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Calculate lintel size and load capacity for masonry openings. Determine bearing requirements, bending moment, and deflection for brick, block, and stone walls with steel angle or concrete lintels.
Total opening: 0.00 ft (0.0 in)
Minimum required: 4"
Enter opening width to get recommendation
Steel angle with bearing plates
0.0" opening + 2 × 8"
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A lintel is a horizontal structural member that spans an opening in a masonry wall, such as a doorway or window. It transfers the weight of the masonry and any loads above (roof, floors) to the supporting walls on either side of the opening.
Lintels are critical structural elements that must:
Lintels must have adequate bearing on the supporting masonry on each side. Insufficient bearing can cause:
Use steel bearing plates under steel angle lintels to distribute load
Full mortar bed beneath lintel for even support and load distribution
Provide shelf angles below lintels for support during construction
Allow thermal movement with sealant or flexible joint
Standard steel angle lintels with typical allowable loads (based on 36 ksi yield):
| Size | Allowable Load | Weight/ft | Common Uses |
|---|---|---|---|
| L2×2×1/8 | 450 lbs | 3.19 lbs | Small windows |
| L2×2×1/4 | 850 lbs | 6.08 lbs | Small windows |
| L3×3×1/4 | 1,400 lbs | 9.4 lbs | Small windows |
| L3×3×3/8 | 1,950 lbs | 13.6 lbs | Windows/doors |
| L4×4×1/4 | 2,100 lbs | 12.8 lbs | Windows/doors |
| L4×4×3/8 | 2,900 lbs | 18.5 lbs | Windows/doors |
| L4×4×1/2 | 3,650 lbs | 24.8 lbs | Large openings |
| L5×5×3/8 | 4,200 lbs | 23.6 lbs | Large openings |
| L5×5×1/2 | 5,450 lbs | 31.8 lbs | Large openings |
| L6×6×1/2 | 7,200 lbs | 37.4 lbs | Large openings |
| L6×6×5/8 | 8,750 lbs | 45.8 lbs | Large openings |
Clear opening of any loose material. Ensure bearing surface is level and solid.
Place steel bearing plates (3"×3"×1/2" minimum) under angle ends with 1/2" mortar bed.
Use shims to level lintel. Verify with spirit level before grouting.
Fill all bearing gaps with grout. Caulk exterior with flexible sealant.
Construct temporary support structure to exact opening dimensions and height.
Place rebar in bottom of lintel (minimum 2-#4 bars) with 2" clearance.
Fill formwork with concrete (minimum 4,000 psi). Consolidate and level.
Allow 28 days for full strength. Remove formwork minimum 7 days after pour.
Steel angles are lighter, easier to install, and cost less upfront but require painting for corrosion protection. Concrete lintels are heavier, maintenance-free, and better for large spans but cost more and require formwork during installation.
Standard minimum bearing is 4 inches for spans up to 4 feet, 6 inches for 4-8 feet, and 8 inches for spans over 8 feet. Always verify local building codes for your area.
Yes, steel will rust if not protected. Paint both sides of the lintel with primer and exterior paint before installation. Some specify hot-dipped galvanizing for additional protection in damp environments.
Wood lintels are not recommended for masonry openings due to decay risk, limited span capability, and structural limitations. Steel or concrete are the preferred materials for masonry support.
An undersized lintel will deflect excessively, bend, or fail under load. This causes cracking above the opening, jamming of doors/windows, and potential collapse. Always use the calculator and verify with local codes.
Signs of lintel failure include cracks radiating from corners of opening, sagging above opening, rust staining, and movement of doors/windows. Have a structural engineer inspect if you observe these signs.
Yes, bearing plates distribute the concentrated load across the masonry. Use minimum 3"×3"×1/2" steel plates under each end of the lintel with a full mortar bed beneath.
Steel angles can be spliced using bolted or welded connections, but this requires structural design. For very long openings, consider multiple angle lintels or a built-up plate girder. Consult an engineer for spans over 20 feet.
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