Caulking, Butyl Tape, Window Reseal

[TerryH]

Below are my recommendations for removal, reinstalling and resealing of windows. They have worked for me for many years in RV, Marine. Residential and Commercial applications.


Materials used are
Painter’s Masking Tape
Electrical Tape
Tremco POLYshim Butyl Tape
QUALITY Polyurethane Caulking

Removal: Highly recommend an Olfa Utility Knife (box cutter) with the segregated snap off blades with only name brand blades - no cheap Chinese crap.
Also a couple of pry bar/scrapers - I only use this

https://www.kmstools.com/richard-10-pry-bar-and-scraper-95114

Pry bar, knife and blades are readily available at hardware/big box stores.
The butyl tape should be available from any reasonable size glass shop in 40’ rolls.
Caulking - I would avoid big box stores in lieu of a sealant supplier or a roofing material supplier. You are buying quality caulking, not a BBQ or chandelier.

You can and should sharpen the flat end of the pry bar on a bench grinder. Do one side only, similar to sharpening a wood chisel. Draw both sides over a piece of sand paper after grinding to remove burrs. This will greatly assist to avoid gouging your exterior wall.

*Suggestion - start with your smallest window first - the one above the galley sink?*

Window Removal:
Remove the trim screws and trim - good time to paint it if you wish.
*Suggestion - should the trim screws be self drilling (not tapping) replace them. Reinstalling self drillers commonly destroys the threads in the window frame screw chase.*

Check the gap all around the window frame to body at the interior. For reinstallation you want the frame centred vertically and horizontally in the opening.
For vertical centring you will need two shim blocks for the bottom only, about 6” in from the sides. Thickness is ½ the top and bottom gap.
For horizontal centring you will need one each side about 1/3 up from the bottom. Side shims should be very slightly slack to enable installation.
Shims should span the wall insulation only - not the interior or exterior skin - to prevent obstructing the frame and trim and to ensure they do not contact the butyl tape - see diagram.

Starting at the top at the beginning of the radius use the knife carefully and with eye protection - the blade can break - slice thru the butyl with repeated strokes. You won’t get thru with one slice. Do this for about 8 inches, then use the hook end of one bar to gently pry the frame from the body. Masking tape on the body will help prevent damage. Once the frame starts coming free use the second bar in conjunction with the first to continue on, all the while slicing thru the tape. If you find the cut tape is adhering to itself spray it with water or glass cleaner. Continue on until the frame is out.
You can use the flat end of the scraper to remove the butyl from both the body (carefully) and frame. If there is a fair amount of the old butyl left on either you can cut 6” of the new, roll it in a ball and then roll it on the old to remove it. Sometimes helps.
Small, thin amounts of old butyl left behind are ok - it does adhere to itself.
*Should there be ANY silicone present from previous attempts to seal you will have to remove it.*

Install the shims as above - masking tape will hold them well enough.

If the gap between the frame and opening was 1/8 or less you can apply the new butyl to the frame - preferred.
If a larger gap apply it to the body.
Intention here is to ensure the shim portion of the butyl tape is between the frame and body, adequate contact of the tape to both, and to provide a void between the outer edge of the frame and body for the caulking to fill and do the job you bought it for.
Regardless, use one piece of butyl tape per frame. Start at the bottom centre and continue on, leaving the protective paper in place. At the radius corners you will have to cut the paper in place to allow the tape to form a curve. The tape will curve but the paper won’t. I use my thumb nail to tear the paper as I make the radius. When you get back to the starting point cut the tape slightly long and meld the joint together. If you are doing all of your windows you will have roll ends left over. Avoid the temptation to piece them together.

At this point I would dry fit the window and have someone hold it while you go inside and check the gap, etc. to ensure all is fine. If good, remove the paper from the butyl and go for it. Bottom first, top tilted out until properly positioned and centred. Two people advised for final positioning.
*Suggestion - if you spray the bottom and a couple of inches up the sides of the butyl with water it will aid you in positioning the frame. Excess will squeeze out and dry.*
*Suggestion - if you have access to suction cups they will make the reinstallation much easier. Also handy for moving appliances. Just be careful of your toes - they are not infallible.*

Interior trim:
Screw in top and bottom of each end of each radii and then centre top, bottom and sides. After, follow standard torque procedures, but do not over tighten. Go over again until hand snug.
If you can, leave it as such until the next day, then snug up again. The shim in the tape will prevent the tape from over compressing. Check the operation of the sliding/opening portion of the window to ensure you haven’t warped the frame.

Caulking
Masking:
This step will provide both an effective seal and a very aesthetically pleasing finished product. Your windows are very visible to you and others.
Based on one piece frames - usually black with radius corners, use electrical tape. Masking tape will not form to a radius.
    Body - start where you are comfortable, laying the tape 1/8” away from the frame. As much as possible avoid stretching the tape to avoid puckering. Rub it well to achieve full contact. At the radii you will have to stretch it somewhat. When you join with the starting point run the tape away from the frame for a few inches, cut and fold over. This will aid when removing the tape.
   Window frame - as above, but run the tape to the outer edge - no further - of the frame. When meeting the starting point run the tape towards the glass and fold over. 

Caulking:
*From this point on you are committed. You must keep going until finished. No beer breaks.*
Cut the tip of the tube approx. 60deg. with the open end slightly wider than the frame to body void. Pump out a few inches on a rag to clear any debris and air, and also to give you a sense of the viscosity and speed/trigger pressure relationship. Hold the gun about 45deg. from the void. If you are caulking downwards raise the back of the gun a few inches, if upwards lower it.
*Go slow until you are confident. The entire point here is to fill the void, NOT to put on a skim coat.*
Run the caulking ahead of the tip - you are pushing it into the void - not pulling it. You should at all times have a ’ball’ of caulking ahead of the tip. The trailing end of the tip will force it in further. At the same time you are forcing air out of the void ahead of the caulking. Trapped air will create a bubble that will cause future headaches.
The ideal is to caulk the entire window in one pass, but that is seldom achieved. If you stop, go back a few inches and then continue on.

Tooling/clean up:
*Should you not tool the caulking you will have thrown away your money and wasted a lot of time.*
I use my bare finger for tooling, but then I am old enough that I can ignore the warnings. I get tired of reading on coffee cups “caution - contents hot!”  Your choice.
Have paper towels, garbage bags and glass cleaner handy.
Run the pad of your dry finger over the caulking bead with considerable pressure. You are forcing the caulking further  into the void and removing excess caulk. You will have to stop frequently to clean your finger. You also want a minimum of excess left on the tape to avoid a mess to try to clean later.

Now do the same thing again, less pressure, one pass if possible to prevent a stop/finish visible ridge. While doing this pay attention to the tape to window and tape to body edge of the caulking. Ideally you want as minimal a ridge as possible.

Now spray the bead with glass cleaner and using your clean finger pad run over the entire bead with light pressure, short and quick strokes. This is close to the finished bead, so carefully check the appearance.

Almost done. Remove the tape - here is where you will appreciate the folded over tab. Pull the tape off at a sharp angle to itself to prevent stretching and slightly towards the caulking bead. This will help lay any tape ridge feathers of caulking back into the caulk.
*Suggestion - have a garbage bag ready for the tape, and fold the tape into itself as you remove it to keep it manageable.*

If required, dependent on how it looks and what you want to achieve, you can carefully tool further to your desired finish.
If so, use the glass cleaner liberally with very soft and quick finger strokes.

FYI  the reason for the shim tape is to provide a controlled void for the caulking. It further works as a back stop for the caulking and, to an extent provides a bond breaker to prevent three sided adhesion.
Caulk is meant to seal a void - not to be a skim coat over surfaces that have a different expansion/contraction factor between themselves and the caulk. Guess which one will fail? The worse thing I see is where someone has slathered on a 4” wide bead with a putty knife to seal a roof vent. Entirely counter productive.

Your primary seal is the correctly applied caulking.
The shim in the butyl tape maintains the very necessary void.
The butyl tape is the secondary seal.

The most common failures of caulking are (not in order)
Poor prep
Poor application
Lack of tooling
Three sided adhesion
Air bubbles

My personal preferences for polyurethane caulking are NP-1 and Sika.
Another member here, WrigleysBraveWin, suggested the following product. I have yet to try it, but from what I have read it sounds good. Correspondence with the manufacturer was very satisfactory:

ChemLink M-1
My email to Chemlink, rberthiaume :
         Hello Mr. Berthiaume.
I am interested in the above as a sealant and occasionally adhesive in RV use. Substrates would generally be wood, aluminum and fibreglass or a composite of each. I realize the importance of knowing the composition of any paint/coating that has been applied to the substrate.
My queries are:
-- is a silyl terminated polyether compatible with, or will it react adversely with, or will it bond to butyl glazing tape with an internal EPDM shim such as made by Tremco?
-- Would the butyl tape serve as a bond breaker to prevent 3 sided adhesion?
-- Will M-1 bond and adhere to itself in a repair situation where a section of the cured M-1 has to be cut out and fresh reapplied?
In most cases the tape would be used to create a compression controlled void that would be filled with the M-1. Generally, particularly with RV owners, the standard is to continually apply sealants as a lap seal and hope for the best. I and others on various RV forums are trying to inform owners that caulking is a void filler, not applied with a putty knife.
Based on research to date I am impressed with M-1.
Any advice would be greatly appreciated by myself and others.
Info re Tremco Poly Shim Glazing Tape, should it help:
Thank you for any assistance you can provide.
Regards
Terence Haeber

Their reply:

On Wed, Aug 2, 2017 at 12:55 PM, <rberthiaume@chemlink.com> wrote:
Terence,
Our Plyether products are solvent free and should not have an adverse effect on the glazing tape or Tremco product. or EDPM Shim.
The glazing tape will not be the best choice as a bond breaker if dynamic joint movement is a requirement. Bond breaker tape would be better. M1 will ahere to itself when abraded and cleaned of with alcohol before the new is applied.

Rick

I realize that this method is time consuming, but if you wish a visually pleasing and one-time effective window seal I can attest that it works. Carefully done it is likely you will be the only one who realizes your windows have in fact been caulked.

The above was written for a coach that has one piece frames with radius corners. There would be a few differences for those with 4 piece frames with mitred square corners.

The same basic procedure works for a roof vent, stink pipe,  roof rack stanchions etc., with, of course modifications to suit the particular circumstances.

[TerryH]

Having difficulty inserting a drawing. I'll keep trying.

[khantroll]

Terry, this is awesome. Thank you!

[WrigleysBraveWin]

Terry thanks for the info .... BTW M-1 is a serious Sealant and preferred over NP1

[Rickf1985]

Outstanding write up. It tells me that the way I did mine with the premium butyl I bought means I will be doing it again in the not so distant future but I already knew that. Now I know how to go about it the next time. I wish I could get the M1 here but from what I can see I can only get it from the West coast at a cost of 12.00 a tube.................................. plus 14.00 a tube for shipping!!!!!!!!!!

[TerryH]

Thank you all.
Wrigleys, when I wrote this I could not recall who recommended the Chemlink. I've edited my post to give you the credit.
I've yet to try it, but on paper it would seem to be the go to product for our needs.
Now if I could get this damn drawing to load........

[WrigleysBraveWin]

Thank you all.
Wrigleys, when I wrote this I could not recall who recommended the Chemlink. I've edited my post to give you the credit.
I've yet to try it, but on paper it would seem to be the go to product for our needs.
Now if I could get this damn drawing to load........

That’s a heck of a lot of info you posted -  much appreciated .....

Let me know when I can bring my rig over!

[HandyDan]

As one that is going to be doing this in the near future, I really appreciate the write up.  My windows have sucked the seals between the double panes into the interior of the window.  That is something I have to address.  There is a company in Arkansas that specializes in this repair but they are pricey and I would have to get there.  I would like to try to tackle it myself.  There are youtube videos that show how and sell the needed supplies.

[WrigleysBraveWin]

As one that is going to be doing this in the near future, I really appreciate the write up.  My windows have sucked the seals between the double panes into the interior of the window.  That is something I have to address.  There is a company in Arkansas that specializes in this repair but they are pricey and I would have to get there.  I would like to try to tackle it myself.  There are youtube videos that show how and sell the needed supplies.

Where at in Arkansas?

[khantroll]

Hi Dan,


Do you have links to videos?

[Jonbbrew]

 I dont see anything