One More Reason Why Not Lauan
You can Make the Call!
Photo 3 shows the degree/level of penetration the fasteners had into the lauan underlayment. Photos 7 & 8 show just how far the 7/8-inch staple went into the lauan.
Where's the patch? "What patch?" was the answer I got! There was no patch used at underlayment seams or in the field. So what causes do we see so far? We see fasteners so deeply recessed that they have gone through the top layer, and into the core. We see spacing of the field fasteners on or about 6 inches on center. Sure the underlayment seams got 1 fastener per inch, but the field of the panel should have been 4 inches on center, and no patch.
Would've could've and should've used a patch.
But due to the surface of the lauan being compromised by the depth of the fasteners, I don't believe any type of patch would have kept moisture out. And the moisture in the patch could very well have caused the same condition.