Load-Bearing Wall Calculator

"Can I knock this wall out?" That question launches a thousand renovation projects, and a fair number of expensive mistakes. Before you swing a sledgehammer, you need to determine whether the wall carries structural load from above or simply divides rooms.

Check the direction of floor joists. Look in the basement or attic. If joists run perpendicular to the wall and either lap over it or bear directly on it, the wall is almost certainly load-bearing. Joists running parallel to the wall usually mean it is a partition.

Check for a wall directly below. Load paths are vertical. If there is a wall, beam, or column in the basement directly below the wall in question, loads are likely transferring through it down to the foundation.

Check the location. Exterior walls are nearly always load-bearing. Interior walls running along the centre line of the house (parallel to the ridge) are load-bearing more often than not. Walls running perpendicular to the ridge in the centre of the house may or may not carry load depending on the floor framing layout.

When in doubt, assume it is load-bearing. The cost of a structural engineer's assessment ($300–$600) is trivial compared to the cost of repairing a sagging floor or cracked ceiling from an improperly removed bearing wall. Prices and rates on this page are our own estimates as of the date shown; they change often. Enter your own figures for a current result. For a more detailed walkthrough of the visual clues, read the guide on how to tell if a wall is load-bearing.

Every load-bearing wall supports a strip of floor and roof on each side called the tributary area. Think of it as the zone of influence — the portion of the structure that would collapse if the wall vanished.

For a typical residential layout with joists spanning across the house, the tributary width on each side of a centre bearing wall equals half the joist span. If your floor joists span 14 feet from the exterior wall to the centre wall, the tributary width is 7 feet. The wall carries load from both sides, so the total tributary width is 14 feet.

The loads within that tributary strip stack up: roof dead load (the weight of sheathing, shingles, and framing) plus roof live load (snow in cold climates, minimum code live load in warm ones), plus each floor's dead load (10 psf) and live load (40 psf per IRC Table R301.5), plus the self-weight of the walls between floors (8 psf for wood or steel studs with 1/2-inch drywall both sides). This calculator adds them all up and converts the result to pounds per linear foot (plf) of wall — the key input for sizing the replacement beam.

Those three figures do not rest on the same footing. The 40 psf floor live load is a code cell, printed unamended in the adopted residential codes of Seattle, Texas, Connecticut and Virginia. The 10 psf floor dead load is the span-table design basis that both the American Wood Council's span-table tutorial and the HUD Residential Structural Design Guide state. IRC Section R301.2.2.2 (2021) sets that same 10 psf as an average dead-load limit for floor assemblies. The limit belongs to the code's seismic (earthquake) provisions, so it covers only the buildings that Section R301.2.2 names. Those are townhouses in Seismic Design Categories C, D0, D1 and D2, and detached one- and two-family homes in D0, D1 and D2. The 8 psf wall figure is the weak one: it is a row of ASCE 7 Table C3-1, a paywalled standard this site has not opened, and we have it second-hand from Boise Cascade technical notes GE-1 and GE-22 and from municipal weights-of-materials handouts that reprint the same row. Published figures for that assembly run 6 to 8 psf, and the same seismic section limits an interior light-frame wood wall to 10 psf, so the 8 ships as the conservative end of the published spread rather than as a confirmed value. IRC Section R301.4 asks for the actual weights of the materials in your building, which is what an engineer will use.

Glulam, steel and built-up prices are this site's own figures as of March 2026, not national averages; the LVL row uses this calculator's November 2026 rate. Steel prices are particularly volatile — get a current quote from your steel supplier.

The glulam, steel and built-up per-foot prices above carry no citation. This is our own estimate; no published source backs these figures. Check your results against your product data or a licensed professional before acting. The LVL row is the exception: it and the calculator's own beam-cost output use $1.83 per foot per inch of depth for a two-ply LVL, from one supplier's listed price of $8.69 per linear foot for a single 1-3/4 x 9-1/2 inch ply (Sutherlands, one Kansas City store, November 2026); prices vary by store and region.

For steel beam sizing with precise section modulus calculations, size W-shapes for the span after you know the total load from this page.

This tool gives you a planning-stage estimate so you can budget intelligently before hiring a structural engineer. It uses simplified assumptions that work reasonably well for standard residential framing: uniform loads and simple span conditions.

Real buildings have complications that change the math. Point loads from posts above, offset bearing points, cantilevered balconies, heavy tile roofs, or concentrated loads from upper-floor bathtubs can all increase the required beam size beyond what a uniform-load calculation predicts. An engineer also checks deflection limits (the beam might be strong enough but bounce too much), lateral bracing requirements, and the adequacy of bearing posts and footings at each end of the new beam.

The cost of a structural engineer's beam design is typically $400–$800 for a residential opening. That fee buys you a sealed drawing your contractor can build from and your building inspector will accept. Trying to skip this step rarely saves money — it usually costs more when the inspector rejects the work or, worse, when the floor sags six months later.

Once you have beam dimensions from an engineer, plug them into the framing layout tool to figure out the full lumber list for reframing around the new opening.

1. Hire a structural engineer. They assess the load path, size the replacement beam, and specify post and footing requirements. This produces a sealed drawing you submit with your building permit.

2. Pull a building permit. Removing a load-bearing wall is structural work that requires a permit in almost every US jurisdiction. The permit ensures inspections at key stages — skipping it can create legal and insurance problems when you sell the house.

3. Install temporary shoring. Before removing anything, the contractor builds temporary walls on both sides of the bearing wall to carry the load while the beam goes in. Shoring must be engineered for the actual load — improvised supports with random lumber can fail.

4. Remove the wall. With shoring carrying the load, the existing studs, plates, and drywall come out. The top plate is the last piece removed because it is directly under the joists or trusses.

5. Install the beam and posts. The new beam slides into position, supported by posts at each end (and sometimes mid-span). Posts bear on footings that may need to be poured or reinforced in the basement below. The engineer's drawing specifies all of this.

6. Remove shoring, patch, and finish. Once the beam is secured and inspected, temporary shoring comes down. Drywall, trim, and flooring are patched to close the wall cavity. Plan your drywall quantities for the repaired ceiling and any new soffits around the beam.