Spacing plywood or OSB

Probably what causes the most cracks on new construction is shrinkage. Shrinkage cracks are usually small hairline cracks and don't lead to damage. We have been ably to eliminate shrinkage cracks by using admixtures in the finish coat, and by simply letting the brown coat set up for a few days, allowing the mortar to shrink and crack before putting on the finish.

Probably the worst avoidable source of cracks is failing to space the plywood or OSB sheathing an eighth of an inch. But it is not my job to space theplywood. Most of the time, when we show up to do a new house or addition, the sheathing is covered with house wrap or tar paper and we can't inspect the sheathing.

I have observed new houses near me where the sheathing for the walls and roofs is butted tight. These houses look like the ocean when the sunlight hits. The vinyl siding is super wavy and the roofs are worse.

It really hurts to see this kind of workmanship when it can easily be avoided.

Correx roof over a chimney. Correx roof over a chimney.

These instructions are now stamped on each sheet in Spanish and French. Too bad these instructions are neglected.

This great video should explain it all:

Zip wall is easy to space, and 1/8th is also required. It can only be inspected by pulling off the zip wall tape.

I have to say something, because this is a frequent defect that needs to stop.