Thomas Runzheimer
Bibliographic info:
12th International BUILDAIR Symposium, 25-26 June 2021

Purpose of the work
Especially when dealing with indoor pools the existing ventilation system is often used for negative pressurization on the building envelope to protect the roof structure from damage caused by convection. As seasons change, however, air leaks from the outside lead to high indoor humidity fluctuations. These fluctuations may cause timer shrinkage which ultimately might damage the roof structures consisting of laminated wood.
Method of approach
In the case of straightforward buildings such as residential buildings the airtight layers are mostly refurbished from the inside or outside so as to mitigate or prevent leakages in the roof area. In the case of very complex and large existing buildings, it is often useful, from a technical and economic point of view, to rework large leaks at joints and connections that are comparatively difficult to seal so as to ensure significant improvements in airtightness.
Content of the contribution
When renovating the roof structures of a sports and leisure pool you need to make sure that the year-round climate around the wooden beams is as constant as possible, especially with regard to indoor air humidity. For this purpose, leaks in the air barrier where air can seep in from outside have to be eliminated to the greatest extent possible. During the planning phase special solutions for improving the air seal were developed, with a clear focus on the roof-wall connections. This presentation will illustrate the details of the project and the practical work.
Results and assessment of their significance
By applying sprayable sealing materials we were able to achieve airtightness even for the most difficult connections consisting of all kinds of substrates and materials. After having sealed these areas, the leakage flow rate was reduced by 70 % and the applicable limit value for envelope based air permeability was maintained for the existing building.
Very complex connections which are usually very difficult to seal were sealed with very good airtightness results when using this method. The spray seal was very helpful when dealing with hardest-to-reach areas. It was not always possible to avoid backflows along the trapezoidal sheet. Therefore, while measuring airtightness during the construction phase it was decided to take and implement additional measures which led to important lessons learned for future refurbishments.

For further information please contact Dipl.-Ing. (FH) Thomas Runzheimer at: