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How Thick Are The Walls? [Things You Need To Know]

Before building your dream home, what are the things that may come to your mind? One of the first things that cross the mind is how thick the walls should be. It’s super confusing.

But today, we’ve got the answer to your question.

How thick are the walls?

The usual thickness of an interior wall is 4.5 inches. In the case of exterior walls, the thickness is a bit more. The bathroom and basement walls have different thicknesses for distinct purposes as well. Nonetheless, the masonry walls have a different thickness than lumber walls. Two types of masonry walls have different widths too.

That doesn’t completely clear up your confusion, right? We’ve discussed in detail everything you need to know about wall thickness. Read through our article for the details!

Things You Should Keep in Mind about Wall Thickness

There are some general rules of thumbs when it comes to wall thickness. But they may differ depending on some factors. These factors will help you clear up a lot of confusion.

Interior vs Exterior Wall

The exterior wall plays a significant role in supporting the roof and overall insulating your home. That’s why interior walls should always be thinner than exterior walls.

The Climate of Your Area

If you live in a desert or a colder area, the walls should be thicker than usual. But in the case of tropical regions, the walls don’t need to be so thick.

No matter the area, the paints start to peel off if the plasters get old. You’ll have to prime the old plastered walls and repaint them after a few years.

Material of The Wall 

Walls built with more robust materials don’t need to be so thick. But walls made of weaker materials have to be thick enough to support the roof.

How Thick Should Walls Be?

Walls need to be thick enough to hold the structure of your house. Also, to keep you comfortable irrespective of the outside temperature. But too thick walls are not desired either. 

Don’t worry – we’ve got a detailed discussion on this down below:

Interior Wall Thickness

The interior walls are generally built with 2 by 4 or 2 by 6 studs. The 2 by 4 studs are the most common ones. The actual width of a 2 by 4 framings is 3.5 inches. 0.5 inches of drywalls are also added to both sides of the framings.

The total thickness of an interior wall is 4.5 inches. The walls that contain the plumbing and electrical lines will be thicker than usual.

Exterior Wall Thickness

As we said before, exterior walls are wider than interior walls. This gives you a number of benefits. The extra thickness gives your house better insulation, better soundproofing, and a more robust structure.

You can make the exterior wall thicker by choosing a wider framing. Also, you can just simply add layers to thicken up the outer wall.

But don’t make it too thick to avoid fungus and bad lighting problems.

Bathroom Wall Thickness

The 2 by 4 studs are used for framing the bathroom walls, just like the interior walls. But the width of the drywall used in bathroom walls is ⅝ inches. That gives the bathroom walls an extra width of ⅛ inches on both sides.

Here, maintaining the proper distance between the wall and the shower is also necessary.

Basement Wall Thickness

The basement walls should be more insulated than the interior walls. That’s why in the case of basement walls, 2 by 6 studs are used for framing purposes. The actual width of a 2 by 6 stud is 5.5 inches. 0.5 inches width of drywall is also added on both sides of the framing. That makes the thickness of basement walls a total of 6.5 inches.

How Thick Are Walls Made of Masonry?

If you want to make your walls with masonry, then the calculations will be completely different. Don’t be baffled because we’ve got it all prepared for you!

Cavity Walls

The cavity walls have an outer layer, an inner layer, and a space between the two layers. The inner and outer layers both have the width of a brick, which is 3 and ⅝ inches. The space between the two layers is 2 inches wide. In total, cavity walls are 9 and ¼ inches thick. 

If the wall is plastered, you just have to add another ½ inch. These walls provide excellent insulation and protect the house from moisture.

Plastering the walls makes the wall surface smoother and makes it more durable. Here are some of our recommended plasters that you may like-

Product 1
Product 2

Solid Walls

The solid walls don’t have any space. They’re not good insulators and don’t do well in protecting the house from rain. The overall thickness of solid walls is 9 inches. 

But, it’s crucial to seal the space between the foundation wall and slab.

Thickness Limit of Walls

There are usually no thickness limit rules for walls. But that doesn’t mean you can just keep thickening up your walls. The maximum width of your wall should be 12 inches. 

This is if the height of your house is less than or equal to 70 feet. You can add 4 inches more for every additional 70 feet.

Pros And Cons of Thicker Walls

First, we’ll look into the benefits of having a thicker wall. Thicker walls will provide you with good insulation. That way you don’t have to use your heater as much, and it will help you save your electricity bill. Wider walls also give a lot of space in the window sills. You can utilize that space by putting your things there.

The extra thickness will strengthen the structure of the house as well. The thicker your wall, the more soundproof it is. If your home is beside a busy street, thicker walls can help you a lot.

Now let’s look at the problems. Thick walls take up a lot of space. They’re also prone to moisture problems. Moisture gets condensed inside thick walls and attracts fungus and bugs.

But borate treatment can prevent this problem. Bad lighting can be another problem of thick walls if you’re not fond of darker places. Thicker walls give your home a cave-like atmosphere.

Everything about wall thickness should be a lot clearer to you now.


Question: Should exterior walls be framed by 2 by 4 or 2 by 6 lumbers?

Answer: Usually, 2 by 4 studs are most commonly used to construct the exterior walls. But using 2 by 6 studs is an upgrade, and in some places, it is mandatory to use 2 by 6 in exterior walls.

Question: What is the thickness of a 2 brick wall?

Answer: 2 brick walls have a thickness of the width of 2 bricks. The width of one regular size brick is 3 and ⅝ inches. So the total width of 2 brick walls will be 7 and ¼ inches.

Question: Is it a problem to build a 2 story house with 2 by 4?

Answer: No, there’s absolutely no problem if you build a 2 story house with 2 by 4. There are millions of 2 story houses constructed with 2 by 4 lumbers.

Final Words

We hope we were able to clear everything out about how thick are the walls.

Remember to follow the general guidelines while determining the thickness of your walls.

Wish you all the best!