Invändig tilläggsisolering : köldbryggor, fukt, rörelser och beständighet : thermal bridges, moisture problems, movements and durability = Internal additional insulation

Forskningsoutput: AvhandlingDoktorsavhandling (monografi)


The report deals with the problems which may be caused by internal additional insulation of an existing building component.

Problems treated in this report are heat losses through and surface condensation at thermal bridges, condensation in the building components, stresses due to temperature and moisture content variations and possibly frost damage in facade materials.

After internal insulation thermal bridges such as joist connections, inner wall connections and window splays have relatively speaking an increased effect on heat losses through an outer wall. Computer calculations have been made to estimate this effect. Thermal bridges also reduce surface temperatures in a room. This way in some cases increase the risk for surface condensation. The effect is, however, relatively small.

Condensation in a building component is likely to occur if the internal insulation is made without a new vapour barrier. The condensation risk is naturally greatly influenced by the climatic conditions and the moisture capacity of the building materials.

Onedimensional nonstationary calculations of the temperature and moisture field in some building components before and after additional insulation have been made with a computer program.

Laboratory investigations of thermal and moisture conditions in two
types of walls after thermal insulation have been made.

The effect of driving rain on the moisture content in an outer wall with and without internal insulation has for some cases been calculated. The possible risk for frost damage due to the decreased rate of drying out is discussed. Although internal insulation can be said to affect the frost resistance, other factors surely have greater influence.

For the discussion of stresses due to temperature and moisture variations simple structural elements are used, plates with clamped and free edges, respectively. The temperature field and the moisture content before and after internal insulation have earlier been calculated. These calculations are now used in order to determine the effect of internal insulation on such stresses. Some calculations with the finite elem ent method have also been made in order to study more complex stress fields.

As for thermal stresses, internal insulation affects the stress distribution in a wall rather than the maximum stress. Stresses due to moisture content variations are hardly affected by internal insulation.


  • Ann-Charlotte Andersson

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Husbyggnad


Tilldelande institution
Handledare/Biträdande handledare
  • Nevander, Lars-Erik, handledare, Extern person
Tilldelningsdatum1979 maj 23
  • Byggnadsfysik LTH, Lunds Tekniska Högskola
Tryckta ISBNTVBH-1001
StatusPublished - 1979
Externt publiceradJa