I have a client that has been experiencing sever ice damming and they have asked for our help to solve the problem. They own a west facing <!—-> <!—->Cape Cod<!—-> style house. The house has two sets of knee wall, one on the second floor and one on the third floor. The knee wall cavity is not connected from the soffits or to the roof peak. And the soffits are not vented. However, the knee walls are vented through the gables. The roof rafters are 2×4, the house is ballooned framed. <!—-><!—-><!—->
To make things worse, they have retrofitted a forced air heating system to replace their Hot water reds. The heating contractor placed the hot air duct in a new bulkhead on the west side ceiling, just under the knee walls.<!—-> <!—->
As far as I can see the hot air duct is warming the intersection of the first floor and the second floor knee wall, causing the roof to have a hot spots in the winter. The knee wall is not vented appropriately and the warm air sits at the top of the knee wall in the attic. This seems to causing the ice damming<!—-> <!—->
As far as I can see, the best solution is to:<!—-> <!—->
1) Strip the west facing roof. apply plywood roof sheeting over the 1″x6″ roof sheeting<!—-><!—->
2) Vent the soffit<!—-><!—->
3) Try to connect the two knee walls so air flows for the soffit to the peak.<!—-><!—->
4) Install ice and water shield from the soffit to the peak.<!—-> <!—->
5) Replace shingles<!—-><!—->
Does anyone have any other ideas?<!—-><!—->
I am not sure whether to vent the knee wall cavity at the roof as well. If possible, the client does not to see the venting on the west side of the house as it is the side that faces the street.<!—-> <!—->
Replies
If you're going to reshingle and resheath anyway, why not build up the roof with 2X2 to provide a continuous air space between the old and new sheathing. Add in soffit and ridge vents and you're done (except for new flashing etc.). P.S.I'm not sure that I understand the configuration of the structure.
Edited 4/12/2008 2:54 pm ET by sisyphus
or mechanically move the air with solar powered vents---gable or roof--your choice