How-To Caulk Tips for First Timers

Caulking 101

Yeah, we get it: caulking isn’t on your bucket list. That’s why you need this info. You want to know how to caulk and how do it right the first time, so you don’t have to do it again. Consider this a necessary crash course that will help you get things done right so you can focus on your actual bucket list, not on your caulking to-do list.

But first, you should probably know: why bother to caulk in the first place?

It’s simple: to keep the outdoors outside and the indoors inside. The average home has air leaks equivalent to leaving open a three square foot window all the time. That’s money just going out the window, not to mention comfort. So, seal ‘er up. You’ll save money. And when you follow the guidelines below and use a Sashco product, you’ll save money and time, avoid headaches, and look darn good doing it. Watch the video below to get started, then finish reading and you’ll be on your way.

1. Watch the Weather

Weather affects:

  • The size of the joint at the time of caulking – like your knee joints and tennis elbow, joints will swell in extreme temps
  • The contaminants on the surfaces of the joint, like dust, pollen, dew, etc.
  • The ability of the caulk to properly adhere to the surfaces
  • The ability of the caulk to properly cure and develop its ideal physical properties – caulk can’t cure properly in freezing temps, nor in extremely hot temps.

Caulk in ideal weather conditions whenever possible. What is ideal? 40°F and rising and 90°F and falling. This also applies to the surface temp. It should be in that range, too. (Of course, Sashco has products that can work outside of that. But still – this is best.)

But what about wet or snowy conditions? If it has just rained or snowed and you’re using a water-based product, allow the surfaces to completely dry before caulking. Wet surfaces will make proper adhesion difficult and will prevent the caulk from curing correctly. (Yep, you could get a bunch of caulk dripping down the side. Yuck.)  Also avoid applying caulk if rain or snow is expected within 24 hours. If you absolutely have to caulk, cover it with a tarp to prevent moisture from getting onto the caulk and causing it to wash out.

Sticks to Wet Logo(What you REALLY wanted to know: You can ignore these conditions and caulk to your heart’s content if using Lexel® or Through the ROOF!®, both of which can be applied in temps down to 0° and to wet surfaces.)

2. Surface Prep, Surface Prep, Surface Prep (Preach It!)

Good surface and joint preparation is the most important pre-requisite for a professional and long-lasting caulking job. It’s what will show others you really know how to caulk.

Remove old caulk.


Use a putty knife, painter’s 5-in-1 tool or other similar tool to remove all of the old caulk in the joint. A heat gun can be used to soften old caulk and loosen paint to make removal easier.  Caulk remover can also help remove all types of old caulk.

Clean the surface. (Like, real clean, not a quick wipe down with a dirty rag.) Make sure the surface is completely free from old caulk, peeling paint, weathered/gray wood fibers, grease, oil, wax, pollen, dirt, rust, mold, mildew, soap scum, etc. A wire brush works well to remove contaminants, and a drill-mounted wire wheel is often the best answer for cleaning dirty, unsound concrete. To clean off oil or grease, use a grease-cutting cleaner. After it all, thoroughly rinse and vacuum everything out. Remember, the best caulk in the world won’t work when it’s sticking to stuff that will fall off anyhow.

Chemicals clean, but they also prevent proper adhesion. So, thoroughly rinse off any chemical cleaners.

Use Filler RopeTM or another backer rod in all joints that are ¼” wide and ½” deep or more. Why?

  • It creates the ideal joint design (two points of adhesion with the product free to move in the center), which aids in both performance and easy fixes when there is extreme movement and the caulk tears.
  • It saves money. Filler Rope is cheaper than caulk.
  • Tooling (smoothing) is easier. More pressure can be applied to the caulk when Filler Rope is behind it. This added pressure forces the caulk into intimate contact with the sides of the joint for better adhesion. (Yes, intimacy in caulking is a good thing.)

To install Filler Rope, simply press the material into the joint using your hands or an appropriately sized tool. Recess it enough to allow for 1/4″ – 1/2″ depth on top for the caulk. And stay away from sharp tools when doing this. Any holes or nicks in it can allow moisture to get into the backer rod, as well as “out-gassing” that can cause blisters in the caulk.

home repair projects

Primers are a good idea. They aren’t required, but they’ll definitely help, especially in joints that are subject to regular difficult stress, like log homes or a home in extreme wind. Primers promote even better adhesion for a longer lasting seal. Any normal paint primer will do the trick.

3. Use the Best Sealant for the Job

Good news: Sashco makes only the best. Cheaper products will need to be replaced after a few years. Not sure which product is best? Find your project on the list and get the product advice you need.

4. Apply the Caulk Properly

Big Stretch Trim Caulking







A quick run down the joint with the caulking gun won’t do the trick. Here’s how to properly apply caulk.

Cut the nozzle to the right bead size.  Markings are included on each cartridge nozzle and correspond to different bead sizes. Cut the nozzle at a 45° angle at the mark for the bead size you’ll need. Puncture the inner seal (if there is one), place it in a caulking gun, and you’re ready to begin. (Obviously, no caulking gun is required with a squeeze tube.)

Practice makes perfect, so do some practice caulking on a scrap piece of cardboard or newspaper to get a better idea for how the product feels and to avoid those weird bumps from pulling the trigger over and over.

Now you’re ready to apply the caulk. For good measure, start your first caulk line in an inconspicuous area (in case your practice wasn’t enough). Hold the nozzle opening parallel to the joint and apply a 2-3 foot bead. Don’t do more than this because you’ll need time to smooth it before it starts to dry and skin over. By the time you get to those areas that are more noticeable, your new-found skill will shine through with beautiful results. If you do mess up, simply scrape out the bead right away, wipe down the surface and start over.

“Tool” (smooth) the bead. “Tooling” is the process of gliding over the bead of caulk in order to smooth it, making it neater and further establishing good adhesion. Is tooling necessary? Yes, but only if you want your job to last a long time so you won’t have to redo it. Tooling can be done with a finger or with various tools, like the back of a spoon, a trowel, a beading tool, or Sashco’s favorite: foam paint brushes. Avoid scraping off too much of the caulk during tooling. It wastes a lot and can “starve” the joint of enough caulk to stretch and seal properly. Use plain water to aid tooling water-based caulks. Use either soapy water or mineral spirits for solvent-based caulks.

Tooling (smoothing) Log Jam

Clean up messes right away. Dried caulk is hard to remove, so keep rags handy for clean up. If masking or blue painters tape is used along the sides of the joint, make sure the tape is removed immediately after tooling is complete (before the caulk skins over) so that it will pull away cleanly and leave a smooth, even line.

So now you know how to caulk. As we like to say around here, “Nice caulk.” Send us some pictures, then get on with that bucket list.