How to caulk corners: Tips for wall-to-wall success

This guide shows you how to caulk corners for a high-quality finish. Don’t neglect this simple step! Caulk inside corners, outside corners, and trimwork with confidence.

Caulking corners, gaps, and transitions is crucial to a quality finish. If you don’t have much experience sealing these gaps, it might seem a bit intimidating. No worries! We’re here to help.

Sealant hides the gap between trimwork and the wall, ceiling, or floor. It is also excellent for hiding cracks and imperfections. That is why it makes such a difference in your paint job and finished look.

Below you will find some tips on special situations, such as how to caulk inside corners and how to caulk outside corners. But first, here are some general directions on how to apply caulking and sealants.

1. Insert the tube into the caulking gun.
2. Cut the tip off the plastic end. Note how the tip narrows towards the end. This allows you to control the size of the bead of caulk that you will apply. For most applications, cut at a 45° angle.
3. If desired, place masking tape on either side of the joint to be sealed to create straight edges and protect surrounding materials. If both surfaces are being painted, this may not be necessary.
4. Apply an even bead of caulk following the joint or gap. Start at one trim corner if possible, and use steady motion.
5. Smooth out the caulk with a damp finger or a rubber-tipped caulking tool. Wearing nitrile gloves is always a good idea to protect your skin when using sealants.
6. Remove the masking tape before the caulking dries if you applied it.
7. Allow the caulk to dry before painting.

The corner where two pieces of trim meet is an important place to caulk. You will want to fill the gap, but don’t use too much caulk or the corner will appear rounded. Simply apply a thin bead starting at one edge and continue across the trim. Then press the caulk into the gap and smooth it out.

You may need to caulk Inside corners of walls if you see a crack. This is done the same way and is very effective at hiding cracks because of the flexibility of the caulk.

For general use, acrylic latex caulks will work very well. LePage 2 in 1 Seal & Bond Interior Caulk is an excellent general-purpose sealant for trimwork and walls. As the name suggests, it works as an adhesive and a sealant, helping to bond materials together while remaining flexible, durable, and water resistant. Seal & Bond is low odour and paintable in less than an hour.

It is a very similar process to caulk outside corners. This may be necessary when the corner transitions from one type of material to another, to hide cracks, or to caulk trim corners. Generally, outside trim corners require very small amounts of caulk. You can apply some to the area and work it into the gap with your finger. 

If you are transitioning to another material, such as paneling or wainscoting, you may want to use masking tape as described above to achieve a clean line.