Replies

1. 
   patwig | Oct 08, 2002 08:57am | #1

   Yes.

   Strips of adhesive-backed-gummy-black-rubbery stuff, placed just-so. over the flange and to the sheathing in behind the house wrap across the window top. Over the wrap otherwise.

   No caulk at this stage.

   I vote yes,

   Patwig

2. 
   SMARTSPEC | Oct 08, 2002 09:36am | #2

   Aye to the water shield and if you're not, Aye to the caulk. Keeps it stuck to the wall after the nails rot off.

   sometimes board sometimes knot

3. 
   Piffin | Oct 09, 2002 05:24am | #3

   First off, remember that this is not an item thatis worth losing a friendship over. Interesting that even menufacturers are divided isn't it?

   I never thought about it before, honestly, but now that my synapses are all a-twitter on the concept, I might start to caulk behind the top and side flanges before putting the window in and the Vycor on over. Lots of windows have flanges that I don't trust much for waterproofing, especially at corners anyway so I think the Vycor is especially important, more so than this caulk idea. Seems like caulk is more of insurance against sloppy workmanship on the entire envelope, calculated by the manufacturers callback crews to eliminate complaints for a few years. Talk to any service rep from any window place and he'll tell you that somewhers arounf nine times out of eight, the reason a window is leaking is that the yahoo who put it in and wrapped the house didn't keep the laps facing downhill in the housewrap or tarpaper.

   .

   Excellence is its own reward!

1. 
   rickchem | Oct 09, 2002 06:42am | #4

   No friendship lost - just a good discussion!  Sort of decided it depended on the situation - makes no point to back caulk the flange to the sheathing, if installing windows before tarpaper, because if the water reaches the caulk at that point it has logically already reached the sheathing and gotten behind the tarpaper, and all is rotten anyway.  But, if wrap is applied first, makes sense to me to caulk the flange to the wrap, because any water repelled by the caulk simply sits or runs on the wrap (with the top flange tucked into a slit in the wrap of course!).  Does that seem reasonable??

1. 
   Piffin | Oct 09, 2002 07:07am | #5

   I never have or probably will put windows in beforrre wrap or paper, but if I did, I would definitly use caulk there. Reasonning - Yes, you might be wetting the sheathing and it will have a good chance of rotting someday sooner or later. But by putting the bead of caulk there, you have possibly prevented the water from entering the window frame box area where it might find a way to enter the finished living space, agravating the snot out of the owners and painters.

   It could be argued that it is good to let it come on in, and not be trapped in the wall or kick back out for two reasons. One is that you want to know if a wall has water penetration as early as possible to be able to fix it instead of hiding from it or hiding it from you. The other is... Oh shoot, I forgot! oh yeah - you want the water to run instead of being trapped so mold and rot don't happen..

   Excellence is its own reward!

1. 
   rickchem | Oct 09, 2002 10:41pm | #7

   Piffin-

   From your earlier post, does that mean that you did not back caulk before??

   Place I'm working on had no wrap, no window tape, no back caulk, just wooden double-hungs nailed through brickmold.  No water intrusion or rot (other than the brickmold rotting away), although the double pane seals failed.  And aluminum siding too.  I'm wondering if aluminum is less porous than vinyl siding (as a system, not the material)?

   Its amazing this house had no damage except trim, whereas newer houses seem to have a ton of problems.  'Course, I have only gotten to the windows underneath the soffit on the second story . . . first story may be a lot different!

1. 
   Piffin | Oct 10, 2002 02:47am | #8

   Right, I never heard of or considered back caulking before.

   With wood windows and brickmold, I put a metal flashing over the header piece.

   Are you just replacing trims or doing total window replacement? Fypon has a foam trim profile in a brickmold style..

   Excellence is its own reward!

2. 
   rickchem | Oct 10, 2002 06:26pm | #10

   Piffin-

   I'm ripping out the whole window.  I started doing just the trims and a few windows (double units, unshimmed in center leading to sag), but was able to convince them that since they were getting new siding, and the rest of the windows have clouded up due to seal failure, it was best to just replace them all, since sash or glass replacement would end up being near the cost of a new, much better window.  They are stuck on vinyl siding, so I have been trying to find window casing to replicate the brickmold trim they like.  Heartland siding has window j/casing that has a brickmold profile, but the siding guy or local distributors don't carry them . . .  

       I've used the vinyl brickmold trim before, replacing a single window on the same house, probably similar to fypon.

3. 
   bd342 | Oct 10, 2002 04:02am | #9

   highly recommend backcaulkling with a good quality polyurethane sealant.

   Its cheap insurance if your seal tape gets damaged. Your observation about the permeability of the vinyl siding system being more prone to water intrusion sure matches what I've seen as well.

4. 
   JohnSprung | Oct 09, 2002 10:17pm | #6

   Perhaps it depends on how the water arrives.  For ordinary gentle rain, I don't think it matters.  If you typically have 40 MPH winds driving the rain horizontally, the additional resistance to air movement could be helpful.

   -- J.S.

5. 
   HammskiJr | Oct 10, 2002 09:18pm | #11

   I've been involved in many major facade repair jobs, both residential and commercial ... the 1st rule is to be aware that caulking/sealant is a last line of defense.  Proper detailing should assume water will get behind the siding and your next line of defense is to shed it away mechanically (ie; with wrap, flashing, etc.) I vote no to the caulk and yes for the extra lap at top and sides.  Not at the bottom, though, so whatever gets in can find a way out.

1. 
   Piffin | Oct 11, 2002 03:12am | #12

   Definitely not caulk to count on, just for the insurance..

   Excellence is its own reward!

1. 
   HammskiJr | Oct 14, 2002 06:20pm | #13

   I agree - Last Line of Defense!!