Caulking in the rain isn't ideal. Wet caulk can lead to a host of problems, including improper adhesion and future mold growth. But caulk manufacturers also know that sometimes you don't have any other options. Perhaps you're trying to seal a space quickly to prevent water damage or have a rainy or snowy forecast for a few weeks. Whatever the reason, caulking in wet conditions is possible with the right product and precautions.
Assess the Situation
Start by making sure this is a caulking job that can't wait. While caulking in the rain is possible, caulk and sealant applied to dry surfaces will likely adhere better and last longer.
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The biggest concern with wet surfaces and caulk is mildew and mold. The goal of caulk is to seal off an area, making it impossible for dirt, germs, bugs and debris to make their way through cracks in your home. But if water also can't make its way out of those cracks on either side, it will quickly turn into mildew or mold. If your caulking job involves sealing in snow or rainwater, it's best to find a temporary method of sealant, such as rolled-up towels or sponges stuffed in cracks, to avoid creating a much larger problem.
Get the Right Caulk
If your job can't wait, start by buying the proper caulk. There are only a few on the market designed to be applied in wet conditions, so make sure you're selecting the correct kind. A few of the brand names on the market are Aldoseal 399, Lexel by Sashco and DAP Flexible. You can also look for a synthetic rubber caulk, as many types of this caulk are safe when applied to wet surfaces.
If you can't find any of these brands or a general synthetic rubber caulk, look online or at your local hardware store for caulks that advertise as being safe for application in wet conditions.
Do the Job Right
Even when caulk is approved for wet conditions, take extra care to perform the job correctly. First, since each sealant is a little different, make sure you read the application tips that should appear on the tube for specific instructions. In addition, ask the experts at your local hardware store for extra tips when you buy it.
No matter the caulk, it's always important to do a test strip on strong paper before you get started. That will give you a feel for the caulk gun so you don't accidentally release too much or too little product in the area you're sealing.
Additionally, make sure the area is prepped before you start caulking. Getting rid of old caulk, dirt and materials will go a long way in helping the new sealant stick. Break up the debris with a putty knife and then thoroughly dry the area as much as possible under the conditions.
Finally, go slow and steady as you try to apply the caulk as consistently as possible.
Rainy conditions aren't great for caulk application, but if you follow these instructions with the right product, you can produce a long-lasting seal that does its job.