Evaluating Caulking 101

Rot, Mold, Mildew and water staining can all result from deteriorated caulking. There are no two ways about it; your homes last line of defense against these defects is caulking. In this post we will share information about common caulking defects and which ones may require immediate attention. Before we begin, lets answer a few questions

What is Caulking? Is it like silicone? What about latex caulking? Are they the same thing?

First order of business; caulking is a medium utilized to fill or seal gaps or seams. If you were to use cotton candy to seal the gaps in your boat, then to you, cotton candy is caulking. DISCLAMER: please do not use cotton candy to seal your boat, or anything, ever. All joking aside; typically, when we are talking about caulking, we are referring to one of two products: silicone and latex. There is a myriad of subsets for these two products but this isn’t a building science class so we will just go with the two for now.

How to Identify Deteriorated Caulking:

Identifying deteriorated caulking is not difficult at all. The tricky part is knowing where to look and making certain to inspect all of the structures caulking. In general, anything that was installed after the rough framing may require caulking. Examples of these areas are roof flashings, exterior doors windows, backsplashes, sinks, bathtubs and shower enclosures. Now I will outline the inspection process for you. Ok here  it is! Go to these places and look at the caulking, does it look good?

Caulking done right

Or does it look bad?

inspection defect caulking

That’s it! Caulking is a pass-fail inspection. It is either doing its job or it is not. You can also gently pick at the leading edge of the caulking with your fingernail. If there is any separation from the material that it is supposed to be sealing, then it is no longer doing the intended job and should be replaced.

Failed caulking can be lightly cracked on the edges.

inspection defect caulking

Left uncorrected these minor imperfections can cause some serious damage. The effects of failed caulking are often compounded by the moisture sensitivity of modern building products. Many trim and siding products in use today are little more than a mixture of sawdust and glue masquerading as wood.

Have a look at this window trim, it is completely deteriorated. This damage is the direct result of deteriorated caulking.

inspection defect caulking

If this caulking had been evaluated and repaired this trim would not need to be replaced.

inspection defect caulking

Here is an example of how neglected caulking can get real expensive real fast.

inspection defect caulking

Approximately 30% of the siding on this structure had to be replaced because of……. you guessed it, failed caulking. The seams of engineered siding require a rigorous maintenance routine. If moisture contacts the unsealed edges of this (and many other) products they will eventually fail.

Analyzing Caulking Deficiencies

Now that we have familiarized ourselves with some common deficiencies let’s investigate them a little deeper. Recall the hairline crack, these images are from the upper portion of an interior window. This area will likely never see any significant moisture. While still technically a defect, this condition provides very little potential for further damage. Now, if we observed this exact same defect at the sill of this window, it would be another story. The difference is that at the windowsill there is a higher potential for water damage due to condensation running off of the window.

The two examples used for the exterior defects were admittedly near worse case scenarios. Understand that inspectors see these scenarios EVERY DAY. Imagine this, the rotted trim started out as just a tiny hairline crack. Once moisture was allowed to get past the caulking the problem compounded, without maintenance this failure was eminent. To boot, now we are looking at a couple hundred-dollar repair bill from the same contractor that could have re-caulked the entire window for $20! These defects are why your report may contain a laundry list of seemingly inconsequential weatherproofing defects that your inspector recommends be corrected.


What we can take away from this is that all of you can identify caulking defects. However, to be effective evaluators we need to educate ourselves on two things. The first is where to look and the second is understanding the future impact of what you are looking at today. While a bit of missing silicone on a kitchen backsplash may not be cause for major concern; missing exterior silicone on a north facing window in Colorado Springs is a different story altogether.


Wait don’t leave just yet. We would love to hear from you! Did you love this content, or perhaps you find it a bit elementary? Either way we would be extremely grateful if you have the time express how you felt about the value of this article. As always, we would be delighted to sit down and discuss the home inspection process with you. Feel free use our online tool to set up a consultation that works with your schedule.