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8 Common Causes of Gaps in Baseboards

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Under normal circumstances, there should be no gaps between baseboards and the wall or baseboards and flooring. However, for various reasons, sometimes people find gaps in their baseboards.

If you recently noticed gaps in your baseboards, you may be staring at what may or may not be severe structural damage. You’ll be able to tell how bad things are once you figure out the cause of the gap.

In this article, we talk about eight common causes of gaps in baseboards. After talking about the causes, we describe fixes. Read on for the details.

Close up of white plastic plinths on dark wooden oak floor parquet

8 Common Causes of Gaps in Baseboards

As we said already, the gaps in your baseboards may or may not be an issue. Once you identify the cause, you’ll be able to tell.

The following are some of the causes of gaps in baseboards.

The Gap May Be Normal

In some cases, the gaps in your baseboards are normal.

Although there’s no use for them, they are sometimes there because the structure is not perfect. In some cases, the gaps manifest as the baseboards settle or move with time.

If the gap in your baseboards is there because of the structure or because they settled, that is normal. You do not have to bother about such gaps.

Uneven Floor

Sometimes the gaps in your baseboards are there because your floor is uneven.

It is not uncommon to have an uneven floor in a home. In fact, if your building is old, you are highly likely to find some uneven floors in it.

While an uneven floor may be a consequence of structural damage, sometimes the cause is minor.

In other words, your floor may be uneven for other reasons, including the subflooring type, building age, structural layout, and flooring material.

Building age affects the flatness of your floor because soil conditions around the foundation may change with time.

In other words, as the soil beneath your foundation changes, the foundation may move. When the foundation moves, it may sink, causing the floor to become uneven.

If the movement is minor, there may be no gap. But if it is significant, there will be gaps in your baseboards.  

preparation for the installation of tiles

Foundation Settlement

Whether uniform or differential, if your foundation settles, it may create gaps in your baseboards.

Uniform foundation settlement is typically not very harmful to structural integrity. It usually leaves no cracks in the building. So, on assessment, the building should be OK.

Conversely, differential foundation settlement is typically dangerous. It leaves cracks in various parts of the building and is a sign of serious structural damage.

Various things may cause foundation settlement. This could be poor foundation construction, water damage, changes in soil structure, or vegetation.

Whether it’s uniform or differential, if you believe your foundation has settled, get a foundation repair professional to assess the situation. After assessing it, they will tell you how bad it is.

Inexperienced Contractor

An inexperienced or poorly skilled contractor can cause gaps in baseboards through various errors. One such way is to cut the baseboard unevenly.

A poorly skilled contractor may also leave gaps in your baseboards if they do not use the best material for your flooring.

Low-quality flooring material will succumb to wear and tear faster than high-quality material. When this happens, the flooring may shrink, creating gaps between the flooring and the baseboards.

Shrinking is particularly common with floorings like vinyl tiles and laminate floorboards.

If the contractor that did the floor of your building is not well skilled or is inexperienced, they may not install the material properly.

Unfortunately, this may lead to unwanted changes to the floor as time passes. Of course, when the floor loses form, gaps may form between the floor and the baseboard.

Your Floor Joists Are Rotting

Floor joists are the floor framing that supports the weight of every item in a room. They span horizontally across the foundation, support beams, and walls.

The gaps in your baseboards may be because your floor joists are rotting. Floor joists are wooden, and of course, when they start rotting, they will grow weaker.

As your floor joists grow weaker through rot, their ability to support the weight of items in your room drops.

In other words, rotting floor joists cannot hold baseboards and your flooring up effectively. As a result, the baseboard and flooring drop from their usual positions, creating gaps in your baseboards.

The primary reason for rot in floor joists is moisture. Without moisture, the chances of rotting are pretty low.

So, how do floor joists get moist and then rot?

How Floor Joists Rot

Your floor joists may be absorbing moisture from the soil outside if the soil outside is higher than the floor joist. Apart from that, if your building is not damp-proof, rising damp will ultimately get to the floor joists in its path.

If there’s a leak around your floor joists, they may become wet and eventually rot. Such leaks may come from cracks, leaky pipes, or other sources.

If the crawl space beneath your floor joists is not well-ventilated, condensation may occur. When this happens, moisture will accumulate in the space, enter the floor joists, and cause rot.

Spacious hallway with carpeted floor

There Used to Be a Carpet on the Floor

If you see gaps in the baseboards of your new apartment, the gaps may be a sign that there used to be a carpet on the floor. Such gaps typically have the same measurement throughout.

The consistent gap size is how you know there may have been a carpet on that floor in the past.

People typically slip carpets beneath baseboards to make the space look prim after installation. This is why there may be gaps in the baseboards of an apartment that had carpets on the floor.

In the cases where the baseboard installation comes before the carpet, some contractors leave the carpet gap behind. But some don’t.

So, depending on whether they did or did not consider a carpet during installation, your baseboards may or may not have a carpet gap.

Sagging Floor

The gap in your baseboards may come from a sagging floor. A sagging floor, in turn, may happen for various reasons, which may or may not be serious.

Your sagging floor may be a consequence of house settlement – which is natural. It may also be there because of water damage to your joists and subflooring.

In some cases, a sagging floor comes from the deleterious effects of wood-eating insects on your subflooring and joists.

In severe cases, the sagging floor may come from differential foundation settlement caused by water damage or a poorly constructed foundation.

Working carpenter using circular saw rotating saw cutting wood baseboard

Poorly Cut Baseboard

Your baseboard gaps may just be there because the baseboard was not cut uniformly.

When the gaps in your baseboard come from a poorly cut baseboard, you can detect that readily. The gaps would be irregular in the same way the cut on the baseboard is irregular.

The gaps in your baseboards would most likely be an eyesore. But beyond that, they do not really cause much trouble – they do not affect the structure of your building. Also, fixing them is straightforward.

How to Fix the Gaps in Your Baseboards?

When the Problem Is Foundation Settlement

If the problem is foundation settlement, you should get a professional to assess the situation. Following the assessment, the repair specialist may recommend bracing the foundation, and then raising the floor using screw piles.

When the Floor Joist Is the Problem

If the floor joists are rotten, then sealing the gaps without fixing the rot will not solve the problem.

When the gaps in your baseboards are there because of floor joist issues, you can do the following:

  • Replace the floor joists – If the rot in the floor joists is extensive and severe, the best option would be to replace the floor joists. Trying to patch up the floor joists at such a point or in such a case will only postpone the problem.
  • Patch the floor joists – If the rot in your floor joists has not spread far, a replacement may not be necessary. In such a situation, you could cut the rotten part of the joists out, then treat the remaining wood with chemicals that prevent rotting. Once that is done, attach a new piece of wood in place of the one you cut out.
Engineered wood floor joist on a new custom house framing floor joists

When It Isn’t Structural Damage?

When the cause is not severe or connected to structural damage, you can fix the gaps in your baseboards by doing the following:

Fill the Gap with Caulk

You can fix the gaps in your baseboards by filling them with caulk. This option is ideal when the gap is no more than ¼ inch in size.

If you choose to fill the gap with caulk, ensure you clean out the gap first. When cleaning the gap, make sure you remove dried paint.

Once the gap is free of dirt, apply just enough caulk to fill the gaps. Then smooth the caulk, making it align with the wall.

We recommend using siliconized acrylic latex caulks. They are waterproof and long-lasting. But besides that, they offer an airtight seal, which holds heat in.

There is also paintable caulk out in the market. So, if you intend to paint over the caulk, get one of those.

Fill the Gap with Trim Strips

If you would rather not use caulk, you can use trim strips.

Trim strips are pretty easy to use. They are self-adhesive, and you can readily cut them into the perfect sizes for the gaps.

You can get trim strips in various colors. So, if you shop around, you will find something that matches the color of your wall.

Set of wooden furniture molding

Use Molding

For larger gaps, caulk or trim strips may not be ideal. However, molding should work.

Besides working for larger-sized gaps, molding is perfect for gaps with inconsistent sizes.

While molding is effective for large-sized gaps, your measurement must be precise. When filling baseboard gaps with molding, ensure the size and shape of the molding match the gap correctly.

Impact of Baseboard Gaps

  • If there are gaps in your baseboards, you could be losing heat through that gap.
  • Baseboard gaps are visually unappealing.
  • The gaps can serve as a spot for bugs and lizards to hide in and thrive.


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