I get a lot of comments from people wondering why I don’t use silicone caulk on things like leaky wood windows or doors. Silicone seems to be the savior of the caulk aficionado. The creme de la creme of the caulk kingdom with nary a competitor to be found who can challenge its amazing performance. Don’t get me wrong I like silicone, but like everything it has its time and place and used outside of that it creates more problems than it solves.
In this post I’ll lay out my case and all you silicone advocates can argue with me in the comments below. I doubt you’ll change my mind because my opinion is based on years of experience trying to dig the stuff out of old houses in places it never should have been, but you’re welcome to try.
Silicone + Wood = Bad News
When used on bare wood silicone can be deadly and destructive. It grabs on tenaciously, which you might think is a good thing, right? After all the you want your caulk to have great adhesion and flexibility so it will seal things up for a long time. Well, just like everything silicone caulk has a lifespan. According to United Silicones, silicone has a minimum life expectancy of about 20 years which is a good long time.
So what happens at the end of that 20 years? Well, you have to dig out the silicone and replace it with either more silicone or some other sealant. If you have ever tried to dig out silicone from wood you’ll quickly discover that even on old silicone this is a monumental task that yields terrible results. Removing all the silicone is difficult to accomplish as there is almost always some residue and when you remove it from wood it inevitably grips onto the wood fibers and pulls them with it resulting in a mutilated work piece that requires lots of repair.
When it comes to things like old windows traditional glazing putty is a much better choice. It has a similar lifespan of 20-30 years and at the end of that time it can be removed without damaging the wood. It responds to steam (see the video below) or heat to facilitate removal unlike silicone, and even if some of it remains it is compatible with the new putty or paint during reinstallation. That brings up another point about silicone.
Silicone is Not Paintable
I think most of you probably already know this about silicone that it is not paintable. No how, no way. Paint simply beads up and falls off pure silicone caulk. Since the typical house is painted every 10 years that means you’re gonna have to figure out something to do with the areas that have silicone. Color change? Not for you if you’ve got silicone caulk on your house.
That little point I mentioned earlier about there always being some residue after removal of silicone once again wreaks havoc here. You will have sloppy paint lines wherever the silicone was unless you remove every trace of it which is near impossible without replacing the wood member.
Where Does Silicone Belong?
It may be easier to say where silicone DOESN’T belong than where it does so let’s go that route. Silicone caulk is excellent at water sealing and flexibility so it has its place in construction. There are two main places it never should be installed, wood or any painted surface. If paint will ever be applied to an area, then silicone does not belong there, ever, in any way. If you have a wood element (painted or not) in your house silicone should never be applied there either.
Most any other application is usually fine for silicone caulk though I use it sparingly. I’m a fan of siliconized acrylic caulks, or their more serious cousin, urethane caulks, because they are more easily reversible and they are almost always paintable.
Please do the next guy or girl a favor and don’t use silicone caulk as a cure all for leaks. It was never designed for that and it usually causes more trouble long term than the short term benefits. Think first and caulk second. Please silicone safely! 😉
Founder & Senior Editor
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.