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cedar roof underlayment

22K views 18 replies 9 participants last post by  Deejay Henderson 
#1 ·
whats the proper underlayment for cedar shakes. is it tar paper at each layer or can i use these new products such as trace underlayment . the old way seems to work fine when done right...some contractors are pushing the new type of underlayment

any info on install would be great
 
#2 ·
I have not heard anything about that Trace product, if you could provide a link, I would research it for you and get some other roofers feedback on it.

But, the shake-liner felt has been more than adequate for the past 100 years or so, so I doubt it is a very big improvement regarding the cedar shakes.

Ed
 
#5 ·
i agree... felt would be fine..he has been pushing the "better underlayment "
because the roof will not be put on for some time and we need to protect the plywood from water.... and the synthetic would not wear out for months where as the feltr might wear out pretty fast.
its more more money but provides better temporary protection
 
#12 · (Edited)
felt to waterproof,and cedar breather so your shakes can dry out and not rot---will give the cedar much better life,wouldn`t do cedar on a solid deck without it
and if you`re on slats ,forget the felt and breather entirely-I like that best
 
#13 ·
RE: Cedar Roof Underlayment

Hello,
I made a decision about 18 months ago to transition our underlayment use to synthetic. Went through a lot of different brands and types to find the right ones. Depending on the roof covering (tile, shingles, metal) we might use either Grace, RoofTop Guard II, or JM DuraBase. Each have their advantages, but price was not one of them (in southern CA, about $15.00 a square). Went out to do some price checking a few days ago, and found that 30 lb felt now goes for $23.59 a roll (or $11.80 a square). To me, that was the final piece of the puzzle, as to why it was a good decision to get away from organic. As long as asphalt is the primary component, the price will continue to increase for the foreseeable future. My guess is that within 3-6 months, organic and synthetic felts will be price-equal. And when you take in the fact that you can throw 3 10-square rolls in your truck, and felt in a house in an hour or so, the labor savings seals the deal for me.
 
#14 ·
ceder breather

thanks for all the correspondence. I am almost there.

in my area( nothern suburb of chicago) the cedar breather is hardly used.

of four major roofing contractors not one is recommending it. I think its a no brainer..
one says it effects the appearance of the roof by not laying flat... and feels spongy. one says its unnecessary..one says no one uses it because of the cost.

do you think its because they are unfamiliar with the product or what.

My house has alot of sun. full exposure from south and west..what about using just on the shady sides.. east and north.. were its take longer to dry out?
 
#15 ·
MAMA SAID IF THE OTHER BOYS JUMP OFF THE BRIDGE AND DIE,WILL YOU BECAUSE THEY DID,--use the cedar breather on everything,there is no lumpiness,etc-it lays uniform---all areas of your roof get wet,and need to dry,even sunny areas will not dry out moisture trapped under the cedar,and that is why you need the cedar breather
 
#19 ·
Underlayment is required under cedar shakes according to the Cedar Shake & Shingle Bureau (CSSB). The shakes can be installed on battens with #30 shake felt underlay or directly on a wood deck with underlay (#15 plain ir synthetic).
I prefer the felt underlay with the cedar breather on top. Ice shield membranes are vapor barriers so completing the whole roof with it might be a problem if the venting is inadequate.
 
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