How Thick Are Exterior & Interior Walls?

You must have a few questions concerning the exterior and interior walls if you’re building a new house or any other project. During construction, people often guess wrong about how thick the walls inside and outside the project are.

Because of their different purposes, exterior and interior walls need different thicknesses. The debate over how thick exterior and interior walls should be continues. Let’s have a look at what we can find out.

How thick are exterior walls?

When it comes to wall thickness, exterior walls are thicker than interior walls. Because they are often needed to support load-bearing pillars. Exterior walls are also more exposed to the weather. Because of this, exterior walls are typically 8 to 10 inches thick.

Residential home’s exterior walls

A residential home’s exterior walls are typically thicker than any other structure’s interior walls. It’s no different when it comes to private homes.

The thickness of a residential structure is particularly essential since it reveals the overall structural strength.

Exterior walls in residential buildings are often 10 to 12 inches thick. This thickness might vary depending on the kind of plaster or panels used to cover them.

Building exterior walls

A lot of factors influence the thickness of a building’s exterior walls. The climate, the height and material of the walls, and a lot of other things are all taken into account.

Most structures of exterior walls are at least 12 inches thick. If the structure is going to hold a lot of weight, the thickness needs to be changed.

Commercial exterior walls

Commercial exterior walls are not very thick since the materials used influence the thickness of the wall. Commercial construction is often made of high-quality materials. They’re strong and can handle a lot of weight.

Commercial building exterior walls typically range in thickness from 7.5 to 10 inches. In such constructions, this thickness is enough to sustain the enormous loads.

For exterior walls, brick is a popular choice. They are rather affordable when compared to many other building alternatives. Brick walls may also support a substantial amount of weight.

The minimum thickness for brick walls is 9 inches, but there is no maximum thickness. Depending on the design, a brick wall may reach a thickness of 12 inches.

Exterior concrete walls

Concrete walls are fairly strong in terms of structural strength. As a result, concrete barriers don’t need to be particularly thick to be effective.

If there are no additional beams or pillars to support the wall, it must be thick enough to sustain the loads.

Concrete foundation walls are typically 6, 8, or 10 inches thick. The thickness of the wall is determined by the kind of support it has.

Exterior glass walls

Many building projects currently are said to have exterior glass walls. These walls are mostly for aesthetic purposes since they are not the best choice for supporting large loads.

Because they are not meant to sustain weight, glass walls are often much thinner than standard wall thicknesses. In commercial structures, glass walls are typically 1/4-inch to 1-inch thick.

Vinyl siding exterior walls

Vinyl siding exterior walls are normally eight to ten inches thick. When more vinyl siding is added to these walls, the total thickness of the walls goes up a little bit.

A decent grade of vinyl wall siding is approximately 0.4 inches thick. The thickness of the sidings increases as the quality and durability of the sidings improve.

As a result, vinyl siding exterior walls are rough 10-inches thick, where the wall is 8 or 9 inches thick and the vinyl siding is 1-inch or 1.5-inch thick.

What is the thickness of the interior walls?

Interior walls are often thinner in thickness. There are no loads or bad weather conditions on the interior walls. As a consequence, interior walls are generally 4 to 6 inches thick as a result. They are also roughly 8 inches thick if they have plumbing.

Interior walls in a residential home:

The interior walls of most residential houses do not support any of the building’s loads. As a result, many individuals choose to stay thin to save money. Interior walls, on the other hand, must meet certain thickness requirements.

Interior walls in residential construction are frequently 4 inches thick. This thickness may vary based on the material and plaster used.

interior walls with plumbing

Building extremely thick interior walls with plumbing is a waste of money. More wall space for plumbing, on the other hand, is not a bad investment. Instead, it’s a unique way to arrange your space.

Plumbing walls are thicker than typical walls on the inside. This kind of wall is usually 6 to 8 inches thick. It has the potential to extend up to 12 inches at times.


Drywall, often known as plasterboard, is an interior wall covering made up of two layers of thick paper sandwiching gypsum. They are long-lasting and durable. That is why they are so light in weight.

The average thickness of drywall is 0.5 inches. The overall thickness of an interior wall varies from 4.5 to 5 inches when drywall paneling is put over it.

Commercial interior walls

Commercial buildings provide a range of roles, depending on the demands of the clients. As a consequence, commercial buildings’ interior walls vary. However, they are often thicker than typical home interior walls.

Commercial interior walls are typically 5.5 to 7.5 inches thick. The peaceful, professional ambiance of the rooms is enhanced by this thickness.

What are the minimum and maximum thickness of the interior walls?

Internal wall thickness is often less thick than exterior walls. Since they don’t have to hold up the weight of the building, interior walls are often thinner.

When not bearing any weight, internal walls must be at least 4.5 inches thick. If there are any internal plumbing chambers, their thickness will increase to 6 inches. However, if the walls are load-bearing, they must be at least 8 inches thick.

Internal walls, on the other hand, maybe as thick as 8 inches thick, incorporating plumbing and additional plaster. Anything thicker than this is a waste of time.

The thickness of a wall, whether it’s an exterior or interior wall, is important. It is required for the building’s security. As a consequence, while building walls, make sure the thickness is adequate for use. However, avoid building walls that are too thick.

What are the minimum and maximum thickness of the exterior wall?

External walls, unlike inside walls, are subjected to all forms of weather. They are the ones who must bear the structure’s weight. That is why, in general, exterior walls must be thicker than interior walls.

The thickness of external walls should be at least 10 inches. This thickness is enough to withstand almost any harsh weather.

If the outside wall has a hole for more insulation or plumbing, the thickness could be increased to about 11 inches.

Outside walls will have plaster and additional protective coatings in addition to the 10-inch minimum thickness. As a result, the wall thickens even added. The maximum thickness of an exterior wall is between 11.5 and 12 inches.

If your exterior walls have extra insulation or a plumbing cavity between them, the maximum thickness will go up.

What is the appropriate insulation thickness for exterior walls?

The thickness of wall insulation is determined by the needed R-value. R-38 is the lowest R-value that may be used. This R number must be used to estimate the thickness of your exterior walls.

To some extent, exterior wall insulation is more important than interior wall insulation. because the exterior walls are continually exposed to the hot summer sun and the elements outside. As a consequence, exterior walls will need more insulation.

To get the industry-standard R-value of R-38, you’ll need to use 12-inch thick insulation. A majority of the heat from the outside environment will be absorbed by this layer.

If you want a higher R-value, such as R-49, you’ll need to thicken the exterior walls even further.


The purpose and thickness of exterior and interior walls vary. To withstand enormous weights, interior walls are 4 or 6 inches thick, while exterior walls are 10 or 12 inches thick. Thick walls are built of large load-bearing materials, whereas interior walls are thin.