Hello,

I was just getting set to trim out my recently installed windows and noticed a small amount of water in both bottom corners. It has been cold where I am (sub 20 degree F), so it's possible that it is condensation, but I'm not sure.





The window has been installed for several months, but, until now, I've been concentrating on the exterior.
I believe I followed the spirit of the manufacturers (Pella) recommendations for installation (I didn't use Pella branded flashing, but, what I did use is at least as good). The sill is covered with Flex Wrap applied directly to the wood sill. The bottom flange is over the Flex Wrap. WRB is tucked in on the sides. Side and header flanges are covered with DuPont peel and stick flashing. WRB is over the header flashing and 'skip' taped.
I don't want to cover this up with trim until I'm confident that I'm not covering up a problem.

What are your suggestions for determining if it's condensation or if it's leaking? If it's leaking, what are my options for dealing with it? The exterior siding and window trim are installed and sealed, so I'd really be upset if I had to remove the window.
If it's condensation, how do I make sure it won't continue to have condensation behind the trim?

Thanks in advance.

 

Where's the condensation? Must not be very bad, can't even see it in the pictures. If it's on the glass and you can wipe it off with your fingers, that's fairly normal when you have low outside temps, and humidity over 25% inside the house.

If the condenastion is on your flex wrap, the only explanation for that is that you have air leakage that is letting cold air into the house. If you can feel any air movement through your spray foam on a windy day, then you don't have it insulated very well, and that's probably the source of the cold air that is causing the condensation.

A good way to search for drafty air leaks is to use a smoking incense stick (or fireworks punk) and hold it near the window on a windy day.

If your spray foam has holes in it, which I'm guessing it does, that is where your draft (and condensation) is coming from. You would be wise to dig it all out (use a keyhole / drywall saw) and replace it, doing a better job this time. Don't know what kind you used, but hopefully it was specifically for "windows and doors", and not the Great Stuff in the red can.

I also detest the practice of wrapping the housewrap into the rough opening (I refuse to do it) and I believe that is often a source of air leaks and condensation. If you insulate between the window and the housewrap, what keeps air from following the back of the housewrap right into the house? (Housewrap is hardly ever installed as a 100% tight air barrier where all the edges are sealed) I prefer to cut the housewrap at the exterior edge of the rough opening.

 

I agree with Brant on not including the house wrap inside the window frame. I have circled a potential area of air infiltration that can be alleviated if the wrap is cut away from the window flange and sticky tape applied to it, the OSB and flange together. Note, your sticky tape did not seal anything.



This video goes through the entire process of installing windows with flanges. I don't think it is in conflict with our site. Just for information. https://www.youtube.com/watch?v=YttTTi-hNZc

 

Thanks @XSleeper and @chandler,

I agree. I wasn't crazy about folding the WRB into the frame, but I was trying to comply with the manufacturer. I put in two other vinyl windows from a different manufacturer at the other end of house and did flash the sides to flange/slice of direct contact w/sheathing, edge of WRB. That has proven to be a much better seal--plus, I used sealant under the flange. Wish I had done that with the Pella.

The foam I used was 'Great Stuff' for Window and Door, but I believe it came in a blue can. When I trimmed the excess off (just after noticing the water), I was surprised at how many voids there were.

The moisture was in the corners. The pre-trimmed foam--which still had its 'skin'--was saturated--especially in the lower right corner shown in the second picture. The face of the vinyl window frame in the lower corners had visible water on them and I could squeeze water out of the (what was then) protruding foam.

Let's say I dig out all of the existing foam (as suggested by @XSleeper). What would you think if I fit the nozzle from a tube of OSI into the gap between the window and the 2x4 frame and spread a layer of sealant?. Then, after that sets up, I'd cover that with the spray foam.

Thanks again.

 

I don't think much of that idea but its ur baby. Generally when you foam a window you want to fill the space gradually... not all at once. I will blow the outer 1" first, then let it expand and start to set up before filling the space the rest of the way. Doing it in two passes allows you to fill the space about halfway, and the 2nd bead stops any drafts that the first pass may have left. Its also nice if you don't put so much in that you have to trim it... or at least there is less to trim.

 

Thanks again @XSleeper.
Yeah. As I thought about the OSI, I realized that the shims would interrupt any attempt to make a continuous seal. Plus it's pretty stinky and only supposed to be used on the exterior.

 

Thanks for the link @chandler.
I've watched a lot of Shannon's videos, but hadn't seen that one. He does a really nice job explaining what he's doing.

 

I use OSI quad max, but it has its own stainless steel applicator for the foam, which is pretty expensive, but it does get into that first inch space Brant was describing. Working your way out from there is pretty easy since the tip is so small, and you can adjust the rate of flow. You may be speaking of OSI in a tube, which wouldn't really work with the existing foam too well.