How Thick Are Exterior Walls On a House?

Learn about the correct exterior wall thickness your house should have

Updated on:

Walls are what keep our homes stable and safe. If you build a house with the walls that are too thin, the entire construction will not be safe and stable enough thus it won’t be able to provide you with proper accomodation.

This is why, whether you are building a home from the ground up, or you are just adding on to your existing house, it is always good to know about the standard thickness of exterior walls. 

See, if the walls of your house are too thick, you will be wasting costly and precious material and space. But if they are too thin, your construction will be allowing the heat and cooling to escape, which means that your home will never be properly cooled during the summer or heated during the winter. And excep for this nuance, such a house will also not be able to support the structure's siding and roof. 

So, how thick should an external wall be? To find the answer and learn more about the house wall thickness, we recommend you read this article. You will not only find out what wall thicknesses is considered proper. We will also tell you what the definition of the wall is, what exterior walls are, and what factors determine the wall thickness of a house. In addition, you are going to find out what materials are most commonly used for house walls making. 

various wall types and thicknesses

What Is the Typical Exterior Wall Thickness?

According to the general rules of home construction, external walls generally should be from 10 to 12 inches wide. Homes that are built with rammed earth or heavy exterior masonry will have thicker walls, of course. But in general, there is no limit to how thick an exterior wall of a house can be. On the contrary, most of the wall thickness will be determined by the framing itself, then the siding material will be tacked on for the final measurement

Why is it so important to take a wall thickness into consideration,  you may be wondering? See, the exterior walls of a house serve several functions that are vitally important: 

  • the walls enclose the structure
  • they keep the weather out
  • hey minimize the heat
  • walls cool air exchange between the interior and exterior of the home
  • exterior walls also provide a sound barrier against outside noises from traffic, planes, etc.

In addiion, load-bearing exterior walls carry the structure's vertical compression loads down to the foundation. And if your house is located in the area that is prone to natural disasters like high seismic activity, hurricanes or tornadoes, exterior wall design must include shear wall systems that resist lateral loads (meaning horizontal forces) down to the foundation. 

The exterior wall width also plays an important role in achieving an energy-efficient, as well as disaster-resistant home with good indoor environmental quality.

What Is Considerde a Wall?

The question will probably seem weird to many of you, but it is essential to understand exactly what a wall is and what it is used for if you want to better realize why its thickness is so important in buildings and especially in homes.

So a wall is any structure that is used for dividing or enclosing a measured space. As you know, walls can be interior and exterior. Interior walls are dividing rooms on the inside of a building. Respectively, exterior walls can be on the outside as well. An exterior wall is any wall that forms part of a building's envelope. It must be all or partially on the outside of the structure, with roof supports attached to its top.

So if you are building a new wall or in case you are extending an existing one, you will want to be sure that certain building guidelines are met. Luckily, the framing of a wall and the drywall that covers it will almost always meet the requirements for thickness. 

So now you know the general rule for your home’s wall thickness, and in addition, we reminded you of what exterior and interior walls are. With that in mind, you will better understand why some of your home walls should be thicker or, on the contrary, thinner than others.

What Factors Determine the Thickness Of the Wall?

The thickness of your home’s walls means a lot in terms of safety and the entire building stability. See, the enclosing structure is a complex engineering structure that has many tasks. It is needed not only for decent protection of the house from various external elements like rain, wind, frost, and solar radiation. It also perceives the load from the ceilings, roofs, and everything that rests on them. 

As for internal walls and partitions, they are used for dividing the space into rooms too. This is why the required wall thickness to support the function in this case will depend on the following factors:

  • the type and properties of the material strength
  • thermal conductivity
  • frost resistance
  • resistance to various kinds of loads
  • installation method
  • the climatic zone where the building is located
  • the minimum and average temperatures during the heating season
  • the amount of solar radiation
  • the strength and direction of the wind
  • the microclimate of the room
  • the required humidity regime

Except for these nuances, you should also take into consideration such aspects as seasonality of use during temporary operation, and the type and number of storeys of the building at the lower level, since the load is much higher there than at the upper one. Combinations with external insulation when using thermal insulation also matter.

So when you consider all these factors and nuances, you will be able to calculate how thick your house’s walls should be, both external and internal, if you aim to build a construction that will serve you for decades.

What Are Exterior House Walls Made Of?

Since the aspect of your home’s exerior walls is so important, as you could already see, you can probably assume that the material they are made of also plays an important role. And if you think so, you are right. 

Exterior walls can be constructed from a wide variety of materials today. Below, you can check out and examine some of the most commonly used types of materials, so that you can get a better idea of what you might want to make use of on your own projects (if you decide to build or rebuild your house, for example).

Cladding Walls

If you are an owner of a building that is in need of a brief outside rehab, then you should definitely take this material into consideration! See, cladding is the type of material that is used for exterior walls in most cases of such kind. In addition, this premade wooden material is easy to install since it is simply affixed to the outside frame of the building, thus giving it a needed look. And since cladding can be successfully used on both homes and other types of buildings, it can be considered universal.

Brick Walls

Brick has been a popular external wall option for centuries, as you surely know. This option is great if your goal is to add some additional insulation to an existing structure. Why is that, you may wonder? See, the bricks are thick enough to withstand extreme changes in outside temperatures, as well as cope with different weather conditions. This is why this material survived through so many years!

Insulated Vinyl

This type of material is the most commonly used on residential homes. The reason for its widespread usage is mostly due to the lower cost in comparison to other common wall materials. Also, insulated vinyl is known for its longevity. And since the material has a relatively low maintenance requirements itself, homeowners often choose it. 

In addition, insulated vinyl has another great benefit: it is very easily installed. All you need to do is to simply affix it to the exterior frame of the building quickly, and it helps the building retain much of the desired internal temperature.


Wood is anoher ype of wall material, along with the bricks, that people have been aware of for centuries, if not thousands of years! Nowadays, wooden siding can come in several types. And all of these types have their own advantages and disadvantages. 

Whether you are working with log, shiplap, or hardy plank, it is essential to keep in mind that wood belongs to the materials that take more skill and time to affix to the side of your building, in comparison to newewr alternatives (such as vinyl or cladding).

As for the lifespan of wooden siding, it will vary depending upon the type of the wood that is used, as well as the climate, and other factors. But with a proper routine maintenance and regular repairs, most types of wood siding can last up to thirty years with minimal issues!


Steel may still sound like a way too odd wall material to many homeowners because it has become a more popular option for external walls in recent years only. However, this material has its perks and benefits! For instance, walls and siding made of steel  are more durable than walls made of other materials. Also, steel walls and siding are stronger, and in addition, they require less maintenance than vinyl or wood, for example. 

Of course, you need to note that steel is more expensive than most types of external walls materials, nevertheless, because of its longevity, you might want to take it into consideraion as well.

Cinder Block

Cinder blocks are used for exterior walls of our homes, as well as for the walls of commercial structures because they are sturdy and stackable. These blocks are fairly thick, which mdeans that they will help insulate the building more than most alternative options allow you to do.

However, that thickness has a downside. The thicker the wall, the more likely moisture will accumulate inside of it. Moisture inside an exterior wall can eventually lead to mold and mildew problems as well as contribute to the slow deterioration of the wall itself.

Now that you know more about the most popular wall materials, it will be simpler for you to figure out which one of them would be more suitable for your building projects, for example. Also, now you will be able to better understand what you should expect from each type of these wall materials in terms of protection, thickness, durability, etc.

Why Are Exterior Walls Thicker Than Interior Walls?

If you have ever had to build or renovate a house, you have probably noticed already that interior walls are way less thick in comparison to their exterior “relatives”. But have you ever wondered why this is like that?

See, exterior walls are thicker because of both structural and insulation reasons. We suggest you take a look at each. Like this, you will be able to get a better and more complete understanding.

If your walls are only made of the siding material and inside drywall, they will only allow a house to maintain so much of its desired internal climate. You might not be aware of this, but cold weather can reach through even the best quality vinyl or wood siding! And they aren't even a close match for hot weather days.

But with the additional thickness, your walls will have a great deal of insulation that they need so much. When installed, the material of the wall helps to keep external temperatures at bay so that they stay away from affecting the inside of a house. Likewise, good insulation also keeps the comfortable climate inside the walls to be more constant.

Also, external walls need to be made much thicker than the internal ones in order to support the structure it encloses. The bulk of the dispersed weight of the structure's roof is placed on the outside walls, so making them thicker will lend much more structural support.

So, this was all that we were going to share with you on the subject of externall home walls thickness. Now we hope that this topic became at least a bit clearer for you, and you will be able to not only understand why your home’s exterior walls must be thicker, bu also, what material would work the best for this purpose.

Publication date: