Caulk Question

[Mike Goetzke]

Installing thee 6' x 3' upstairs windows. One is 99% done thanks to some help here with my other questions.

I used OSI Quad to seal up the window flange to house. Then I applied the brick mold per Andersen's instructions leaving a 1/4" to 1/2" gap between the window and trim. I'm close to 1/4" but applied the OSI Quad to the gap and it's making my great looking window and trim look terrible. It's clear (which magnifies the problem) but can be painted later. This caulk will not let you smooth it with a finger or tool. It is too sticky.

Do I need to look for another type of caulk for this part of the job? Suggestions appreciated.

 

[Cheese]

I’ve used a lot of different caulks but my hands-down favorite is Vulkem by Tremco. It doesn’t shrink and maintains its elasticity forever. I’ve removed the stuff after 8 years of outdoor service and it’s still as elastic as a rubber band.

It’s also tenacious and sticks to everything. Messy to apply but worth the effort.

 

[Bob D.]

Is this the method you are using?


OSI says don't tool.

 

[Mike Goetzke]

Maybe use a foam rope filler and caulk that can be smoothed?

 

[Lincoln]

Try spraying water/detergent on your finger, will stop it sticking.

 

[usernumber1]

I think there's tooling and then there's actual tooling by a 'mastic person'.


I can see OSI saying don't tool because people use a finger and make the joint too thin.

The video shows how to shape it / I would use this method with no hesitation however it's greatly skill dependent.

 

[Mike Goetzke]

Think I know my issue. Andersen specifies the 1/4" minimum gap around their window but I've seen like 3/4" board used as trim. In my case using decorative brick mold creates a deep cavity because it like 1-1/4" deep. So that's why I'm thinking I need a foam backer to fill most of the cavity.

 

[Mike Goetzke]

OK - I run out of OSI Quad clear for sealing around the windows so go to get another tube and all they had was Quad Bronze. This Bronze was way less viscous than the clear. Wonder why?

 

[Bob D.]

Check the dates on the tubes, and maybe also some differences in the composition.

I just tossed 6 tubes of sealant that were outdated and when I checked were not running as smooth as they did when I bought it 2 years ago. I bought a case of 12 but only used half.

 

[Cheese]

Check the dates on the tubes, and maybe also some differences in the composition.

I just tossed 6 tubes of sealant that were outdated and when I checked were not running as smooth as they did when I bought it 2 years ago. I bought a case of 12 but only used half.

Amen...I also learned the hard way. If I need 4 tubes for a project I'll purchase 4 tubes but the days of keeping "a few extra tubes of caulk around" are long gone. That way the most that get tossed is only 1 of each type.

 

[Tom the Remodeler]

Hi Mike!

A few thoughts/observations:

- I noticed that you didn’t mention flashing tape. I assume this was an omission in your description, but it’s important that you’re relying on the flashing tape to keep water out and not your caulk.

- It is absolutely advisable to use “backer rod” to achieve a hourglass shaped caulk bead, since the ASTM standard assumes this shape

- I only use Quad when caulking vinyl or aluminum where an exact color match is important. No amount of “wetting” your finger or otherwise will allow you to tool it, it skins over almost immediately and needs to be essentially perfect right out of the tube

- Vulkem is my “go-to!” exterior caulk. As mentioned by Cheese, it seems to remain flexible even after decades of service

- Most caulks will eventually fail, so it’s important that you’re not relying on caulk as your WRB

 

[rst]

As a commercial glazer for 40 years my go to is Sikaflex or Tremco.  Checking expectation dates is critical as most quality caulks are moisture set.  We commonly have one inch gaps to fill... definitely a learning curve.

 

[peter halle]

And for those who wonder why there are instructions or don'ts about caulking...

Caulking has a coefficient of stretch.  So a thinner bead can stretch less than a larger bead before it fails.  Good for keeping water out but might not be as pretty to us carpenters who desire tight joints.

Second point is that caulk likes to stretch like a marriage - between two surfaces (the married couple) but when you work it with your finger your are introducing the bottom of the joint (the in-laws) and that typically causes issues because the lack of stretch.

So, a perfect caulk joint is a union of space, product, and only two surfaces.  Of course a backer rod could possibly be used to run interference against the in-laws.

Peter

 

[Cheese]

Second point is that caulk likes to stretch like a marriage - between two surfaces (the married couple) but when you work it with your finger your are introducing the bottom of the joint (the in-laws) and that typically causes issues because the lack of stretch.

So, a perfect caulk joint is a union of space, product, and only two surfaces.  Of course a backer rod could possibly be used to run interference against the in-laws.

That’s cute Peter…it should be turned into a sticky on the FOG.  [smile]

 

[Mike Goetzke]

Hi Mike!

A few thoughts/observations:

- I noticed that you didn’t mention flashing tape. I assume this was an omission in your description, but it’s important that you’re relying on the flashing tape to keep water out and not your caulk.

- It is absolutely advisable to use “backer rod” to achieve a hourglass shaped caulk bead, since the ASTM standard assumes this shape

- I only use Quad when caulking vinyl or aluminum where an exact color match is important. No amount of “wetting” your finger or otherwise will allow you to tool it, it skins over almost immediately and needs to be essentially perfect right out of the tube

- Vulkem is my “go-to!” exterior caulk. As mentioned by Cheese, it seems to remain flexible even after decades of service

- Most caulks will eventually fail, so it’s important that you’re not relying on caulk as your WRB

Ha - even caulk isn’t simple! Yes, I made sill caps and used flashing around the window flange sides and top. Now this is another learning curve I had issues with. I installed a couple of windows on the first floor a few years ago. I made sill caps with the three piece method. For this project I liked this flex-tape I saw on the internet that allows the cap to be made with a single piece. It’s hard to explain but stretching is good for the corners but not desired everywhere else. Problem is the tape wants to stretch where you don’t want it too and is very sticky. Good thing my granddaughter wasn’t around when I was discussing my dislikes of this with the flex-tape.

So far the windows look great! Good thing I removed the clear from the brick mold to window because I found Quad has many custom colors available including one that matches my Andersen window frame color.