# Proper way to repair cracking caulk on exterior windows



## RustNeverSleeps (Sep 26, 2015)

*Photo #1* shows some cracks that are more or less all along the vertical sides. Based on prior experience with other windows, I expect the gap between the window and brick to be quite narrow, certainly not enough to insert any foam backer rod. In which case I ask is it best to treat the existing caulk as backer and simply re-caulk over the top of it? Or is it better to remove this old caulk before applying new caulk? 

For a slightly different take I noticed that nearly every window had some cracked caulking near the bottom of the window sill. I suspect this is due to more sun and/or more water exposure but otherwise it is a mystery. In these cases, I have been removing the old caulk near bottom 6-12 inches of window and applying new caulk. But I am less than halfway done, so any thoughts on proper treatment are welcomed. Initially I thought I should treat any cracked caulk as a warning sign to remove all caulk from top to bottom. But after seeing how difficult it is to remove makes me realize it must be in better shape than I first imagined. Hence a switch in tactics to only repair what is clearly damaged or likely needing attention in near future. *Photo #2* is an example, where only a course or two of bricks has any cracking caulk issues.

Finally there are some small pin holes like shown *photo #3*. I believe I can safely re-caulk over these. This pin hole condition was not a common problem, the cracking is much more prevalent issue seen on almost every window in varying degrees.


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## RustNeverSleeps (Sep 26, 2015)

In short I am trying to understand the proper way to repair aging caulk before repainting.


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## joecaption (Nov 30, 2011)

I just remove what's loose.
Fill any large gaps with foam cording.
Your going to get all kinds of ansewers on what to use for caulking.
I use DAP 230.
http://www.homedepot.com/p/DAP-Dynaflex-230-10-1-oz-Premium-Indoor-Outdoor-Sealant-18275/100035980
Paintable, easy to tool, water clean up.
Any solvent based caulking will be a night mare to clean up on that brick.
The trick is to only use a small amount.
I apply it, wipe with my finger, then use a really wet stiff sponge with the scotch brite pad on the back to wipe it off and flush out any access on the brick.
Going to also need a stiff 1" wide putty knife to clean the excess out those mortar joints. 
Once finished rince off any white residue from the run off by misting with a hose.
It takes me less then 1/2 hour from start to finish on a window that size.


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## Nestor_Kelebay (Jun 17, 2008)

You're discovering what most of us already know, which is that the toughest part of maintaining caulk is removing the old caulk.

I would encourage you to remove all your old caulk and replace it with Kop-R-Lastic caulk, even if you have to mail order the Kop-R-Lastic. Alternatively, if you go to your local Home Depot and find Stone Mason Gutter and Siding Sealant in the aisle where they sell evestroughs, then that's the same product only in a different package. The only difference is that Kop-R-Lastic comes in 8 colours whereas Stone Mason Gutter and Siding Sealant only comes in clear and white.

The Henry Company of the US purchased the U. S. E. Hickson Company here in Canada which used to make Kop-R-Lastic under license from the Koppers Company of Australia. My understanding is that both the Henry Company and U. S. E. Hickson here in Canada are both making a product called "Stone Guard Gutter and Siding Sealant" which is basically Kop-R-Lastic caulk in a different tube. Home Depot (in Canada at least) sells Stone Mason Gutter and Siding Sealant in the same aisle where they sell evestroughs; NOT in the caulking aisle.

I have 66 windows in my apartment block, and I won't use anything but Kop-R-Lastic on them. That's because Kop-R-Lastic is a synthetic rubber who's cohesive strength is even greater than it's adhesive strength. That means it sticks to itself better than it sticks to other common construction materials. And, that's important because if you ever want to remove Kop-R-Lastic, you just get one end of it started and it pulls off cleanly just like a rubber rope. That makes removing the stuff a breeze. However, it has more then enough adhesive strength to stay in place and you have to pull fairly hard to remove the stuff. But, you don't have to be concerned that the stuff will start to come off on it's own.

Kop-R-Lastic is easily tooled with a soapy finger and it's paintable. It's got about the same elasticity as silicone, but it pulls off cleanly and doesn't leave any sort of residue on the surface it was stuck to. While I've only replaced a little bit of the Kop-R-Lastic on my building only to replace it. I've never seen Kop-R-Lastic crack as seen in your photos, and I expect that's because of both it's excellent adhesion and high elasticity. I don't know of any other caulk which has the same properties as Kop-R-Lastic, but the reason why I use it is because it works very well and allows for fast easy removal if and when you ever might need to remove the stuff. That's very much different than other caulk which are like fighting with a bear to remove.

All of the window companies here in Winnipeg use Kop-R-Lastic to caulk around their new window and door installations.


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## Nestor_Kelebay (Jun 17, 2008)

That looks like acrylic caulk in your pictures. I would remove what I can with a hooked blade utility knife and then see if acetone dissolves the rest. But, be warned, acetone will dissolve latex paint. I've used acetone on PVC windows without any problems with the PVC melting.


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## RustNeverSleeps (Sep 26, 2015)

Good feedback, I wished I had asked this question earlier, before I got partially started on the task. 


joecaption said:


> I just remove what's loose.
> Fill any large gaps with foam cording.
> Your going to get all kinds of ansewers on what to use for caulking.
> I use DAP 230.
> ...


Great tip about using a stiff sponge with scotch brite pad for wiping off excess. That never occurred to me, even after making a few mistakes/drips that needed wiping down with a wet cloth, which would have been much easier to clean using something with more heft.

After applying caulk to one or two windows and smoothing with only a wet finger, I found that it left a line of thin caulk that was a little too wide and ragged for best looks. (I was partly replicating prior caulking jobs, where some were more ragged than others so I did not put much forethought into it). The most recent window was done after first applying masking tape to get a sharper line. It looked much better and gave me more confidence as I am learning how to apply. But even then it is tricky for a newbie to lay down the right amount. As you note, applying too much will not provide good results. 

But to be clear in your response are you saying that I could 

Continue to apply caulk to the best of my ability, recognizing that sometimes the bead will be too thick, and not worry about masking tape due to next steps.
Use bare finger to smooth out. Trying not to make a mess, but also not stressing about too much (because of next step)
Use scotch brite pad to scrub away excess wet caulk that is too far outside the virtual lines.
Follow that up with a misting of water to further wash away unneeded/unsightly excess caulk. Thereby ending up with a nicer looking edge.

BTW, I am using the DAP 230. I tried researching different caulks online before starting this job (which in part led me to this site) and found many conflicting opinions. I could not determine with any confidence what was the best product to use, but did understand that 100% silicon, osi quad, etc were not right for a newbie caulker like myself. 



Nestor_Kelebay said:


> You're discovering what most of us already know, which is that the toughest part of maintaining caulk is removing the old caulk.
> 
> I would encourage you to remove all your old caulk and replace it with Kop-R-Lastic caulk, even if you have to mail order the Kop-R-Lastic. Alternatively, if you go to your local Home Depot and find Stone Mason Gutter and Siding Sealant in the aisle where they sell evestroughs, then that's the same product only in a different package. The only difference is that Kop-R-Lastic comes in 8 colours whereas Stone Mason Gutter and Siding Sealant only comes in clear and white.
> 
> ...


This sounds like a very good caulk. I totally agree with the importance of the properties you are describing. Something that is easy to use when it is time to repair has much greater value IMO. Much like I would rather have an automobile that is designed to be easily repaired, even at the expense of some longevity in any individual part. 

I quickly searched online for the Kop-R-Lastic and the HD equivalent but don't find either too accessible (I would need to order Stone Guard Gutter and Siding Sealant from Toronto), but will keep these in mind since I like the properties.

I will likely continue with the dynaflex 230 since that is what started with, but I do fear the eventual day when it will need removal. But maybe that will be for the next home owner to suffer with.



Nestor_Kelebay said:


> That looks like acrylic caulk in your pictures. I would remove what I can with a hooked blade utility knife and then see if acetone dissolves the rest. But, be warned, acetone will dissolve latex paint. I've used acetone on PVC windows without any problems with the PVC melting.


Good tip, I have some fingernail polish remover in the house and will try that for the worse spots. I do not mind repainting (and re-priming) if that makes the job easier. 

So far I have been managing by scraping off the old caulk the best I can with a 1 inch putty knife & 5-in-1 tool and light tapings from hammer as needed. This does leave a thin residue of the old caulk behind in most places, at the far outside edge where the caulk was most thin. I debated if I should purchase an oscillating tool to speed up the removal task, but then thought maybe that is a sign I was taking this removal effort too far.


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## wptski (Sep 19, 2008)

Nestor_Kelebay said:


> I would encourage you to remove all your old caulk and replace it with Kop-R-Lastic caulk, even if you have to mail order the Kop-R-Lastic. Alternatively, if you go to your local Home Depot and find Stone Mason Gutter and Siding Sealant in the aisle where they sell evestroughs, then that's the same product only in a different package. The only difference is that Kop-R-Lastic comes in 8 colours whereas Stone Mason Gutter and Siding Sealant only comes in clear and white.


It seems that the only Home Depot that stocks that product even online order only is in Canada.


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## Nestor_Kelebay (Jun 17, 2008)

wptski said:


> It seems that the only Home Depot that stocks that product even online order only is in Canada.


Open your Yellow Pages phone directory to "Caulking" and phone around to see if anyone sells Kop-R-Lastic in your area. It's an excellent caulk and I'd be surprised if none of the companies that specialize in caulking used it.


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## Nestor_Kelebay (Jun 17, 2008)

Here is a picture of me pulling Kop-R-Lastic caulk off of Suite 3's dining room window. I loaded this image onto a web site I used to answer questions on years ago, and it's still one of the first images that pop up when you use Google to search for Kop-R-Lastic.










Kop-R-Lastic takes about 3 to 5 years before it cures sufficiently to pull off "like a rubber rope". If you want to remove it prior to that, it's no more difficult than any other caulk to remove. But, better to just wait for it to cure completely, and it'll be much easier to remove.


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## Nestor_Kelebay (Jun 17, 2008)

RustNeverSleeps said:


> So far I have been managing by scraping off the old caulk the best I can with a 1 inch putty knife & 5-in-1 tool and light tapings from hammer as needed. This does leave a thin residue of the old caulk behind in most places, at the far outside edge where the caulk was most thin. I debated if I should purchase an oscillating tool to speed up the removal task, but then thought maybe that is a sign I was taking this removal effort too far.


If you find that removing ALL of the old caulk is just too big a task, then you could simply remove most of it and then caulk with WHITE Kop-R-Lastic caulk. The Kop-R-Lastic will stick to your old caulk just as well as it'll sick to your brick or your PVC windows. Then, you'll still get all the benefits of an easily removable caulk without nearly as much work.


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## Nestor_Kelebay (Jun 17, 2008)

RustNeverSleeps said:


> I debated if I should purchase an oscillating tool to speed up the removal task, but then thought maybe that is a sign I was taking this removal effort too far.


No, Google the following character string:

A. Richard lever scraper

The tool you'll see, which is made by the A. Richard company and painted red at one end, is commonly sold in hardware stores as a scraper. It's sharp enough to remove acrylic caulking effectively but not sharp enough to gouge wood or PVC.

I would use a hook blade utility knife along with that A. Richard lever scraper to remove your caulk.


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## Nestor_Kelebay (Jun 17, 2008)




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