When it comes to sealants–product used seal gaps and holes to make something air and water-tight–there are only really two options: polyurethane and silicone-based caulks. On the surface, the difference between the two happen to be their chemical compositions (silicone is an inorganic substance, while polyurethane is organic). But there’s more to it than that, because their composition affects how the break down which affects how long they last. This article will focus on the difference between polyurethane caulk and silicone caulk.
As you’ll soon see, polyurethane, while being a heavy-duty adhesive, is also an organic substance that breaks down with constant UV exposure. Silicone, however, doesn’t, making generally a better option. In the post, read up on the details of these two types of adhesives and find out which one is best for your caulking project.
Polyurethane is an organic compound produced by the reaction of glycol and an isocyanate. It is moisture- and corrosion-resistant. Consequently, polyurethane is useful as a heavy-duty adhesive, sealant, and caulk. Polyurethane caulk can be applied with a caulk gun. It is available in tubes that will fit the common caulking gun.
Not only is polyurethane caulk noted for its resistance to moisture, chemicals, and corrosion, it provides excellent flexibility. When joints expand and contract, polyurethane caulk is flexible enough to resist cracking and loosening. Polyurethane caulk is available in industrial strength which requires careful mixing of ingredients before it can be used. It is also available in a consumer-friendly ready-to-use form that requires mixing before it can be used.
Silicone caulk is another kind of caulk, but it is different from polyurethane caulk. Unlike organic polyurethane caulk, silicone is inorganic. Being inorganic, it will not break down under prolonged exposure to the UV rays in sunlight and extremes in temperature. The lifespan of a joint sealed with silicone caulk is over twenty years, but a polyurethane-sealed joint will only last about five to ten years.
Silicone caulk is prized for its elasticity and it adheres well to any smooth surface except wood. It is ideal in bathrooms, kitchens, laundry rooms and any room with high moisture levels because silicone caulk is water resistant. You can also get a silicone caulk that contains a fungicide (for use in bathrooms and other areas not used in food preparation).
Which Caulk Is Best For Your Project?
Silicone caulk is generally far superior to polyurethane caulk; however, it has some limitations. The biggest issue with silicone caulk is it cannot be painted. You must use polyurethane caulk or another kind of sealant for areas that will be painted, such as drywall and wood.
Here is a general guide to help you decide which type of caulk is best suited for your project.
When To Use Polyurethane Caulk
Use polyurethane caulk when you are caulking to wood or other surface that must be painted. Be aware of the fact that is will adhere very well to most surfaces but it will not hold up as well as silicone caulk in high sunlight exposure. Most manufacturer warranties last for five years but you can expect up to ten years if sunlight exposure and joint movement is minimal. It is easier to clean up than silicone caulk and takes about 24 hours to dry completely. Once dry, it dries hard and can be difficult to remove.
When To Use Silicone Caulk
Silicone caulk is far superior to polyurethane for certain applications. It adheres very well to almost any material but it does not adhere well to wood surfaces. Also, silicone caulk is not paintable, so be careful about where you use it. The silicone in the caulk prevents the paint from bonding with the caulk. On the other hand, it is ideal for wet or exterior surfaces because it holds up well in sunlight and extreme temperatures. Most manufacturer warranties are twenty years. It costs about twice as much as polyurethane caulk but it will last twice as long.
Sealing Around Plumbing Fixtures
One of the best uses of silicone caulk is for sealing around plumbing fixtures such as bathtubs, showers, toilets, and sinks. It is also excellent for weatherproofing your house. Use it to seal around doors, windows, and utility cables coming in from outside, and you will be going a long way to minimizing drafts. Sealing those openings can also help keep out rodents and vermin.
In Colder Temperatures
Silicone is the best sealant to use in colder temperatures. Unlike polyurethane caulk, the cold temperature does not affect application. In cold weather, polyurethane caulk becomes harder to apply. Also, it will not make a permanent bond when the temperatures are too low. On the other hand, silicone caulk remains flexible.
When it’s time to replace the polyurethane caulk, you can replace it with silicone caulk, provided that you take the time to remove all of the polyurethane material first. Depending on your project, it may well be worth the effort.
Once applied, silicone caulk has a fairly long drying time, and it produces unpleasant or potentially harmful fumes during its installation. Accordingly, you need to ensure the room is well-ventilated during use. It also needs to be protected from moisture for several days after application so that it can dry well. For those reasons, you may want to consider using a professional service for larger caulking jobs.
Contact Waterproof Caulking & Restoration For More Information On Polyurethane vs. Silicone Caulk
If you need help with a waterproofing project, call the experts at Waterproof Caulking and Restoration for information about the best waterproofing and caulking products for your needs. Contact them today to learn more about the professional commercial caulking services or to inquire about the best types of caulk for your project.