Butyl tape lesson needed

[Unclematt]

I am installing four new windows in my salon using butyl tape. I have watched you tube video's and last night I tried installing one. What is the best way to put it on and make it flat and be sure it seals. I will be removing my freshly installed window and try again tomorrow. All advice is appreciated.

 

[tiltrider1]

Butyl tape is pretty easy and forgiving. If you use to little you won’t get a good seal and you will need to remove the window and try again. To much butyl tape and it will ooze out for a year, not the worst problem.

If all parts mate up well then one layer of butyl tape will do the job. If you are installing flat windows on a curved surface it could take 2 or 3 layers of butyl tape at the ends to make a good seal.

For me the real trick is to tighten the screws a few revolutions at a time and then move on to the next one. This gives the butyl a chance to ooze into all the right places. Better to come back and re-tighten each screw many times then over tighten and damage something.

 

[Comodave]

Absolutely you have to tighten it slowly over at least 3 days if the temperatures are reasonable, longer if it is cooler. Marinehowto.com has some DIY with butyl tape articles. I use his butyl in sealing a lot of things.

 

[Bacchus]

Don't forget to chamfer all holes so the tape is forced around fasteners. Also a small piece rolled round and placed under flat / oval head bolts / screws ensure a seal at the outside.

 

[psneeld]

I DON'T make it flat...I usually fold it in half or pinch it up to make sure it fills any gap.


I then screw it down snug, not necessarily finished tight, but good enough to get squeeze out.


Then over the next few day keep tightening...then check again several weeks and months later.

 

[Unclematt]

Do you use it at its full thickness? In one video the guy pulled and rolled it to make it thinner then worked it to flatten it out on the window flange. I tried doing it their way and the outside flange is now out 1/8" the thickness of the hand flattened butyl tape. I have not tried to pull it in with the screws in case I need to remove it. I am installing windows made by Motion Industries which have self tapping screws on the inside using a trim ring. Lots of care when tightening them I would hate to strip any.

 

[psneeld]

I use enough tape to make sure it fills the gap, pinching or rolling if it seems like not enough single thickness...a second layer could be used but often it would be way too much.


Squeeze out just like regular caulk is the tell tale...if it doesn't, pull up and add some...my windows were the same with the interior clamp ring, so yes firm but careful tightening is the way to go.

 

[EricH]

A glass guy told me to spray it with water or Windex after applying it to the cabin just before you put the window in. Gives you a little time to reposition.

 

[Trawler_traveler]

Be aware that in hot sun climates the butyl can 'melt' and actually drip out. That happened to us both with the black butyl we got with our beautiful NFM SS ports and with a gray butyl tape we got from some RV place.

I don't think it actually caused any leaks but it made a bit of a mess.

It was a problem in Mexico going south on the Pacific side.

 

[Comodave]

Do you use it at its full thickness? In one video the guy pulled and rolled it to make it thinner then worked it to flatten it out on the window flange. I tried doing it their way and the outside flange is now out 1/8" the thickness of the hand flattened butyl tape. I have not tried to pull it in with the screws in case I need to remove it. I am installing windows made by Motion Industries which have self tapping screws on the inside using a trim ring. Lots of care when tightening them I would hate to strip any.

Yes, you can work it out thinner but the caution is not to make it too thin so it doesn’t seal properly. By all means do not over tighten it all at once. Just start with a bit of compression and each day snug it a bit more. Even if it takes 7 or 8 days to secure it, it is better than stripping out the threads. With through bolts and nuts I usually do 3 days of tightening, but with tapped screws I would take a lot longer to tighten it up. Once you strip it out you can’t back it off and have it work ok...

 

[Unclematt]

Great tip wetting it to allow for adjusting. The one I set in the other night is not square and is to far forward for the ring to fit luckily I only have a thinner layer of tape so I will take it back out and reinstall. This is my first foray into installing windows using tape and the advice is greatly appreciated. Thank You

 

[psneeld]

So far after a summer in Florida, none of the 3 different tapes I have used have "melted", really haven't seen anything unusual with the 3-7 year old tape.


I haven't experienced that issue and there are many an RV using it on windows that are kept down here in central Florida. It gets plenty hot and squeezes out more....maybe just not tropical hot enough.


Maybe be careful where or what tape you buy if you can even tell a difference....I don't....


Here is what Dicor claims for their butyl tape


Appearance: Grey, extruded butyl sealant tape.
Temperatures: Application: 30°F – 110° F Operating limits: -20°F – 275° F.
Low Temperature Flexibility: No cracking, no adhesion loss at -20°F.

 

[Stout]

Butyl Tape install

Check out this web page for excellent informative instructions:

https://marinehowto.com/bed-it-tape/

 

[Unclematt]

Here is the finished picture, I am very pleased. All your collective bits of advice helped make the job quite easy. Thanks

 

[Comodave]

Glad it worked out for you, another butyl expert on board now.

 

[C lectric]

One trick I have used although no help to you for this project is to use clamps and scraps of wood for the compression of the tape. I also cut it , not applying the full 1/2" width,

I still go clamping lightly but it has worked well on my door frame trim, darn Teak, and my portlights. That way the screws have very little to do with compressing the tape.
They just get to secure it all once done.
THis own't work in all situations of course but nonetheless I have saved my self a bunch of effort and time with the clamp and clamping blocks/strips.


Before I forget, Nicely done.

 

[trawlercap]

Easily the best write up I've seen (and now try to follow) on bedding fittings:

https://marinehowto.com/bed-it-tape/

 

[Swa]

Great advise here and thanks for the link to "How to Marine" The only problem is the more I read the bigger my to do list gets.

 

[sbman]

One thing I've found that helps is to make up some 'guide screws'. I get a couple of extra long screw that match the holes in the frame/boat, cut the heads off with an angle grinder, and then use vice grips to put two of these into two holes in the frame on the boat, one on each side.

Then after I've applied the butyl tape to the window, I can place the window onto the 'guide screws' and slide it into place with perfect alignment, put some of the other screws in and then replace the guides with the proper screws. This eliminates the chance of the butyl getting pushed/pulled out of place when trying to reposition it for screw alignment, because it's already aligned at first contact.

 

[grumpyfnq]

Maybe a bit left field but I have used butyl on a number of sealing jobs and found that in hot climates, it just continues to squeeze out every time it gets very hot. Suggestion from somewhere was to set it with some thin rubber string (Oring make up cord) cut into short pieces that are in middle of the butyl tape. Gives a guaranteed thickness of butyl, can't squeeze up until thickness is almost nothing, a definite stop when doing up and some spring to hold fasteners tensioned. Found it worked like a dream.
Lots of other good suggestions from others too, wetting, guide fasteners, sealing heads of fasteners.

 

[Frosty]

... set it with some thin rubber string (Oring make up cord) cut into short pieces that are in middle of the butyl tape.

That's an interesting concept. Kind of the reverse of the indented groove you see around some better-quality stanchion bases or similar intended to trap a ring of sealant.

Can you say what size/part number you used?

Presuming you have chamfered holes (to trap rings of sealant), do you see an issue with just tightening "all the way" so no more oozes out (but the material would stay in the chamfers)?

 

[grumpyfnq]

Sealing Windows

The theory I have followed is that you need a thickness of butyl to accommodate the differential expansion and contraction between the glass and the frame. When you keep tightening until nothing more squeezes out, you have points where both are in contact and nothing to accommodate any differential temperature movement or flex in structure in rough weather and eventually that will leak.

I just used some o ring cord from an o ring supplier that you use to make o rings in field, about 2-3 mm dia from memory but you could easily just get some larger o rings of a suitable diameter cord such as used in deck plates or water inlet filters and chop them into short pieces maybe 5 mm long. From memory we spaced them about every 200 - 250 mm near but not at fasteners orientated along tape direction. I think the idea came from a utube from NZ on fitting boat windows, not sure.

I think the groove in stanchion bases etc does same thing where you need a face to face contact to carry load and a thickness of butyl to seal and accommodate movement between the faces.

I do not think relying on a chamfer around the fasteners will get you there with windows. The fasteners would be OK but the space between the fasteners where some of it has negligible thickness of butyl will probably leak.

Just another way to approach it but retains the main thing I like about butyl in that it stays soft and accommodates differential movement.

Keeping water out longer term is a challenge in my experience and there isn't any one foolproof 100% answer.

 

[Frosty]

Thanks for adding the detail. I agree that some things present more of a challenge (say, a large port or window vs. something smaller you can really clamp down on).

I'm going to keep your idea in mind.

 

[C lectric]

O ring bulk strip is also available in 1/16 diam.

Unless you go to an actual seal specialty shop you will likely have to order and wait for it for a few days.

The strip is a good idea which I may use in the near future.

T.Y.

 

[FlyWright]

There's butyl tape and then there's butyl tape. I've had great success using Rod/CMS/Compass Marine's butyl tape. It's thicker in dimension and density than most run of the mill RV butyl tapes. I'm in the CA Delta with 100+*F summers and so far, no runs, no drips and no errors.

 

[Frosty]

There's butyl tape and then there's butyl tape. I've had great success using Rod/CMS/Compass Marine's butyl tape.

I'm with you on that.

I had actually typed a few more paragraphs on my last post, describing how I had tested a number of butyl tapes and Compass Marine's "Bed-it" (aka marinehowto.com) was noticeably better than the others (it was the only one with the amazing elasticity of an old, old roll of "the good stuff" I had left on the shelf from days gone by - which was great until it ran out ).

But then I decided it sounded like an advertisement so I deleted that part (tho I have no affiliation other than happy customer.)

 

[sbu22]

There's butyl tape and then there's butyl tape. I've had great success using Rod/CMS/Compass Marine's butyl tape. It's thicker in dimension and density than most run of the mill RV butyl tapes. I'm in the CA Delta with 100+*F summers and so far, no runs, no drips and no errors.

X2. Never a problem with the Compass Marine butyl tape. Good stuff. I use it for windows, bedding deck fittings, etc. etc. I was initially confused by Compass' apparent name change to marinehowto.com.