The parts of buildings with increased heat transmission are simply called thermal bridges. The internal surface temperature of these building parts is significantly below the surrounding surface and ambient temperature.
MOST FREQUENT THERMAL BRIDGES
The most frequent thermal bridges are the socle, ring beams, lintels, radiator enclosures, parapets, reinforced concrete pillars, window sills, etc.
The absence of proper prevention of thermal bridges can cause significant heat loss. The moistness generated by surface condensation has a contrary effect to the comfort of the room. Low temperature of the inner surfaces occurs high relative humidity. It is often a breeding ground for mould-growth, surface damages and aesthetic problems. Preventing the development of thermal bridges should be taken care of in the design phase.
Thermal insulating by RAVATHERM™ XPS 300 WB may result significant advantages:
• Reduction of heat loss – energy saving (the transmission heatloss can be reduced with cca. 10%),
• Avoidance of mould-growth,
• Prevention of structural problems:
• surface condensation,
• aesthetic problems,
• crack formation.
• Comfort improvement,
RAVATHERM XPS 300 WB insulation boards are
• not sensitive to moisture,
• frost resistant,
• resistant to mechanical impacts,
• therefore retain the insulation value and strength during and after the construction period.
Due to the high resistance to water-vapour permeation, no vapour barrier is normally required when the insulation is situated on the internal side. To avoid thermal bridges, the accurate design of the structural details has decisive importance. The insulation value at thermal bridges and socle is recommended to be at least equal to the performance of the adjoining walls, roof or floor slab.
Thermal bridges require special attention because, arising from the intensive thermal insulation of the surface, heat flux density and vapour migration are even more intensive at the critical structural nodes.
RAVATERM XPS 300 WB boards can be favourably used as the thermal insulation of reinforced concrete structures: ring beams, lintels, pillars, columns as their permanent insulated formwork, as well as in window frames, parapet walls and building socles. The thermal insulation of the edges of flat roofs, parapet walls, are often not or only insufficiently resolved, which may considerably decrease the efficiency of the thermal insulation of the roof surface depending on the geometrical proportions.
INSTALLATION OF RAVATHERM XPS 300 WB
The RAVATHERM XPS extruded polystyrene foam thermal insulation may be installed as early as before concreting as permanent insulated formwork or subsequently by gluing. In both cases, it is recommended to use additional mechanical fastening.
Arising from the relatively high resistance of XPS boards to vapour-diffusion, vapour condensation created in the connection plane of the thermal insulation and the wall usually does not reach the critical level. In the case of normal internal air conditions (20°C, 50-60% rel. humidity), condensation in the structure, in general, reaches only an extent that dries up in the summer period.
If the existing wall is made of bricks with relatively good thermal insulation value, there will be usually no vapour condensation. However, in buildings with high air moisture content (swimming pools, laundries, kitchen plants), a vapour barrier will have to be installed on the internal, warm side of the thermal insulation, and its efficiency checked by calculation.