lapVent: View Message

Author

Date

15:47 06/01/2010

Title

Confusion over postitioning of Vents

It is hard to estimate any one particular job as there are so many variables, but a rule of thumb is one unit every 2-3 rafter bays, staggered along the last full run of underlay for upper level venting. Usually 4 on a average sized straight sided roof - 2 on each side - do not mount them directly opposite eachother though (create a wide ranging gently breathing airflow).

Firstly, thanks for a very speedy supply of the units.

Second, The above reply was given to a question "How many are needed..." on 31.12.2009.
Ridgewatch's comment re "last full run of underlay for upper venting" seems to be in conflict with the general instruction leaflet accompanying the the units, which indicates one unit low and one high on each side of the pitched roof.

My roof has eaves level vents which are clean open mesh.

Question: Should I fit all 4 units at the upper level or 2 low and 2 high?