When you run the ductwork for an entire shopping center or need to assemble miles of sheet metal in your shop, the last thing you need is 500 tubes of HVAC duct sealant that aren't right for the job.

We all understand how important it is for the ductwork you hang to be completely sealed and leak-free at installation. Choosing the right RTV silicone sealant will ensure the HVAC system performs its best, works well for its maximum lifespan, and doesn't become a health hazard over time.

It's also essential for you and your crew to have high-quality materials that perform great and are a pleasure to use. Quality silicone sealants save time, prevent waste, and make it easy to do your best work.

So, whether you're installing a new system, conducting maintenance on an older system, or just stocking up your supplies, consider these points when you're ready to choose your air duct sealant.

Types of Seams in Metal Ductwork

In ductwork and sheet metal fabrication, clean, smooth, fully filled seams are absolutely vital to preventing air leaks. Different types of seams have different characteristics that you'll want to account for.

Longitudinal Seams

Long, thin seams that run the length of long pipes. These long seams need a smooth, thin bead of sealant that remains flexible and strong when cured. A thinner, silky-smooth silicone is ideal for this type of seam.

Transverse Seams

These are wide, flat seams that occur where lengths of duct and other components are joined end-to-end. Thicker sealants, and fibered formulations as well, work best here. You'll often find you need up to 3-5 inches of sealant to get full coverage, and that a brush is the best application tool for these seams.

Facings, Flanges, and Couplings

These are flat surfaces or curved pieces of sheet metal that need create-in-place gaskets or a strong adhesive to join them together. A thicker bead of your choice silicone adhesive will work best here.

Remember, even small air leaks can cause the system to lose power, efficiency, and the ability to filter the air. Sealing all gaps is a step that must be done right from the very beginning.

Environment

Every HVAC installation is different and will come with tough conditions that will create wear and tear on the sealant for years to come.

Extreme Temperatures and Fluctuations

HVAC ductwork frequently runs through uninsulated attics, crawl spaces, and commercial or industrial spaces. You'll want to choose one of the several top-quality RTV silicone sealants we offer to hold up from the bone-deep cold of winter to the molten swelter of high summer.

Our Pro Grade RTV Silicone Sealant or Premium 100%RTV Silicone Sealant are both excellent choices for long-term flexibility, rugged durability, and superior adhesion in harsh conditions.

Speaking of high heat, some areas of an HVAC system can get very, very hot. A good example is a rooftop unit on a concrete building that receives direct sunlight. You could boil water up there! Be sure to keep high-temp silicone sealant on hand for sealing the ducts operating in these types of environments.

Wet Environments

Frequently, HVAC ductwork is exposed to damp or wet conditions. This water can cause all sorts of damage to poorly-sealed metal. It can also foster aggressive growth of mildew and mold – which is a worst-case scenario for long term climate control systems.

Our Kitchen and Bath Mildew Resistant RTV Silicone Sealant is a fantastic choice for sealing ventilation systems in kitchens, bathrooms, and anywhere that excessive moisture could wreak havoc on unprepared sealants.

Various Building Materials

The materials you're sealing up or sticking together is one of the most important considerations in choosing the best sealant for a job. As you seal cracks and crevices between HVAC ductwork and the buildings they serve, you're likely to encounter metal, brick, stone, vinyl, concrete, wood, and other surfaces that you need the sealant to adhere to.

In particular, vinyl requires a slightly stronger formula. For jobs involving vinyl, make sure you purchase Select Neutral Cure 100% RTV Silicone Sealant.

Location and Appearance

Other factors to consider are cosmetic.

For instance, some silicone sealants come in a variety of colors. Look for choices such as clear, white, black, red, and aluminum when you want seals that match their surroundings.

Odor is another big factor to remember. If you're installing ductwork in an enclosed area, choose a low-odor sealant.

Finally, think about drying time. While quick-drying silicone will usually be the ideal choice, there may be times a slower cure is what you want.

Take the Time to Shop for Good Sealant

When it comes to air duct sealant, buying the best quality is absolutely vital. Good sealant will prevent mold, dust and pathogens from building up inside HVAC systems. It will last in the harshest conditions without deteriorating, cracking, or leaking.

You can have sealant that does the job without sacrificing extra time or money. The right sealant also won't drive you nuts by making a tedious job unbearable. In fact, as you reach for the Silicone Depot box, pat yourself on the back for buying the perfect sealant for your next job!

Need help figuring out the perfect sealant for your next project? Give us a call at 812-824-8000 for expert advice on which sealant to choose.