I'll probably ask my Alpen rep but thought I'd pose the question here first, opting to feel embarrassed here than elsewhere (picking my poison).

On the Building Science site, there are several mentions, diagrams, videos showing flexible membranes installed prior to the window installations.

Some of those membranes are sill pans and some wrap 360 degrees around the rough opening.

Where do you get these?  I'd have to go back to the BSC site and review but I think I remember Tyvek logos being on the membranes?

I'd also like to hear comments about bet practices on these membranes.

Thoughts.

Dow makes an inexpensive lightweight window pan, available at Wind-Lock.com. Schuco makes an aluminum one, available in different sizes. One big issue with Dow Flexible flashing is that very few things stick to it, and it is hard to air seal. SIGA tape is great for wrapping corners. Most of the better components are not sold at your typical local supplier.

Typically, no; they are not supplied with the window order, although they are happy to recommend a type and the instructions almost always recommend them. You need to supply the window membranes. If you have factory installation of the window, the installers will come with membrane. Some window manufacturers also offer pans you can order at the same time you order the windows. They are, of course, extra cost. Typically, they aren't custom made, but they are custom-adjustable.

I like: http://www.jamsill.com products. Easy to install and use. In a pinch, I have made the sill slope with cedar shingles and then use zip sheathing tape to make a waterproof pan. You have to be very careful if you use a membrane pan as opposed to a premade hard one as it is easy to tear the membrane installing the window. Cheers, Eric

From what I've been able to ascertain, aluminum sill pans bear the risk of some minor condensation, since aluminum transfers heat differently, changing the dew point. Perhaps I'm splitting hairs and perhaps I'm over generalizing on this.

At any rate, if I was to consider flexible membranes around the window rough opening, what brands should I consider?

One company that looks like a good product is Grace Vycor. I think Tyvek also offer a product. Most of this stuff comes in rolls (varying widths). Is this correct? the membrane stops at the drywall, wraps around the outside edge of the rough opening and overlaps the WRB wrap creating a seal... correct?

I'm trying to get some anecdotal info on people's experiences with the Dow flexible membranes and may call Wind-Lock.

thermal bridging & therefore condensation, should not be an issue with an aluminum pan since the pan sits outside the thermal envelope.

SIGA tape is far superior to the others, and I've used them all. They use a non toxic, acrylic adhesive rather than a petroleum based one, sticks to almost anything and is far more flexible. It's also more expensive, but it is worth it. Sold thru dealers around the country, you can google it & find a dealer near you.

As a builder i'm always very conscious of cost, but some things are worth paying more for, for their performance durability and lack of issues.

Fortiflash
Dupont Flex wrap
Siga
Tremco

Use plastic shims, NEVER cedar.