Splits & Tears in Your Caulk? Oh My! Substrate Failure

Those splits and tears in your caulking look ugly, and it's time to fix them. Below are some examples of Substrate Caulking Failure

Substrate Caulking Failure An example of substrate caulking failure on a wall and trim. - See more at: http://www.scottpaint.com/technicaladvice.asp (This site also lists lots of other failures if you're having other issues.)

As review, there are three types of caulking failures:

  1. Cohesive failure - when the caulk bead splits down the center. Read about causes and fixes here.
  2. Adhesive failure - when the caulk bead doesn't stick to the surface anymore. Read about causes and fixes here.
  3. Substrate failure - when the caulk bead tears off part of the surface. This is today's subject.

Let's talk substrate failure.

If you've ever seen flakes of wood stuck to a bead or caulk, or bits of concrete patch stuck to crumbling asphalt, you've seen substrate failure. When the caulk has stuck so well that what it's sticking to decides to just give up, you have substrate failure.

Possible causes are:

1. Weak substrates

Wood fibers are sun damaged prior to caulking, or asphalt is...well, asphalt. (Asphalt is inherently weak.) The surface is old and in need of replacement or some major TLC. Either way, when you put caulk on it, the caulk will adhere really well while the surface won't and you're left with damage.

2. Really strong (too strong!) adhesive properties in the caulk

You want your caulk to adhere to the substrates, but you don't want it to have so much internal strength that it won't stretch and will instead pull at that surface and damage it. How to avoid this: choose the best product for the job. That industrial-strength subfloor adhesive is not usually the best choice for sealing around your window that will undergo movement with normal changes in humidity and temperature. 

Solutions: In both cases, it's going to mean fixing the substrate. These fixes can vary, depending on the substrate. It may mean just sanding down the wood trim to blend in with the rest. It may mean some patching of the crumbling asphalt. In extreme cases, it will mean completely replacing the substrate. Circumstances will vary, so contact us for help sorting out the particulars of your situation, and for information on Sashco's premium products that can help you avoid this in the future.