A number of aftermarket roof sealants are available, including urethanes, acrylics and liquid rubber. Liquid EPDM rubber is by far the most durable of the sealants available and has the widest range of applications.
It is more water resistant than other rubbers, including neoprene. It is more resistant to swelling and has a wider range of acceptable temperatures. It can be applied directly to practically any roofing material other than asphalt and can even be used on wood that has been primed.
Liquids have an obvious advantage over sheets. Sheets have seams. Seam sealers eventually deteriorate and water gets through the seams and under the sheeting.
Liquid EPDM can be used on top of neoprene, although some pre-treatment of the surface is required. Just knowing that the liquid rubber is recommended for use on top of the other type of rubber should be an indication that the material is more durable.
Liquid EPDM can also be used on top of polyurethane after a light sanding. It is somewhat surprising that urethanes are still used as aftermarket roof sealants. It is known that the structure is damaged by UV light and that discoloration occurs relatively quickly. Anyone who has made the mistake of using urethane as a roof sealant should consider applying liquid EPDM to truly protect the roof.
The liquids can also be used to seal existing leaks. They are self-adhering and fill up tiny fractures that let water through. It is a good idea to use a thick coat and cover the entire surface instead of attempting to only cover the leaky area.
When covering the entire roof, the liquid rubber reduces heat buildup. Not only does the roof stay cooler, but the interior of the building or the vehicle will also stay cooler. This benefit may reduce heating costs and keep the occupants more comfortable.
Liquid EPDM has become the most popular choice for RV roofs, because of all the above-mentioned advantages. It extends the lifespan of the roof and requires less maintenance. It lasts up to three times longer than any other aftermarket RV roof sealant and also reduces noise from rain.
As far as price goes, most sealants are similar in price. Depending on where you buy, EPDM may be a little more expensive, but because primers and additional coats are not usually necessary, and because it lasts so much longer, owners who choose this aftermarket roof sealant save money in the long run.