Caulking Wet Metal Roofs – Application Tips and Ideas

Caulking your roof when it’s raining isn’t recommended, as the water leaves the sealant joints susceptible to damage.

This means you should never apply sealants in heavy fog, snowfall, or freezing rain since they wouldn’t adhere well to wet surfaces.

If you want strong joints that will last, only apply the sealant when the substrate is dry and weather conditions are moderate.

But what if the weather isn’t cooperating, or you just don’t have time to wait for a dry day?

Is there a caulk for wet surfaces, or are there any roof sealants that can be applied in the rain? Let’s have a look…

Caulking for Wet Surfaces and Metal Roofs

Unfortunately, most of the sealants are designed to provide a watertight seal when applied on dry surfaces, and they may not adhere properly when applied to wet surfaces.

However, there are a handful of them (from specific brands) that can be applied in damp conditions.

DAP Flexible is one high-performance, clear elastomeric sealant formulated to provide a long-lasting, flexible seal even on wet surfaces.

It’s an ideal sealant for various construction and repair projects, including sealing around windows and doors, bathtubs and showers, and gutter repairs.

This sealant has excellent adhesion and will remain crystal clear and permanently flexible even on damp surfaces indoors and outdoors. The cured sealant has excellent UV resistance, is mildew resistant, and can even be painted 24 hours after application.

A few other brands of water-safe sealants are Aldoseal 399 and Lexel by Sashco. You can also look for metal roof sealants like Titebond, Nova Flex, and Butyl Tape. Although not all of them stick to wet surfaces, they can help keep water out to a certain extent.

If you’re having trouble finding any of these brands, try looking online or at your local hardware store for synthetic rubber caulking that explicitly advertises being able to withstand application in wet conditions. Maybe they can help.

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Applying Caulk Sealant to Metal Roofs and Other Wet Surfaces

Before starting with your caulking job, please read the application tips to apply them correctly. If there’s any confusion, ask the experts at your local hardware store for extra tips while purchasing the caulk.

After purchasing the caulk sealant for your metal roof to apply in the rain, do the test on a small area first to determine whether the sealant is sticking to the substrate and not washing away due to water.

Once you have tested the caulk for wet application, follow these steps…

1. Clean and prep the roofing area to make sure its free of dirt, debris, or other old caulk material
2. While applying the sealant, use a caulking gun to ensure an even and smooth application without releasing too much pressure
3. Try to go slow and apply the caulk consistently over the surface while removing excessive sealant with a damp cloth
4. If it’s still raining or you doubt it will certainly rain, use a shield or a tarp to protect the sealant from getting washed away.

How Long Does Caulking on Metal Roof Last – Tips to Make it Last Longer

Metal roof sealant can remain intact anywhere from 10-20 years, although longevity may differ based on the product and brand.

It is important to note that metal roof sealants do not last as long as metal roofs themselves and will eventually need to be replaced during their lifespan to prevent leaks.

Therefore, checking for any damage or wear of the sealant should be included in regular inspections of your metal roofing system.

Also, remember that caulk is used for filling the cracks and screw gaps on the wet roof so that dirt, germs, bugs, water, etc., cannot pass through them.

However, if after the caulking job, water doesn’t escape and remains there for long, mold or mildew can form quickly due to standing water and wet surfaces.

So, if your job requires sealing an area that gets a lot of snow or rainwater exposure, it would be best to use a temporary sealant such as sponges or rolled-up small towels that can be stuffed in cracks, joints, overlaps, seams, gutters, downspout, etc.

These sponges and towels can be later removed after the heavy rainfall, which will avoid possibly bigger problems down the line.

The bottom line

Applying caulk and sealant to dry surfaces will result in a better hold and longer-lasting product as opposed to caulking in wetter conditions.

But if the weather conditions aren’t appropriate and your caulking job can’t wait for long, follow the above steps and use the caulk designed for wet surfaces and rainy conditions I mentioned above.

With the right product, precautions, and patience, you can still get the job done quickly and efficiently.