butyl tape window leak

RVcircus wrote:
what if you make a shim using the inside of the window trim and or the window opening as a template? I'm thinking butyl tape will be a better deal long term than just ProFlex assuming you can compress it.

I ran a strip of blue tape across the top seam, but still had a leak last fall. So I taped the window up tight with plastic for the winter and it was dry. The forecast looks dry so I removed it.


It took 15 minutes of prying because the butyl was still nice and soft. No signs of water streaking or leaking by except on the sill and interior paneling damage. The window weep holes were clean.

I hope the window itself is not leaking, but the more I look and think about it I fear it is. Is there a window seal rejuvenating liquid? lol

The only thing I can come up with is to reinstall the window and then if there's still a leak, I know it's the window seals? Or did I prove its the window itself, when it continued to leak with tape across the top?


Second, the trim ring having that Z shape isn't helping. You can see the gasket I used to shim it and it seemed to work well. But you can also see I would be better of with a flat trim ring with how far the window comes into the frame with no butyl.

Anyway, I think I will remove the gasket spacer and flip the trim ring with the outside facing in. It will be ugly, but so am I.

And I think I will use only one layer of butyl and trim it back enough space for a tiny bead of proflex.. Sound like a plan?


Or do I need new window seals or a new window? Im tired of this.. How long do window seals typically last?


Thanks everyone!

what if you make a shim using the inside of the window trim and or the window opening as a template? I'm thinking butyl tape will be a better deal long term than just ProFlex assuming you can compress it.

beemerphile1 wrote:
You used butyl tape or putty tape? There is a big difference in both price and performance.

It's butyl. I still have some of the same tape left over, and its still soft after three years.

I just need to rejuvenate the butyl around the window and draw it in tighter.

RVcircus wrote:
(I give it a day or so before trimming) and then seal with a bead of ProFlex to be safe.

I like the proflex too and used it on my roof with good results. Im tempted to remove the window and redo with proflex alone. But the shimming required has me seconded guessing that plan.

When I do my windows I look for the tape to compress and squeeze all the way around. I'd remove the window and add a 3rd layer of tape or shim the inside to allow you to tighten. After I install I trim any butyl tape that squeezes past the edge of the frame (I give it a day or so before trimming) and then seal with a bead of ProFlex to be safe.

You used butyl tape or putty tape? There is a big difference in both price and performance.

Chris Bryant wrote:
You should not have to double up the butyl on a smooth skin, so I would say the you need to shim the trim ring inside to make it shug.

Bingo! The trim ring is tight, but doesn't draw the window tight.

Any suggestions on a spacer? Maybe some thick rubber gasket cut narrow?

And is kerosene best for a clean up and soften?

I'm concerned, because I used this butyl in other spots on the TH But none I couldn't tighten like ALL the windows. jc

You should not have to double up the butyl on a smooth skin, so I would say the you need to shim the trim ring inside to make it shug.

Since the tape is pliable and the window can move (slightly) while in transit, it might be a good idea to tighten the mounting screws every so often. A bead of polymer sealant around the window edge wouldn't hurt, either.

are sure it is the window and not the seam above the window that is leaking?