We are getting a new house built in a subdivision by a fairly large builder here in Texas. We opted to have the radiant barrier sheathing installed. We were told the brand they would use is TechShield. As most building processes go the builder changed manufacturer and installed two different randiant barrier sheathing brands; Norbord and Weyerhaeuser.

1) Are Norbord and Weyerhaeuser comparable brands to TechShield
2) It is acceptable that two brands were installed?
3) Regarding sheathing installation, it is ok to see light gaps where the sheathing butts together since this will be covered by the roofing products?

The only difference between regular sheathing and radiant barrier is that it has an aluminum foil applied to it. Any quality material will perform the same and can be mixed.

Depending on the details of the sheathing, the thickness of the sheathing, and the spacing of the truss/rafters often H clips are used to stiffen the roof. And if so that will force a small gap between the edges and that is normal.