HI -- I think this is something you need to ask the supplier of those windows . I have seen in the past that a builder had to pull the windows and have the wrap done to pass inspection. Warranties are subject to said manufacturers of the windows . So this is a question and issue for them and not for here .

The WRB (housewrap) is of a lesser concern in my opinion than is taping in the bottom flange and not allowing a pathway for the water to escape on the random chance it does get behind the wall.

Every manufacturer provides highly detailed installation instructions and yes, if installation does not comply with the instructions, the warranty is typically voided and the windows may perform poorly. I would insist that the builder provide the instructions he is working to, show that they are the correct obstructionist for your model of window, and prove that he is complying. If you get pushback, call the window manufacturer for guidance. Good luck!

Thanks all. I agree this is a question for the manufacturer, but was also hoping to gleen from all those out there that have experience, which you’ve shared and I’m very thankful for! These are All Ultrex Integrity windows. I’ve read the warranty, the installation instructions, and even watched the videos that are linked in the online instruction manual. again, not sure how strict they are regarding installation methods. I will try to find out more. Maybe I can have the roofing/ siding installation crew rip off that bottom tape as a last resort. Waiting on a reply back from the installer. Would welcome any additional comments!!

The warranty on the product will remain in effect, but they will no warranty the performance against leaks.

"Regional standard practices, environmental conditions, and codes may vary and supersede the procedures contained within..."

This window is mounted outside the sill so there is no reason to slope it as the window protects the sill. If it had been mounted in a recessed opening, I would slope the outer sill.

That "tape" is window flashing. Some installers use between window and framing as well as over the top of the frame along with caulking. In CA we normally apply wraps or construction weatherproofing for stucco after windows are installed, slipping it under or over where appropriate.

Yes, I see it is flashing tape. However, they put an additional strip of it under the window.

As mentioned before, ensure that the installer follows the manufacturer's instructions. See: https://www.marvin.com/WebDoc/Window%20Rough%20Opening%20Prep%20and%20Flashing%2019913776.pdf for Marvin prep and flashing installation.

Flange-mounted windows require a flashing on the house-framing. This provides protection when the windows leak and provides a route to the drainage plane.

Also, generally, see Fine Homebuilding on window installation.

If this is a tract home, your protestations may mean nothing as it's not your home and the installers are not answerable to you.

As a builder, it was hard enough insisting that regardless what you've done before, this is the way I prefer it to be done.

That FHB article is a good one but written before vapor permeable tapes were widely available in the US. Spray foam applied from interior is not a reliable air seal, one of the most important qualities of a good window installation. Without a good interior tape available, I would still prefer backing rod and caulk to canned spray foam only. This more recent FHB weatherproof window installation article covers our preferred processes.

The 3M 8067 tape is great stuff but I wouldn't trust it over regular OSB without a primer applied first, to help fill the voids. Your pictured application could still work if the 3M tape is used as a smooth surface to tape the final layer of housewrap to. The biggest issue is the taped bottom flange and it would probably be easier just to cut the tape right below the flange than attempt to remove the tape. Without a properly sloped/backdam and flashed sill, that step would be questionable anyways. If a window is exposed to wind blown rain, it should have a flashed sill, even with an outie or exterior flange window install.

Without a good interior tape available, I would still prefer backing rod and caulk to canned spray foam only.

I've found that the r.o. sizes provided by the window companies leave a gap around the window units that only foam can properly fill. I do like the idea of grinding down the bottom of the frame instead of messing with sloped flashings. But around windows I'm much more interested in preventing water damage than getting passive-house tight.

All, the installers came back. The window sill was flashed up the sides, on the sill, and down onto the plywood properly So nothing to fix there. They added the corner gaskets that came with the windows. And cut the extra flashing tape that they put over the bottom flange. They added the house wrap and properly layered everything in the correct order. I also called Marvin/Integrity and confirmed that the corner gasket and untaped bottom flange + skirt were necessary for the warranty and she confirmed they were critical. I’m very pleased with the cooperation of our installers and the quick response. Thanks to all you guys too for confirming my concerns!