Why Vapor Barrier -AND- Tar Paper?
(This thread is duplicated from the discussions on the Bedford (2011) discussions. The episodes I am referring to are 7 and 9)
I am starting to reside our old house myself and found this episode very helpful. We are ordering supplies now and had a question about their materials used...
We have investigated using Cedar Slicker to create air channel behind our cedar clapboard (pre-primed) siding but were deterred by the added cost. We were excited to see that TOH had an alternative of using Furrow strips...
My question is why did they layer vapor barrier below with Tar Paper on top? Wouldn't the Tar paper mitigate the vapor release of the house?? Wouldn't the Typar be enough water shield???
The only thoughts I have had is maybe the open airspace actually creates noise with air passing over the Typar. Or they assumed that an old house would have enough ventilation in other areas that the Typar functioning was not necessary - just for added protection?
Your comments are appreciated!
Jon (in Maine)