I can only sympathize. There is no way to install blinds inside Andersen 400 series T/W windows. I am sick about it and would not have purchased them had I known. I have 4 installed now, with 12 more sitting in the garage waiting for installation. They were custom order, so no refunds... Andersen said " ...we do not sell windows to be compatible with third-party accessories..." It never occured to me to check to see if blinds would work inside the window - I thought all windows were made that way for years.

Yes, exterior, but white isn't an option unfortunately... Would you know what type of caulk or glazing material I should use?

I have decided to go the full frame replacement. I have been looking at various types of sill pan flashing. One product that I like (at least the idea behind it) is the Protectowrap Sill Pan Drainage System. It is installed over flexible membrame flashing and it is layer of sloped foam covered in a water wicking material designed to draw any moisture into the flashing and away from the interior of the structure or so it seems. Most methods I have read about use either a metal sill pan, liquid flashing or flexible membrane. The Sill Pan Drainage System seems like an added bit of security assuming your initial flashing and window sealing is done properly. My question is: Is it worth it? I got a quote for 100' (of which I will likely need about 50') for just shy of $250. Most flexible membrane flashing and liquid flashing is about $40-60 for 50-75' depending on width. Any thoughts or perhaps other practical ideas for making the best possible water tight/ optimal draining sill pan? I'm not trying to be cheap, just practical. This product must be special ordered whereas most of the other protecto wrap products can be bought off the shelf leading me to believe that the Sill Pan Drainage System is not commonly used in my area ( Austin TX) either because it is not needed or due to cost or better alternatives .

The only acceptable solution I've found is to drill into the vinyl casing and installed the inside mount blind that way. We have Atrium vinyl windows and this will void the warranty. But with only 1 year of warranty left, I'm not gonna worry about it. Had I realized this upfront, I would have done a better job on my homework and would have chosen a different vinyl window mfg. Window World in my area will allow you to drill and mount on the vinyl casing without voiding the warranty. But that is 20/20 hindsight. So a couple days ago we finally got tired of living in a fish bowl and ordered blinds for the recently renovated first floor.