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The application of caulk is sometimes viewed as one of surface preparation's messiest jobs. Images of caulk flowing uncontrollably from a caulk gun and the thought of caulk on hands and fingers is often enough to dampen the enthusiam of even the most ardent of do-it-yourselfers. The good news is that professional-looking caulking results can be achieved without much of the mess and bother that is often associated with this task. More good news is that skillful caulk application provides an immediate and noticeable improvement in your surface preparation and house painting results.


Eye protection, either safety glasses or safety goggles, should always be worn whenever preparing surfaces for paint. Respiratory system protection should be worn whenever you are creating dust or working in a dusty environment. Respiratory system protection should also be worn whenever you are applying solvent-based materials. Eye and respiratory system protection products can be purchased wherever workplace safety equipment is sold.

Where to caulk

Caulk is used to fill the gap between wall surfaces and wood trim. It is also used to fill the gap between joined pieces of wood trim. Caulking provides an immediate aesthetic dividend, as well-caulked surfaces have a uniform and finished appearance that is pleasing to the eye. Gaps and joints left uncaulked are easily detectable and detract from an otherwise good painting job, decorative finish, faux finish or mural.

The gaps between painted wall surfaces and painted wood trim should be filled with paintable latex caulk before the application of paint. Joints between new wood trim and wall surfaces should also be caulked. Gaps and joints should be filled with caulk so that the entire join, or joint, looks uniform. Good caulk application makes surfaces look as if they join perfectly together without any caulk.

Gaps and joints that may need caulk can often be found along baseboards, chair railing, door moldings, window moldings and mantles. Along baseboards, caulk any gap between the baseboard and wall surface. Also caulk the gap or joint between a painted quarter-round or shoe molding, and a painted baseboard. Small gaps where baseboards, quarter-rounds or shoe moldings meet in corners should also be caulked. Caulk any gap or joint between wall surfaces and the top of the chair railing. Small gaps where chair rail meets in corners should also be caulked (larger gaps should be filled with painter’s putty). The gap or joint between door and window frames and their trim molding, called a “reveal”, should also be caulked. Caulk the gap or joint where the door trim molding and baseboard meet. Caulk the gap or joint between a door frame and door stop. Caulk the gap or joint between the wall surface and a mantle. Small gaps that may need to be caulked can often be found between mitered corner pieces of painted wood trim, such as in wainscoting, door moldings window moldings, chair railing and baseboards. (Large gaps should be filled with painter’s putty)

Paintable latex adhesive caulk should be applied to fill the gap or joint between ceiling and wall surfaces and crown molding. Also use an adhesive caulk to fill small corner miter gaps in crown molding. An adhesive caulk has more bonding strength than a regular caulk, which helps to prevent crown molding from separating or gapping from ceiling and wall surfaces.
DO NOT caulk the gaps in stained, varnished or polyurethane-finished surfaces. Also refrain from caulking the gaps between ceiling or wall surfaces and stained, varnished or polyurethane-finished surfaces. Avoid caulking the gap between a painted baseboard and a stained shoe mold, or quarter-round.


Caulking overview

Begin by using a putty knife or scraper to remove any loosened caulk or other surface material where caulk will be applied. A utility knife can be used to carefully cut lengths of loosened caulk before removal. Sand the surface after caulk removal. Remove debris with a duster, and then wipe the surface with a wiping cloth or towel.

Cut the nozzle on a tube of caulk at a 45-degree angle, one-quarter inch from the tip. Install the caulk tube into the caulk gun. To begin caulking, place the tip of the caulk tube into the gap and gently squeeze the trigger on the caulk gun. To stop caulk flow after caulk is applied, turn the plunger at the end of the caulk gun until you hear a click.

To smooth caulk into place, use a three-quarter or one-inch “Fitch” or fan-shaped window sash brush moistened in water. A cup or painting pail can be used to hold water for brush moistening. Dip the brush into the water and tap off excess before brushing caulk to a smooth and uniform consitency. Wipe excess water from wood trim with a wiping cloth or towel. Allow caulk to dry overnight before painting.

More detailed coverage of the topic of caulking can be found in the book:

The Homeowner's Guide to Surface Preparation for Interior House Painting, on pages 95-98.

All content copyright Steve Broujos LLC