Generally that brake metal "capping" is installed over solid wood. So yes, caulk is the normal application at that point. Silicone is the prefered caulk for its water resistance, adhesive properties and and also its flexability. Obviously if there is excessive movement (as in your case from the sounds of it) it may not adhere properly or efficently. Do you know what the caulk was that was used? If it is not 100% silicone it very well may not have adhered correctly or it released from stretching.

I'd almost be positive that there is wood underneath. They should of put in nails underneath the window and could have put one next to the casing to hide them. I think they did not tightl fit the casing to the sill and left to big of a joint perhaps..

i prefer. the aluminum to have a nice tight fit at this joint which would require no caulk there..the aluminum should also run under the casing and window, this would allow water a place to escape and not be trapped by the caulk.

The caulking looks pretty sloppy at the window and sill intersection. Silicone is better than latex but I think a polyurethane caulk is superior in most applications.

The wood is never flush with the bottom of the capping as most window sills have slope and hence the reason that they supply sill angle with jobs that aren't getting capped.

Looks like it was cut a bit sloppy and they didn't tuck it into the accessory groove (along with the caulking issues that todd mentioned).

Should be a quick re-cap and caulk for seal.

Thank you all for the info. I do not know what type of caulk was used, but when I thought we were needing to do some "touch-up" caulking, I did buy 100% silicone. Good to know that's the right thing. Not sure if I saw polyurethane in the brown color at Lowes.

This part of the wrapping is actually some type of vinyl material. Some of the other wrapping is aluminum. Not sure why the different materials were used in different places around the various replaced windows.

I will make sure the guy puts wood to support the wrapping, That's definitely a big part of the issue with this window. Others haven't come apart like this, but I'm going to ask him to check that the wood is there to fully support the wrapping.

Windows on Washington Ltd, do you mean that the wrapping should some how "interlock" with the bottom of the window? That's part of what I've been wondering about.

What part is vinyl?

keep in mind silicone does not like to stick to it self once cured. The aluminum would not interlock at the sill but at the sides and the head. You can not see this groove since it is covered by the aluminum. This is not the root of your problem but more of nicer touch. The aluminum can not always fit into this groove but is good practice when it can. Hard to say what the exact cause of your problem is without pulling things apart. Caulking can hide a lot of sins, seeing a aluminum job before caulking usually tells all.

The whole piece that is covering the bottom "sill" that has separated from the window is vinyl, not metal.

Fooled me, you sure? That would be odd.

Well, I stand (sit?) corrected. It is metal, but very thin. It was hard to tell.

The window company came out yesterday, including the owner. The guy who did the wrapping added a piece of wood, put on a new piece of metal wrap, caulked. I think it will be good now. The other windows seem like they're OK, so we'll see. Thank you for all of the input. I appreciate it.

Sounds good

Sounds like they did a nice repair on that and it should hold up. Nice to see a company come out and honor their work. They sound like one of the good ones.