Siding Questions, & On Tyvek Vs. Felt

Hello:
Have a house with T1-11 (plywood panel type of stuff) siding on it, which isn't in the greatest of shape.
In the Spring, will be having the typical horizontal Cedar Clapboards installed.
The two contractors we've had over both said to place the new clapboards right over the existing T1-11.
Have two questions, please.
One of the contractors says he uses "AYE" quality level cedar clapboards. Guess there are different "quality levels" for this stuff.
a. Is this AYE grade what we want ? Are there "better" cedar siding grades to consider, or is this what most folks use ? Brands, etc. ?
I've asked for pre-primed clapboards, but is there anything else I should be specifying ?
b. Surprisingly, one of them said he does not like Tyvek, and has had poor results with it. He wants to use #15 Felt between the existing T1-11 and the new Clapboards.
I was under the impression that Tyvek was a sort of "standard" these days.
Would sure appreciate any thoughts on this propoised use of #15 Felt rather than Tyvek ?
Thanks, Bob
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In my (non-professional) opinion, felt is as good as tyvek. See <http://www.umass.edu/bmatwt/publications/articles/housewraps_feltpaper_weather_penetration_barriers.html
Cheers, Wayne
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"Robert11" wrote...

Aye is about the best grade therefore it costs more.

The type of nails.

The felt is cheaper and easier to work with, but doesn't act as good of a barrier to air and moisture as tyvek does.
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hawgeye wrote:

Also 15# is a little thin, the stuff breaks down but I'm not sure 30 is used on walls?
If you use felt on a roof 30 is the way to go
cheers Bob
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Bobk207 wrote:

Yes 30# is the way to go on walls. There are some experts out there who recommend felt over tyveck, since it is more breathable. (I still use Tyveck on new construction though. It costs more, but the labor savings over felt is considerable.) Also, there is some concern with Tyveck and cedar--the tannins in the cedar act as surfactants that break up the surface tension of water and allow water to pass through.
I would ask your bidder how they plan to detail the windows and doors so as to prevent water intrusion. They should add some sort of z flashing over the head casing, which is tucked under the building paper. Details like that are more important than whether they use felt or tyveck.
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marson wrote:

Some building researchers suggest two layers of #15 felt to overcome the tanin problem. TB
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I don't think that placing the cedar clapboards over the T1-11 if in poor shape is a good idea but if the shape is OK then yes. The T1-11 is flat so Cedar shingles would work fine. If the T1-11 is not in good shape I would remove it, see what sheathing is behind if any, and replace it with 5/8" plywood or Oriented Strand Board and then the the better Cedar Clapboard.
I do think that if you want better construction don't use the Tyvek the 15# Felt it has been used many years as a standard.
CID...

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Take a look at how the T1-11 aligns with the window and door trim. If it is close to flush, the T1-11 should be removed or else the new siding won't line up right.
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If you have rot in the T1, the T1 should be removed. Felt is recommended under cedar.
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