Interior Wall Construction: Thickness of Load & Non-Load Bearing Walls

Walls either enclose or divide a building. That is why we have exterior and interior walls. And in a home, it doesn’t just have enough walling that’s important; your walls must have the right thickness too. Most laypeople undertaking construction wonder, how thick should walls be?

Here’s what I know from inspecting house’s walls for decades:

A residential house’s interior walls should be a minimum of 4 1/2 inches. In modern construction, the framing 2×4 wall studs measure 3 1/2 inches wide plus 1/2 inch drywall on both sides, totaling 4 1/2 inches. Interior walls containing plumbing pipes are constructed from 2×6 dimensional lumber rather than the 2×4 wall studs. The framing 2×6 framing measure 4 1/2 inches wide plus 1/2 inch drywall on both sides, totaling 5 1/2 inches.

This guide will look at the interior walls used in construction and how thick each should be.

What Is The Standard Wall Thickness For A House?

The standard wall thickness for a residential house for two by four studs is 4.5 inches, including a half-inch drywall. You should use two by six studs on walls with plumbing, which will bring the thickness to 6.5 inches, including the half-inch drywall.

If you’re new to interior walling, terms such as studs and drywall can be quite confusing. To get a better picture of how walls are measured, it’s best to get at least an overview of an interior wall’s components.

A non-load-bearing interior wall features the following elements:

A Top Plate:

It is a horizontal plate connecting the wall to the ceiling and the vertical studs. It can be a double top plate if your ceiling is 8 feet and above.

A Bottom Plate:

It is also a horizontal lumber plate that connects the wall to the floor. It is usually inexpensive wood like hemlock or pine. 

The lower studs on the partition wall rest on the bottom plate.

Drywall:

The drywall is a panel featuring calcium sulfate dihydrate that packs the sides of interior walls. It also features ceilings.

It is also called wallboard and is used as a finishing material to dress the naked walls. 

You can paint over drywall and sand it for a smooth facade. It is also more stable compared to plaster, meaning you do not have to keep reapplying.

Studs:

Studs help to frame the interior walls as well as provide support. They cover every part of your construction, from interior walls to windows, doors, and exterior walls.

Interior Load and Non-load Bearing Walls Explained

The thickness of a non-load-bearing interior wall is determined by whether or not there are plumbing pipes running in the wall cavity. A load-bearing interior wall will be 6.5″ wide, including the drywall. All exterior walls are load-bearing and will be 6.5″ wide.

I gathered information on the most common materials used for interior walls and their average thickness.

1. Load Bearing Walls

Load-bearing walls carry slabs and beams and transfer the weight to the foundation. These are the walls that make a structure sound. 

A load-bearing wall can be an interior or exterior wall. Interior walls running perpendicular to the ceiling framing are considered load-bearing. These are some of the interior and exterior load-bearing walls to expect in construction and how thick they should be:

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Wood Walls

Wood interior walls will run perpendicular to the ceiling structure. Wood-framed load-bearing walls are typically found in the center portions of the house. The load-bearing walls are constructed from 2×6 lumber that is 5.5 inches wide; 6.5 inches wide with drywall is installed.

Masonry Walls

A masonry wall features materials cemented together using mortar. These are the most durable walls in any structure. The binding mortar restricts the cemented materials like concrete and brick, among others, from falling apart.

A load-bearing masonry wall typically features concrete blocks or bricks as the construction material. These walls should be at least 10 inches in thickness on a 35-foot wall. As the wall increases in height, so should the thickness.

Interior masonry walls can be as thick as 8 inches for houses of less than three stories. External masonry walls, on the other hand, will be as thick as 12 inches.

Precast Concrete Walls 

These are walls constructed when concrete is cast in a wall mold and then cured to strengthen it. The precast wall is ready for installation in the house without the mess of mortar and laying concrete stones.

Precast walls make soundproof interior walls in offices, hospitals, apartment buildings, and hotels, among other places, 

Precast concrete walls fall into three categories:

  • Solid
  • Thin-shell
  • Sandwich

Solid precast concrete walls should have a typical thickness of 4-12 inches. Thin-shell walls should be 5-12 inches thick, including 1-4 inches of insulation.

Sandwich precast concrete walls should also be 5-12 inches thick, including the 1-4 inch insulation. 

5-8 inches in thickness applies to interior precast concrete walls, and 8-12 inches applies to exterior walls. 

Stone Walls

Stone Walls are typically considered stone structures. They are usually thicker than other walls and extremely hard.

But, you can install a thin stone wall system of between 3 and 8 inches as interior walls. The thinner the wall, the less load it can bear and vice versa. 

If you want the interior stone wall to be load-bearing, use more robust material. Even if the wall is thin but features strong material, it can take a certain amount of weight.

For example, granite stone is more robust than limestone. 

Exterior stone walls have traditionally been as thick as 18 inches. But it can be just as effective with a thickness of 12 inches.

2. Non-load Bearing Walls

These are walls that partition spaces in the building. That means they do not carry the weight of the beams, slabs, or floors above them, so they cannot be used as exterior walls. They include:

Aggregate Concrete Walls

Aggregate blocks walls feature concrete and aggregate. They can be hollow or dense, ultra-lightweight, or lightweight. 

Interior walls featuring aggregate concrete should have a thickness of 3 inches. This material makes affordable and durable partition walls that offer acoustic insulation, secure background for fixtures, thermal insulation, and impact resistance.

Wood Walls

Wood interior non-load-bearing walls will run parallel to the ceiling structure. Wood-framed non-load-bearing walls are constructed from 2×4 lumber that is 3.5 inches wide; 4.5 inches wide with drywall is installed.

Non-load bearing walls that may contain plumbing pipes will also be walls are constructed from 2×6 lumber that is 5.5 inches wide; 6.5 inches wide with drywall is installed.

Glass Walls 

Glass walls are a favorite because they are visually appealing while remaining effective as interior walls.

Many people love glass because it allows natural light to flood your space, enabling you to experience the benefits of daylight.

A flat glass that works as an interior wall should be ⅜ to ½ an inch in thickness. You can go as thick as ⅝ inches for a heavier partition.

Ensure that it is architectural glass which is allowed as a building material. Any other glass is not structurally sound to work as a partition wall. 

What Is The Minimum Wall Thickness?

An interior wall should be at least 4 inches in thickness. If the wall features some plumbing like sinks, showers, or pipes, it should be thicker within the range of 6 to 8, even 12 inches depending on the type of building.

Making walls too thick is wasteful, and if they are too thin, they are dangerous.

Load-bearing interior walls should be at least eight inches. 

On exterior walls, the minimum thickness should be 10 to 12 inches. That is because the exterior walls bear the brunt of the building’s load, so they need to be thicker and stronger.

The recommended maximum thickness for a wall going up to 70 feet is 12 inches. And for an additional 70 feet, you have to add four more inches to the thickness of the wall. 

How Far Apart Are Wall Studs?

Stud boards appear 16 to 24 inches along the wall. They are measured from center to center between the top to the bottom of the wall.

Studs hold up the drywall on your interior walls. They are also used on exterior walls to hold up wood sheaths.

If you are looking for a stud, check your electric box or receptacles or the sides of your window.

How Do You Measure The Thickness Of A House Wall?

1. Measuring The Exterior Wall

You can measure your exterior house wall thickness by measuring the casings of the exterior door or window.

During the measurement, remember to include the exterior wall sheathing. It is considered part of the wall.

Other sections make up part of the wall. These include

  • The exterior finish
  • The insulation
  • The exterior wall sheathing
  • Wall studs
  • The drywall on the internal side of the wall
  • The floor joist 
  • The sill plate 

These parts make up the cross-section of the exterior wall. However, professionals only include the exterior wall sheathing as part of the wall when taking wall measurements.

2. Measuring The Interior Wall

To measure an interior wall, you can opt to measure the thickness of the blocks (or alternative material) you will use on the wall. This is applicable if you leave the brick or stone blocks raw and uncovered.

In partitions featuring glass or wood, it can be as simple as measuring the width of the door jamb if it spans the width of the drywall on both sides of the wall and the door frame.

What Is The Average Wall Height For A House?

In the United States, the average wall height for a house is 8 feet. Older homes may be a foot shorter at 7 feet. On the other hand, luxury and custom homes may feature higher walls because they have higher ceilings. 

How Do Thick Interior Walls Impact Your Space?

When considering the wall thickness of your interior walls, you have to consider how that affects the practicalness and functionality of your space.

Advantages Of Thick Interior Walls

1. Accommodates Systems

Interior walls offer a place to place your aquarium and other systems that make the space vibrant and alive. 

The thicker the walls, the heavier the system they can accommodate. They can take the weight of an aquarium or bookshelves.

2. You Can Dress Them

You can also dress thick walls and change the wallpaper or other decorative elements without fear of disturbing its structural balance.

For example, thick stone walls can take pictures, trophy cases, paintings, and other interior design elements. Thin plywood walls may sag when you place heavy items on them or split when you try to nail a picture onto the wall.

3. Provide Insulation

Thick walls have more room for insulation, making the house cozy and warm, especially in cold weather. 

Also, you can put acoustic insulation into the wall to make your space soundproof. 

At the same time, thick walls allow you to create space for in-wall storage and deep sills. 

Disadvantages Of Thick Interior Walls

1. Limited Light

The thicker the wall, the harder it is for light to penetrate through. Some materials are impenetrable, like stone and concrete. Other options like glass can allow light in.

However, if you choose very thick glass, it will limit the amount of light flowing through compared to a thinner glass.

As a result, the house looks dark, cold, and uninviting because no natural light flows in. You may feel like you are living in a cave.

In some cases, it may be harder to sell your house if you have very thick walls that limit light pouring in.

2. Poor Aesthetics

A thick, bulky wall may take away from the house’s overall look, depending on the decor you have.

Having thick wall partitions can take away from the modern look that you would otherwise achieve with light, thin wood, or glass partitions.

Thick walls are not ideal if you are looking for a minimalist interior design.

3. Consume Space

Thick interior walls will take up significant space compared to thinner walls. If you have a limited space to build on, that can eat up the little space you have. 

In any building, you want to maximize usable space, and if the walls crowd the house, that is not possible.

4. Prone to Rotting

Thick walls form condensation within as warm air inside them meets cold air from outside. The condensation becomes moisture that begins to rot the insulating boards and frames on the wall.

Before you build thick walls, ensure that you treat any wood elements going into them with borates to prevent rot.

Conclusion

Whether your interior walls are load or non-load-bearing, most municipalities in the United States require you to have a building permit before putting up one. That is because all walls, including interior walls, must be built according to the local building code. 

Check the codes in your locale to find out how to build your exterior and interior walls according to building requirements. But ultimately, the thickness of your walls is a matter of preference.

Sources:

Types of Walls in Building Construction

What is Masonry Wall? 5 Types of Masonry Wall

Instructions on Building an Interior Wall

Thin Stone Wall Systems

How to Build an Interior Wall

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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