On Tue, 14 Jul 2015 00:54:03 -0400, micky
wrote:

On Mon, 13 Jul 2015 20:55:44 -0400, wrote:

On Mon, 13 Jul 2015 16:44:40 -0700 (PDT), TimR
wrote:

On Monday, July 13, 2015 at 6:12:47 PM UTC-4, Boris wrote:
Hi,

We're remodeling and the old flooring (lino and carpeting) has been taken
up to install hardwood. I noticed many of the 4'x 8' x 3/16" underlayment
plywood has lines of stitching. Yes, stitching, which goes through to both
sides, and is made of nylon or cotton multi-strand thread.

What is this? I've never seen it before.

TIA

Very common in boatbuilding to stitch plywood then epoxy over, but I've not seen it on a floor.

What's the purpose of this? Doesn't the glue hold it together.

I've never seen plywood underlayment stitched, but "fingerjointed
hardwood "or "fingerjointed parquet" is often stitched with nylon
cord.

Same question?
Does "self jigging" ring any bells???