Free Tool
Lintel and Header Size Lookup
Find the sawn lumber lintel needed over a door or window opening from the Ontario Building Code lintel span tables. Choose the species, what the wall carries and the opening width.
Lintel and Header Size Lookup
Result
Maximum span by lintel size
Preliminary planning only. This tool does not replace the drawings. The designer or engineer of record and the building permit set govern every size, span and detail.
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Where the numbers come from
- Source. Tables 9.23.12.3.-A (Douglas Fir-Larch), 9.23.12.3.-B (Hem-Fir) and 9.23.12.3.-C (Spruce-Pine-Fir) of the 2024 Ontario Building Code, No. 1 or No. 2 grade, non-structural sheathing. Values are read directly from the tables. The glued-laminated table, 9.23.12.3.-D, is not included.
- Scope. Article 9.23.12.3. applies to buildings of residential occupancy, where the wall studs exceed 38 by 64 mm, where supported joists span not more than 4.9 m and where trusses span not more than 9.8 m.
- Lintel size. Each size is two pieces of 38 mm lumber on edge, such as 2-38 x 184 (two 2x8s). A single piece of 89 mm lumber may be used in place of two 38 mm pieces (table note 2). Two or more members are nailed together with 82 mm nails in a double row, not more than 450 mm apart in each row (Article 9.23.12.2.).
- Adjustment applied. Only the reduction in table note 3 is applied, when you tick the full width box. The table also allows increases for structural sheathing, shorter joist spans and similar cases. Those are not applied here, so the result stays on the safe side.
- Bearing. Table note 4 asks for a bearing length of at least 38 mm for lintel spans up to 3 m and at least 76 mm for spans over 3 m where the ends of the lintel are fully supported by walls.
- Walls with 38 x 64 mm studs. Sentence 9.23.12.3.(2) sets different rules, with lintels at least 50 mm deeper than the table. Those walls are not covered here.
This tool is for preliminary planning. Header size is a structural decision. The designer or engineer of record and the building permit set govern.
Frequently asked questions
What is a lintel?
A lintel is the beam over a door or window opening in a loadbearing wall. It carries the load from above to the studs at each side of the opening. In many drawings the same member is called a header.
Which load case do I choose?
Choose what the wall above the lintel supports. A wall carrying the roof and ceiling only is the lightest case. A wall that also carries one, two or three storeys of floors is heavier and gives shorter spans. The drawings show what each wall carries.
Why is there no exterior value for limited attic storage?
The table gives values for interior walls only in that row. It is left blank for exterior walls.
What if the floor joists span the full width of the building?
Note 3 to the table reduces lintel spans by 15 percent for roof, ceiling and one storey, 20 percent for two storeys and 25 percent for three storeys where the floor joists span the full width of the building without support. Tick that box and the tool applies the reduction.
Are LVL and steel beams covered?
No. This tool covers the sawn lumber lintels in Tables 9.23.12.3.-A to C. Engineered beams, glulam and steel beams are sized by the designer or from the manufacturer's tables. See the structural beam installation page.
Is this a quote?
No. It is a planning tool. Contact us with your plans and we will arrange a free site visit.
For rough opening sizes, read Window and Door Rough Openings.
Related: Window and door opening framing, Load bearing wall removal, Structural beam installation.
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