kennyrayandersen wrote:BTW, one thing about Masonite is that it is heavy -- not quite twice as heavy as poplar plywood of the same thickness. and nearly 50% heavier than Luan. you will save nearly 40 lbs from switching from Masonite to Luan assuming 10 sheets (inside and outside). If you can find poplar plywood, you'd save around 60 over a Masonite build. I'm just not 'feeling' the Masonite.
I think the bad that I have heard about masonite is that is water even touches it, say bye bye Jenny. So you don't let water touch it with out copeus amounts of epoxy.
What I have heard bad about Luan is that it has more voids internally which can lead to cracking during installation and moisture forming in the voids.
Just what I've read that's all, each has their con's. In a perfect financial world lay down some 1/8" Baltic Birch and be done with it! Unfortunately this is not a perfect world

Personally I used three sheets of 4x8 Masonite under the AL (4 foot sections laid sideways with 3 feet of cut offs). Makes ya wanna build a 4 foot wide I tell ya!