The exterior walls of a home serve multiple critical functions. Exterior walls minimize the heat or cool air exchange between the interior and exterior, keep the weather out, and enclose the home’s structure. Besides, exterior walls provide a sound barrier against traffic, planes, and all kinds of outside noises.

The exterior wall width plays an important role in achieving a disaster-resistant and energy-efficient home. But, how thick are exterior walls?

Standard exterior wall thickness is 6-1/2″. Exterior wall thickness is enforced by local construction code. In many areas in the U.S. current code calls for 2×6″ framing with 1/2″ sheathing for exterior walls and 1/2″ drywall inside.

There are different types of exterior walls. Load-bearing exterior walls support vertical loads all the way down to the foundation. In other words, a load-bearing exterior wall carries the structure’s compression loads.

Exterior walls are particularly important in areas prone to natural disasters. The thickness and engineering of exterior walls are must withstand seismic activity and hurricanes. In addition, exterior wall designs require shear wall systems that resist lateral loads (horizontal forces) down to the home’s foundation.

How thick is an exterior wall?

Exterior walls are about 5-1/4 inch thick.

In older homes, most exterior walls are framed with 2 x 4s. But, exterior walls are thicker than that. On the inside, there is sheetrock or drywall. The thickness of the drywall is one inch. And on the outside, there can be a one-inch board with stucco. So the thickness will be closer to about six inches or more.

Here is what makes up the thickness of an exterior wall:

  • Wood frame – Most homes are framed with 2x4s or 3-1/2 inch dressed lumber. But some homes are framed with 2x6s.
  • Inner wall – Drywall or sheetrock is about half-inch thick.
  • Outer wall – Half-inch plywood or chipboard. Also, a siding is nailed to the outer wall, which makes the outer wall thickness about 3/4 inch.

The studding on high-end homes is done with 2x6s, which makes outer walls significantly thicker. So, an external wall with 2×6 inch studding would be about 7-1/2 inches thick.

Thicker exterior walls are more expensive but provide better insulation.

How thick should exterior walls be?

Exterior walls should be about 6-1/2 inches thick. The current code calls for a minimum of 2×6 inch framing with a 1/2 inch sheathing for exterior walls and a 1/2 inch drywall on interior walls.

How thick are wood-framed exterior walls?

Wood-framed exterior walls are 6-1/2 inch thick. The framing is done with 2×6 inch lumber, but on older homes, you will find 2×4 inch framing. Add a 1/2 inch sheathing for exterior walls and 1/2 inch drywall on the inside.

How thick are exterior walls?

Most U.S. exterior walls are 6-1/2 inches wide, but the thickness varies. In older homes, you will find that 2x4s are used for exterior walls, which make exterior walls significantly thinner.

On residential exterior walls, there is 1/2 inch of drywall on the inside and outside.

For example, an exterior wall with 2×4 inch framing, with a 1/2 inch of stucco finishing on the exterior, and 1/2 inch drywall on the inside gives you a thickness of 5 inches.

Why are exterior walls thicker than interior walls?

Exterior walls are thicker than interior walls to provide structural support, insulation and protection from the elements.

Thick walls may cost more, but they offer more benefits. Exterior walls are built thick to act as sound barriers and slow the transfer of heat or cold. In other words, thicker walls give your home a sense of protection from the elements.

Exterior walls are thicker than interior walls because they provide extra insulation. It’s the extra thickness that allows for insulation.

Beyond insulation, external walls need to be made thicker to support the structure it encloses. The bulk of the home’s structural weight is placed on the outside walls, so making them thicker will provide much more structural support.

Typical external wall thickness

A standard exterior wall will be timber-framed with drywall or sheetrock on both sides of the wall.

The basic components of an external wall:

  • External – 1/2 inch drywall, plywood or chipboard
  • Internal – 3-1/2 inch 2×4 timber framing
  • Internal – 1/2 inch drywall

How thick are exterior walls in mm?

Exterior walls should be 254 mm thick. In other words, a one-story building shouldn’t have an exterior wall under 245 mm.

Exterior wall thickness in inches

Standard exterior wall thickness is 6-1/2 inches. But, most importantly, exterior wall thickness is enforced by the local building code. The thickness of exterior walls is influenced by a wood frame, outer drywall, plywood or chipboard and inner drywall.

Exterior wall thickness with siding

Exterior wall thickness with siding is 6-1/2 inches.

Exterior wall thickness 2×6

The exterior wall thickness of 2×6 timber is 6-1/2 inches.

Exterior wall thickness commercial

The exterior wall thickness of commercial buildings starts at around 6 inches and can go up from there to 8 inches, 10 inches, or as thick as needed.

The higher to load, the thicker the exterior walls need to be.

How thick should exterior Aerated Concrete walls be?

A single-story house in a warm climate region would require 12 inches (300 mm) thickness. And the same exterior wall thickness of 12 inches (300 mm) would be sufficient for summer kitchens.

The walls of garages and smaller structures would need 8 to 12 inches (200-300 mm). Such wall width will fully withstand the load from the roof of a small span.

But, the exterior walls of basements require thicker external walls. So, the exterior walls of a basement should have walls between 12 to 16 inches (300 and 400 mm).

Aerated concrete blocks are widely used in the construction of private homes. The high self-supporting capacity of this building material allows for the construction of homes up to 5 floors.

The aerated concrete grade indicates its density – from 662 to 2646 lbs or 300 to 1200 kg / m³. The lower the indicator, the better the thermal insulation properties are, but the lower the material’s strength.

How thick should the exterior walls of Foam Block be?

The thickness of the exterior walls of foam block should be 16 inches or 400 mm. And the insulation on residential buildings will add additional thickness to the exterior walls. Mineral wool, expanded polystyrene, or cladding with bricks is used.

Foam concrete blocks are made from foam concrete. The foam blocks acquire structure during the production process due to additives that induce the formation of tiny closed pores.

Foam concrete is inferior to aerated concrete in terms of strength and thermal insulation properties. But, its specific gravity is higher, and its thermal conductivity is higher.

Foam blocks are laid on a cement-sand mortar, leading to uneven heat transfer through the walls and the formation of cold bridges.

The exterior walls of garages, smaller structures, and premises only used when it’s warm outside don’t require insulation. But because of the low frost resistance of the material, the exterior surface of the wall must be protected with plaster.

How thick are the exterior walls of a tiny house?

The exterior walls of a tiny house will be about five inches. The thickness of the exterior wall is made up of the following:

  • Interior drywall – 1/2 inch thick
  • Wall framing (2×4 inch timber) – 3-1/2 inch thick
  • Sheathing – 3/8 inch thick
  • Siding – 3/4 inch thick

In Closing

The thickness of exterior walls can vary greatly. A brick building might have 24-inch exterior walls, and a mobile home would only have a two-inch exterior wall.

In most houses, interior walls are 4 1/2 inches thick, with a 2×4 stud (3 1/2 inch) + 1/2 inch drywall on each side (inside and outside). Exterior wall thickness will vary depending on where the house is built.

In Florida, most homes are built with concrete block exterior walls. These exterior walls are built with 8-inch blocks, 1/2 inch stucco coat, 3/4 inch furring strips, and 1/2 inch drywall. Which makes the total exterior wall thickness 9 3/4 inches.

In Colorado, on the other hand, house exterior walls are built with 2×4 studs with 1/2 inch drywall and 3/4 inch siding. The total exterior width in such a construction is 4-3/4 inches.

In newer homes, some builders use 2×6 exterior walls when the main floor has higher ceilings over 8 feet. This total width would be 6-3/4 inches.

Exterior wall thickness varies depending on local building codes, structural needs, climate, and seismic activity. Generally, homes are built with a “double-wall” method. A double wall will consist of oriented strand board (OSB) or plywood sheathing on the exterior of the wall over 2×6 studs and 1/2 inch drywall on the interior.

This total thickness would generally net out at 6 and 9/16 inches and is what would be used when ordering your windows and doors.

Firewalls are walls that separate the home from the garage. These walls require fire-resistant drywall, which is 5/8 inches thick and can be applied to either a 2×4 or 2×6 wall separating the house from the garage, depending on the architect’s specifications.

This would result in a jamb size of either 4 and 11/16 inches for 2×4 walls or 6 and 11/16 inches for 2×6 walls. The added 1/16 inch to all the dimensions allows for the growth of wall thickness. As layers of wall covering such as sheathing and drywall are added to the wall’s surface, it widens.

Exterior wall thickness is important for safety and energy efficiency. But, it also has a lot to do with personal preference. Some people take extra comfort in thick exterior walls.