Everything You Wanted to Know about Bearing Walls

Many homeowners, would like to open up floor space, especially within older homes which often have relatively small rooms divided by walls. Removing walls however must be done carefully, since some interior walls generally support upper floors and attic floor. Roof framing might also be supported. Walls that support other parts of a building are known as “bearing” walls.

This article describes key concepts of bearing walls as well as details for wood-framed buildings. Basic familiarity with the terminology of wood framing and construction is helpful for understanding, though not essential.

PURPOSE OF BEARING WALL
A bearing wall, also known as a “support wall”, supports other parts (elements) of a building, such as the roof or one or more floors. Downward force (load) is applied, generally to top of the bearing wall, by the weight of supported elements and the weight of any variable (”live”) loads carried by these supported elements.

The term “bearing” refers to the action of the wall as it “bears” (supports) the load from roof, floors and other building elements.

Although “bearing” is due to downward (gravity) loads, some bearing walls have to resist forces acting in other directions. A bearing wall that supports roof framing will also have to resist upward force, from wind uplift pressure applied to the roof surface. Exterior bearing walls also have to resist horizontal force from wind, perpendicular to the wall. Exterior and interior bearing walls may also have to provide “shear wall” capacity, by resisting horizontal force parallel to the wall, especially in areas prone to earthquakes or hurricanes.

The following discussion is strictly for downward loads, although some also applies to walls that must resist forces in other directions. Removal of bearing walls is also addressed.

BASIC CONSTRUCTION
Basic requirements for bearing walls are included in the governing building code, such as the International Building Code (IBC) or International Residential Code (IRC) in the US. However, the building code does not cover details for every case. Bearing walls are constructed using the same materials as other walls.

For a house built with wood framing, bearing walls are constructed with wood studs (most often 2×4 or 2×6), generally spaced at 16 inches along the wall. Double-studs may be installed at various locations, such as at edges of wall openings.

A bearing wall must always have a double top “plate”, which consists of two horizontal lengths of wood (same size as wall studs) across tops of the studs. The double plate provides required strength and stiffness for loads (from above) that are applied between wall studs.

Wall studs bear on a single bottom (or base) plate that most often is on top of plywood floor sheathing (on top of floor joists). The bottom plate must be securely nailed down to the floor joists or other supporting member underneath, such as a wood beam.

LOADS ON BEARING WALL
Most often, the bearing wall supports floor joists (such as 2×8s or 2×10s) or roof framing members (rafters or trusses) that are perpendicular to the bearing wall. Joists and rafters almost always bear on top of the wall.

The wall may also support concentrated (”point”) load from a beam. In that case, double or even triple wall studs may be necessary under the beam where it bears on the wall.

Bearing walls on the first floor often support bearing walls above, on upper floors, in addition to second floor joists. The upper bearing wall might support a third floor, an attic floor or roof framing.

EXTERIOR BEARING WALLS
Exterior walls that support floor joists (including attic floor joists) are bearing walls. However, even if an exterior wall does not support floor joists, it can still be a bearing wall if it supports roof framing (rafters or joists). Identification of such condition requires careful evaluation when floor joists and roof rafters run in opposite directions for a two-story house.

The exterior wall below the second floor is a bearing wall if the rafters (or roof trusses) are perpendicular to the wall, even if second floor joists are parallel to the wall. The lower wall must support load from the roof, as well as load from the outer ends of attic floor joists that bear on the upper wall.

INTERIOR BEARING WALLS
Interior bearing walls (inside the house) generally support floor loads only, not roof loads, although there are exceptions.

Floor joists on opposite sides of a wall can be run in different directions. Therefore, just because inspection on one side of a wall may indicate that a wall is not a bearing wall (since joists are parallel), conditions on the other side of the wall must also be inspected to provide certainty as to the bearing (load-supporting) status of the wall.

Interior walls that are not bearing walls are “partition” walls.

HOW TO LOCATE INTERIOR BEARING WALLS
For a relatively new house, building plans (if available) may identify interior bearing walls. However, as-built framing construction should always be verified visually before any wall is removed. “As-built” construction may be different than the building plans.

For many existing houses with rectangular floor plans, interior bearing walls can often be located by visual inspection. Tools such as stud-finders may be useful to obtain more information about direction of floor joists.

However, ceiling finish must usually be removed to determine with certainty if an interior wall is in fact a bearing wall. For older houses, built before 1950, and for houses with irregular floor plans, ceiling finish should always be removed to verify bearing wall conditions.

For the vast majority of houses built since 1950, a ceiling is up against (attached to) the bottom edges of floor joists, even though some may describe the joists as ceiling joists. For older houses, separate ceiling joists are sometimes found (below floor joists).

A difficult bearing wall condition to evaluate is the case when a lower bearing wall does not support the second floor but does support load from an upper floor or roof. Proper identification of such condition, which most often occurs for older houses, requires careful inspection by a qualified person (usually builder or engineer).

A partial segment of a continuous, straight wall can be a bearing wall while the remainder of the wall is not a bearing wall.

Also difficult to determine is when a floor beam bears on a “built-up” column (several wall studs) within a wall. If only the beam bears on the wall, the remainder of the wall can fairly be considered a partition wall, not a bearing wall.

SUPPORT FOR BEARING WALL
All loads (forces) applied to a building must eventually be transferred, through the structural assembly, to the ground. Comparison to an electrical circuit is often useful for basic understanding of this principle.

Therefore, just as the bearing wall supports other building elements, the bearing wall itself must be supported by other building elements.

A common condition is for an interior bearing wall (on first floor) over a basement. This type of bearing wall is typically about midway between front and back walls of the house, supporting second floor joists. The lower bearing wall may also support another upper bearing wall that supports attic floor joists.

The lower bearing wall (over basement) must have adequate support from a beam (girder) that is supported by columns in the basement. Most often, this beam is directly under the lower bearing wall, although the base of wall will be on top of floor joists that bear on top of the beam.

When a bearing wall is parallel to floor joists, a “floor beam” may have to be installed to support relatively heavy load from the wall, especially if the wall is over a long stretch of basement or crawlspace.

TEMPORARY SUPPORT FOR REMOVAL OF BEARING WALL
Before removing a bearing wall, temporary support (shoring) must be installed to support floor or roof framing that is currently supported by the bearing wall. This requirement is absolutely essential. Otherwise the entire building could collapse.

Temporary shoring typically consists of a wood-stud wall, on each side of the bearing wall. Top of the temporary wall must be tight against wood framing members (not ceiling finish that can crush).

Although a qualified contractor can often install temporary shoring without engineered design, consideration should be given to effects on lower floor framing, due to shifting of loads from the bearing wall (to be removed) to the temporary support walls.

For more articles by this author, please go to Helium.com

John F Mann, PE
Structural Support
1212 Main Street, Suite 2
Belmar NJ 07719
732-556-6080
jmann77@optonline.net

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