Sealing windows - butyl tape?

[Tim Good]

The windows on my deck saloon Seastream have been installed with sealant. Not surprisingly that has slowly degraded and now some leak.

Would I be better to remove them and use butyl tape instead? I recall someone suggested it a while ago and that’s what motorhome use on their windows.

 

[jamie N]

I've used CT1 without any problems, and would use it again.

 

[Minerva]

Can't help with your questions, but I like the double glazed window units! I presume they must really be of benefit in the colder months. Do you avoid / reduce condensation with these?

 

[Tim Good]

Can't help with your questions, but I like the double glazed window units! I presume they must really be of benefit in the colder months. Do you avoid / reduce condensation with these?

Yes indeed. But strangely they didn’t put double glazing in the sides. I’m unsure why.

 

[RunAgroundHard]

Tim,
Your frame style is similar to mine. I used Scapa 3507 bedding tape supplied by Hadlow Marine. The tape is applied to the frame and the frame secured to the coachroof. The tape is a foam tape, resilient with a high tenacity. It needs to be compressed by a minimum certain percentage of the thickness. Some of my frames had to be deflected round a slight curve, and tape compressed significantly, less away from the curve. All 13 frames on my boat have been in place with the tape for 7 years, bone dry. If I need to remove, nothing sticking to the hull. Very easy to apply to frame.

http://hadlowmarine.com/Pages/seals-bedding.html

I certainly recommend it for flange type frames that compress against a smooth gel coat surface.

Good luck with your solution.

Edit,
Having read your post again I think you mean the glass to frame seal. Mine were refurbished with Arbosil 1096 Black, but I am not certain about this. There is a Sikaflex equivalent.

 

[PetiteFleur]

Definitely use butyl tape and put stainless washers where all the mounting holes so the butyl tape doesn't get squeezed out. Any excess can be trimmed easily with a Stanley knife. Much better than sealant as much easier to clean off.

 

[dankilb]

I've used CT1 without any problems, and would use it again.

Far from ideal for glazing - not UV resistant, reacts with acrylic (most yacht windows - although these are clearly glass), strong adhesion can damage weaker frames upon removal, etc.

Great for most other things!

Can’t see any problem with OP using butyl tape with sealed glazing units and frames with plentiful fasteners (it’s only downside is no adhesive properties).

If you want a sealant-adhesive, you might want to look at Dow 791 (795 not available in UK) - there’s another recent thread on this.

 

[dankilb]

Real/recent reports from folk who’ve left CT1 in the sun (spoiler - it doesn’t like it!): Best UV resistant adhesive sealant?

Butyl is impervious obviously as it is a dedicated glazing sealant (before it became popular for marine deck fittings).

 

[Dellquay13]

I’ve used scapa tape from Hadlows on windows, hand rails and stanchion bases, all very easy, clean and watertight

 

[DangerousPirate]

Would I be better to remove them and use butyl tape instead

Short answer: Yes.
Slightly longer answer: Yeeeees.

 

[kacecar]

Another answer, but longer still.

The photos seem to show the sealant that holds the glass in the frame breaking up rather than a problem with the seal between the window frame to the coachroof. This latter joint is the one that might benefit from the use of some form of butyl tape, or indeed the Scapa bedding tape referred to by RunAgroundHard in post 5, but the former joint won't.

If, as it would seem, the problem is with the sealant that holds the glass in the frame, I believe it is possible to trim that back and replace it with a fresh bead of sealant (such as the Arbosil stuff that RunAgroundHard also mentions). I hope so - it's what I'm about to do to the windows on my own boat.

 

[neilf39]

I found butyl tape too thick to be able to seat the frame and do up the short interscrews so used butyl mastic (arbomast) instead. Initially more flexible and squishy.

 

[Stemar]

I found butyl tape too thick to be able to seat the frame and do up the short interscrews so used butyl mastic (arbomast) instead. Initially more flexible and squishy.

I got round that by using a few longer set screws with ordinary nuts to pull the frame in, then using the right ones. A bit of butyl around the neck of the screw ensures a good seal where the longer ones were.