How to Repair Gapping Baseboards

person using caulking gun on wood baseboards

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In a large majority of older homes, you find baseboards that have been caulked. Is this the right way to treat the junction between the baseboard and the wall? If not, what is the best solution?

Why People Caulk Baseboards

If caulk is applied to a baseboard, you find it in two places:

  • Top: A continuous line of caulk applied to the upper ridge of the baseboard, where the baseboard meets the wall. This caulk is usually applied because the baseboard does not hug the wall close enough. This "gappy" look only affects aesthetics, not function. Even in newer walls, you may find gentle curves which form gaps along the tops of the baseboards.
  • Bottom: A line of caulk on the floor, where the baseboard meets the floor. Over time, as joists sag, gaps develop under the baseboard. In extreme cases, these gaps are so big that they allow air infiltration and can seriously impact your energy bills. In minor cases, these gaps are simply unattractive. 

Why This Is Ineffective

Houses are continually moving, shifting, expanding, contracting. Thermal build-up and loss is one reason for this "lifelike" characteristic.

Since houses are not solid and static, they have a number of elements that adapt to movement. The best example is chimney counter flashing, which allows the roof to move next to the (unmoving) chimney, all while keeping everything nice and dry.

So when you connect the wall to the baseboard, and the baseboard to the floor, something has to give—eventually.

Caulk does have some "give," but not much. Even if the caulk is expertly applied and well-painted, cracks will form because the baseboard slightly pulls away from the wall.

By caulking baseboards, you set yourself up for continually going back and re-caulking for as long as you own the house. Re-caulking the tops of the baseboards, while annoying, will not be obvious since this area gets painted over. Caulking the lower section means applying caulk directly to your floor covering, disastrous to the looks of your house.

Here are some potential solutions:

Quarter-Round or Shoe Molding

Instead of caulking the bottoms (floor-to-baseboard junction), nail thin strips of trim called quarter round or shoe molding. This trim is flexible enough to conform to gaps, even those intermittent sags between joists. This trim comes in wood (hemlock, oak, pine, etc.) which can reasonably match a wood floor. It also comes in medium-density fiberboard (MDF) polystyrene and can be painted.

Shorter and/or Thinner Baseboards

Thin baseboards can hug the wall tighter, eliminating those gaps. Instead of 9/16" thick (just over half an inch) baseboards made of wood, look for 7/16" baseboards made of polystyrene. Shorter baseboards (2 3/4" high) are automatically thinner (3/8" thick).

Built-Up Baseboards

Another solution is to stack your baseboards the old-fashioned way, with a separate, thinner piece on top that can easily hug the wall.

Add Fasteners

Sections of baseboard pulling away from the wall can be re-nailed as long as there is a stud behind the drywall.


Even tall, thick baseboards (5 1/4" or taller) can be made to conform to the wall better when nailed down correctly. 

Ignore Them

Ignoring small gaps is another solution. Gaps that seem so patently obvious at the time of installation tend to fade from view after a while.