Styrorail Insulation as a Vapour Barrier

Project Description:

Moisture accumulation issues often arise in finished basements within the Ottawa area. We have compared the heat and moisture transfer of a traditional finished basement wall, a styrorail insulation wall with a vapour barrier and a styrorail insulation wall without a vapour barrier. Through WUFI simulations, we can observe the moisture and heat transfer through each of the wall assemblies and determine any areas where moisture accumulation may occur, leading to possible mould growth. We also considered a warm year and a cold year in Ottawa, to determine if our climate may have an impact on the performance of the wall systems. We did not observe any notable changes in performance between a cold and warm year.

We compared the WUFI results with an ASHRAE standard for moisture transfer through various materials to determine that WUFI was producing an accurate representation of a traditional below grade finished wall assembly. With this information we were able to simulate the Styrorail wall with and without a vapour barrier accurately.

By analyzing the WUFI simulations and through the use of R, we can determine if any one wall will perform better in regards to moisture accumulation and heat transfer. Through the use of R, we can see that there is a relationship between the vapour resistance and the moisture within the wall assembly. We have determined that the Styrorail wall with a vapour barrier will perform better in regards to vapour resistance and moisture accumulation.

While a vapour barrier may not be required with the installation of Styrorail products in all municipalities, we recommend including a dedicated vapour barrier.

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