Publication date: Available online 26 February 2018
Source:Building and Environment
Author(s): Hua Ge, Ruolin Wang, Daniel Baril
Attic ventilation is typically recommended for the removal of moisture build-up caused by air leakage from indoors in cold climates, however, it may also increase the amount of snow and rain penetration into the attic, especially in the extremely cold climates. In northern regions, extremely cold temperatures can cause snow particles to become very fine, which will penetrate vents or unsealed openings. The snow accumulated in the attic would melt at temperatures above zero and penetrate to indoors through the ceiling and cause moisture problems. One of the solutions is to add filter membranes along a ventilation cavity behind the façade to prevent snow from entering the attic. The ventilated attics with filter membrane had some success but there were instances with reported water leakages and moisture damages. There have been also attempts to use un-ventilated cold roofs. Un-ventilated attics prevent snow accumulation but do not allow for effective removal of moisture, which could be risky and prone to moisture damages. This paper presents a field study of the hygrothermal performance of three attic venting systems. Three houses with different attic designs built in Canadian North were monitored: two with a ventilated attic but different strategies controlling snow entry and one with an un-ventilated attic. Measurements show that the ventilated attics had acceptable conditions. The moisture content of wood structure at most monitored locations in the un-ventilated attic remained above 20% through the summer, which indicates that without ventilation the construction moisture and moisture accumulated through winter cannot be effectively removed.
Source:Building and Environment
Author(s): Hua Ge, Ruolin Wang, Daniel Baril