Abstract
In most Nordic homes the interior surfaces of walls and ceilings have some kind of surface treatment for aesthetical reasons. The treatments can for example be glass felt or glass fibre cloth which are painted afterwards.
To evaluate the hygrothermal performance of walls and ceilings it is essential to know how much influence a surface treatment has on the water vapour transport. Traditionally, there has been most focus on paints that affect the permeability as little as possible. However, sometimes water vapour
resistance is desirable. Especially, this is relevant in existing buildings with a ventilated attic where the ceiling may be air tight but has no vapour barrier; post-insulation of the attic may cause the need for a vapour barrier. Placing a vapour barrier above the ceiling can be tiresome and it is difficult to
ensure tightness. A simpler way is to paint a vapour barrier directly on the ceiling e.g. as an ordinary paint.
This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface treatments. The surface
treatments were glass felt or glass fibre cloth with different types of paints or just paint. The paint types were acrylic paint and silicate paint. The results show that the paint type has high influence on the water vapour resistance while the underlay i.e. glass felt or glass fibre cloth has very little impact.
The measured water vapour resistance for specimens with acrylic paint was the highest, these were measured to be up to approximately 3·109 Pa·m2·s/kg which is considerably less than 50·109 Pa·m2·s/kg as recommended for a vapour barrier. Therefore, two layers of ordinary acrylic paint on glass felt or glass fibre cloth cannot be used instead of a vapour barrier.
To evaluate the hygrothermal performance of walls and ceilings it is essential to know how much influence a surface treatment has on the water vapour transport. Traditionally, there has been most focus on paints that affect the permeability as little as possible. However, sometimes water vapour
resistance is desirable. Especially, this is relevant in existing buildings with a ventilated attic where the ceiling may be air tight but has no vapour barrier; post-insulation of the attic may cause the need for a vapour barrier. Placing a vapour barrier above the ceiling can be tiresome and it is difficult to
ensure tightness. A simpler way is to paint a vapour barrier directly on the ceiling e.g. as an ordinary paint.
This paper presents the results of an investigation of the water vapour resistance of surface treatments which are commonly used in-door. The water vapour resistance was measured by the cup method. Aerated concrete was investigated with and without various surface treatments. The surface
treatments were glass felt or glass fibre cloth with different types of paints or just paint. The paint types were acrylic paint and silicate paint. The results show that the paint type has high influence on the water vapour resistance while the underlay i.e. glass felt or glass fibre cloth has very little impact.
The measured water vapour resistance for specimens with acrylic paint was the highest, these were measured to be up to approximately 3·109 Pa·m2·s/kg which is considerably less than 50·109 Pa·m2·s/kg as recommended for a vapour barrier. Therefore, two layers of ordinary acrylic paint on glass felt or glass fibre cloth cannot be used instead of a vapour barrier.
| Original language | English |
|---|---|
| Title of host publication | NSB 2014: 10th Nordic Symposium on Building Physics 15-19 June 2014 Lund, Sweden : Full papers |
| Editors | Jesper Arvidson, Lars-Erik Haderup, Anders Kumlin, Bitte Rosencrantz |
| Number of pages | 6 |
| Place of Publication | Lund, Sweden |
| Publisher | Lunds Tekniska Högskola, Inst. för Byggnadsteknik |
| Publication date | 2014 |
| Pages | 1030-1036 |
| Article number | 128 |
| Chapter | Moisture Safety III |
| ISBN (Electronic) | 978-91-88722-53-9 |
| Publication status | Published - 2014 |
| Event | 10th Nordic Symposium on Building Physics - Lund , Sweden Duration: 15 Jun 2014 → 19 Jun 2014 Conference number: 10 |
Conference
| Conference | 10th Nordic Symposium on Building Physics |
|---|---|
| Number | 10 |
| Country/Territory | Sweden |
| City | Lund |
| Period | 15/06/2014 → 19/06/2014 |