I just put tar felt underlayment under my shingles when I did my shed.
what a difference between the membrane and felt paper?User452441 wrote: ↑ In most cases, just felt paper.
However if slope is low, the membrane might be a better choice.
Above 2 post covered it well. There is #15 felt, #30 felt, ice and water shield (membrane)
As i'm doing my Gazebo and small area, doesn't it bother instead of using felt paper or synthetic underlay and to use weathertex eave protection all over?User452441 wrote: ↑ Above 2 post covered it well. There is #15 felt, #30 felt, ice and water shield (membrane)
For years #15 felt, and #30 felt was used on the roofs. #30 felt at eaves and in valleys, and then #15 felt over the rest of the roof.
synthetic underlay, is a better product than the above felt.
On the west coast, some roofers will use a #30 felt at the eaves, and valleys, then synthetic underlay over rest of roof. Reason for the #30 felt is to go with code, I am not aware of a synthetic underlay, at the eaves that can meet this requirement. If I am mistaken please correct me.
For the ice and water shield (membrane), in the Vancouver area is not used often (4/12 slope and above), due to the winters we have. In the rest of Canada, I agree in using it at eaves and valleys. I have only seen one ice damming problem in the Lower Mainland in 30 years. Sucks if it is you though.
However we I talk about slope, if your slope of roof is below a 4/12, ice and water should be spec for it. The reason for this, is the slope is that low, that water can get in more easily, and the ice and water will help stop it. Be aware that no shingles should go below a 2/12 slope.
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