planned drainage.
Particular care should be taken to install the vapor barrier and the upper roof sealing to prevent the thermal insulation from getting damp.
The thermal insulation must be sufficiently dimensioned according to the relevant guidelines.
The substructure of the ventilated flat roof can consist of a concrete or wooden beam ceiling.
The thermal insulation must be protected by a vapor barrier against the moisture flowing through from the lower rooms.
The spaces between the wooden beams must be connected to the outside air by ventilation slots to prevent the thermal insulation from getting damp.
The thermal insulation must be adequately dimensioned according to the relevant guidelines.
Roof
windows are essential components of architectural design. Their arrangement and
structure determine the overall impression of the roof surface.
The frames are
often made from the wood of native forests, e.g. pine, spruce, or larch. Wood is
a renewable raw material and can be processed easily. Due to its natural color
and grain, wood has special aesthetic characteristics.
An exterior
cladding, e.g. made of anodized aluminum sheet, protects against rain, snow,
sun, and wind.
The heat transfer
coefficients for roof windows required by the Energy Saving Ordinance can only
be achieved with multi-pane insulating glazing.
Windows
that show greater damage must be removed and replaced with new ones.
The
replacement and new installation of roof windows require constructive measures
in the area of the roof construction.
When
installing the roof window, leaks in the area of the vapor barrier and thermal
bridges must be avoided.
