Design a Wood Beam, Joist, and Girder to CSA O86

CanadaCSA O86:19NBCC 2015CWC Wood Design Manual 2017

Wood Beam

The easy to use online Calcs.com Wood Beam Calculator to CSA O86:19 enables you to do quick and powerful design and analysis for simple and continuous timber beams, with unlimited supports and loads. Choose from our library of thousands of common wood sections, or create your own and get instant results with our easy to understand traffic light checks for moment, deflection, and shear.

The Calcs.com Wood Beam - Generic Beam, Joist, and Girder Calculators allow you to quickly design wood horizontal members. In this article, a worked example comes first, followed by an explanation of each section of the calculator. The Wood Beam Calculator has 4 main sections

Key Properties
Loads
Design Conditions
Summary and Graphs

Worked example

Example 1: simply supported beam

A simply supported glulam beam spans 4 m under a dead load of 10 kN/m and a live load of 15 kN/m. The steps below use the conditions in the image.

Example Beam #1, simply supported: a 4000 mm beam on a pinned support at the left and a roller support at the right, each with a 75 mm bearing length, under a dead load G of 10 kN/m and a live load Q of 15 kN/m, with a glulam Douglas Fir cross-section. Conditions listed: glulam Douglas Fir, pinned left and roller right, 75 mm bearing length, no continuous bracing, self-weight included, dry service conditions, untreated, no load sharing.

The conditions are:

Length: 4 meters
Member type: Glulam, Douglas Fir
Supports: Pinned and roller support on the left and right respectively, 75 mm bearing length
Bracing: No continuous bracing
Loads: 10 kN/m dead load and 15 kN/m live loads along the strong axis
Self-weight included
Dry service conditions, untreated with no load sharing

Open the Generic Beam preset

In your project, choose Add New Calculation, select CA, choose Wood Beam under Beams, then choose Generic Beam.

Add a new calculation window for Canada with Wood Beam selected under Beams and its eight presets listed below, starting with Generic Beam.

Check the member

The Generic Beam preset loads with 7x13.5 [175x342] 24f-E D.Fir-L, a glulam Douglas Fir-Larch section, so leave it as it is. To find it in the list, choose Select… under Size and Grade, set Type to Glulam and Species to Douglas Fir-Larch, and type 7x13 in the search box.

Size and Grade dialog with 7x13 typed in the search box, Type set to Glulam and Species set to Douglas Fir-Larch, listing six 7x13.5 [175x342] sections with the 24f-E D.Fir-L row ticked and a utilization badge for each check.

Set the beam length

Enter 4000 mm for the Beam Plan Length. The Total Material Length shows 4000 mm. Number of Plies stays at 1, and Continuous Bracing for Lateral Torsional Buckling stays at No continuous bracing.

Key Properties section with the 7x13.5 [175x342] 24f-E D.Fir-L section, one ply, a Beam Plan Length of 4000 millimeters, a Total Material Length of 4000 millimeters, and No continuous bracing.

Set the supports

In the Supports and Braces table, the first support is Pinned at 0 mm. Change the second support to Roller at 4000 mm. Enter a bearing length of 75 mm for both.

Supports and Braces table with a Pinned support at position 0 millimeters and a Roller support at position 4000 millimeters, each with a bearing length of 75 millimeters, below the Continuous Bracing dropdown showing No continuous bracing.

Remove the preset's distributed load

The preset adds a Floor Load row in the Distributed Loads table. Select the menu on the right of the row, then Delete row.

Distributed Loads table with the Floor Load row menu open, offering Duplicate row and Delete row.

Add the line load

In the Line Loads table, enter 0 mm for the Start Location and 4000 mm for the End Location.

Line Loads table with a row with a Start Location of 0 millimeters and an End Location of 4000 millimeters, and an empty Load Magnitudes cell with an Edit link.

Enter the line load

Select Edit… on the row. In the Load Magnitudes window, enter 10 kN/m for the start and end magnitude of the (D) Dead Load, and 15 kN/m for the start and end magnitude of the (L) Live Load. The (Lr) Roof Live Load stays at 0.

Load Magnitudes window for a line load with the Dead Load at 10 kilonewtons per meter at the start and end, the Live Load at 15 kilonewtons per meter at the start and end, and the Roof Live Load at 0.

Check the rest of the loads

The load diagram now shows the line load and the self-weight on the 4 m beam, and the Distributed Loads table is empty. Bending Axis stays Strong (X-X), Include Self-weight stays Yes, and Load Direction When Linking to Column stays Axial (Ny).

Loads section with a load diagram of the 4 meter beam showing the line load and the self-weight, an empty Distributed Loads table, and the Line Loads row from 0 to 4000 millimeters, with a roller symbol at the right support.

Bending Axis set to Strong (X-X), Include Self-weight set to Yes, and Load Direction When Linking to Column set to Axial (Ny).

Check the design conditions

The preset already has Dry for Service Condition, Untreated for Treated, and No System Factor. Storage Live Load and Consider Shear Deflection are No, the deflection limits are 25 mm absolute, 360 for live and short-term, and 240 for long-term, and Double L for cantilevers is Yes. Leave them as they are.

Design Conditions section with Service Condition set to Dry, Treated set to Untreated, System Factor set to No System Factor, Storage Live Load and Consider Shear Deflection set to No, deflection limits of 25 millimeters, 360 and 240, and Double L for cantilevers set to Yes.

Read the results

The Summary lists the factored bending moment, shear and bearing demands with their resistances, the governing deflections, and a utilization badge for each check. The Reactions diagram shows the bearing length, the maximum and minimum factored reaction, and the dead and live load reaction at each support. The badges at the top of the sheet show the bending, shear, bearing, short-term deflection and governing checks.

Summary section listing the factored bending moment, shear and bearing demands with their resistances, the governing deflections and their ratios, each with a utilization badge where it applies, above a Reactions diagram of the beam on two supports.

Look at the graphs

Graphed Load Combination shows the shear, moment and deflection graphs and the vertical load and reactions for the selected load combination, here 1.25D + 1.5L + 1.5Lr. You can choose another combination in the dropdown.

Graphed Load Combination dropdown set to 1.25D + 1.5L + 1.5Lr, with the shear, moment and deflection graphs and the vertical load and reactions graph along the 4 meter beam.

Based on the summary and graphs, a 7x13.5 [175x342] 24f-E Douglas Fir glulam beam passes for this design scenario, with the governing combination 1.25D + 1.5L + 1.5

L_r

(

L_r

is 0 here). The badges show utilization, so the tight checks are shear at 98% and bearing at 84%. Shear governs, and no smaller beam is suggested.

Inputs, Calcs.com output and a hand check

Inputs

Member typeGlulam

Size and grade7x13.5 24f-E D.Fir-L

Number of plies1

Beam plan length

L_X

4000 mm

Continuous bracingNone

SupportsPinned, Roller

Support positions0 mm, 4000 mm

Bearing length75 mm, both

Line load, 0 to 4000 mmD 10 kN/m, L 15 kN/m

Roof live load0

Self-weightIncluded (D 0.287 kN/m)

Bending axisStrong (X-X)

Service conditionDry

TreatedUntreated

System factorNo System Factor

Deflection limits25 mm, L/360, L/240

Calcs.com output

Factored bending moment

M_f

70.7 kN·m

Factored bending moment resistance

M_r

94 kN·m (75%)

Factored shear

V_f

70.7 kN

Factored shear resistance

V_r

71.8 kN (98%)

Factored bearing demand

Q_f

70.7 kN

Factored bearing capacity

Q_r

84.5 kN (84%)

Live / short-term deflection

\delta_{ST}

−6.7 mm (60%)

Deflection limit

\Delta_{ST,max}

11.1 mm

Long-term deflection

\delta_{LT}

−4.59 mm (28%)

Governing badge98%

Reaction, factored maximum70.7 kN

Reaction, factored minimum18.5 kN

Reaction, D20.6 kN

Reaction, L30 kN

Hand check

Dead load with self-weight:

w_D = 10 + 0.287 =

10.287 kN/m, so the dead load reaction is

10.287(4) / 2 =

20.6 kN

Factored line load:

w_f = 1.25(10.287) + 1.5(15) =

35.36 kN/m

M_f = w_f L^2 / 8 = (35.36)(4^2) / 8 =

70.7 kN·m, so

M_f / M_r = 70.7 / 94 = 0.75

V_f = w_f L / 2 = (35.36)(4) / 2 =

70.7 kN, so

V_f / V_r = 70.7 / 71.8 = 0.98

Minimum reaction: 0.9(20.6) = 18.5 kN, from the 0.9D uplift combinations (no wind entered)

This is a sanity check on the demands and the reactions only. It uses the 1.25D + 1.5L + 1.5 $L_r$ combination shown on the graphs, with $L_r$ = 0 and L = 4 m, and the dead load from the sheet’s own load diagram. Calculator version 33, Generic Beam preset.

Access the full PDF file here: [CA] Wood Beam Example

Method & scope

Property	Detail
Design standards	CSA O86:19, NBCC 2015, CWC Wood Design Manual 2017
Regions	Canada
Presets	Generic Beam, Floor Joist, Floor Girder, Ceiling Joist, Ridge Beam, Roof Header, Floor Header, Combination Beam
What it checks	Structural model and load combinations, Bending moment resistance (CSA O86:19 Cl.7), Shear resistance (CSA O86:19 Cl.6.5.4.3), Bearing capacity, Deflection checks (CSA O86:19 Cl.5.4.2 / NBCC Commentary D)
Key assumptions	As listed in the calculator’s Sheet Details: 1. Members are straight, prismatic (not-tapered) and not notched. 2. Axial load is assumed to be negligible. 3. Shear is conservatively taken at the absolute highest location, which may be directly over support, instead of distance d as allowed per code. 4. For glulam beams, the CSA O86 simplified shear resistance method is used, valid for members with volume < 2 $m^3$ . 5. There are no significant point loads near supports (special bearing provisions for loads near supports are not considered). 6. Bearing is not considered at point loads. 7. ClearCalcs [Now Calcs.com] doesn’t apply importance factors to load combinations. 8. For built-up beams, all plies are connected adequately and load is spread evenly. 9. The X axis corresponds to the beam major axis. In multi-ply members, this refers to the individual plies’ major axis.

See the exact clause

Every check in this calculator links back to its governing clause in CSA O86. Open the Formula Reference panel on any result and select the clause reference to read it. See Viewing Clauses from Inside a Calculator.

Symbols

These are the symbols used on this page. The names for the sheet’s inputs and results are the labels the calculator shows; the others are as described in the sections below and in the calculator’s explanations.

Symbol	Meaning
$n_{plies}$	Number of Plies
$L_X$	Beam Plan Length
$L$	Total Material Length
$L_b$	Bearing Length
$b$	Width of the section
$d$	Depth of the section
$M_f$	Factored Bending Moment
$M_r$	Factored Bending Moment Resistance
$V_f$	Factored Shear
$V_r$	Factored Shear Resistance
$Q_f$	Factored Bearing Demand
$Q_r$	Factored Bearing Capacity
$\delta_{ST}$	Governing Live / Short-Term Deflection
$\delta_{LT}$	Governing Long-Term Deflection
$\Delta_{ST,max}$	Live / Short-Term Deflection Limit
$\Delta_{max}$	Deflection Limit Absolute Limit
$(L/)_{ST}$ , $(L/)_{LT}$	Live / Short-term and Long Term Deflection Limit ratios
$F_b$	Reference bending strength
$F_v$	Reference shear strength
$K_H$	System factor for repetitive-member assemblies
$K_{Scs}$	Service-condition factor for bending
$K_T$	Treatment factor
$K_{zbg}$	Size factor for sawn lumber, or volume factor for glulam members
$C_B$	Slenderness ratio, $L_e \times d / b^2$ , for each unbraced segment
$L_e$	Effective length, taken as 1.92 times the unbraced length
$K_L$	Lateral stability factor, set by the Continuous Bracing for Lateral Torsional Buckling choice
$w_D$	Dead line load including self-weight, in the worked example hand check
$w_f$	Factored line load, in the worked example hand check
$K_D$	Load-duration factor
$P_x$	Column lateral input that a linked beam reaction is routed to
$N_y$	Column axial input that a linked beam reaction is routed to
$M$	Support moment transferred to a linked column

Calculation method

Structural model and load combinations

The calculator models the beam as a one-dimensional element and computes bending moment, shear, and deflection diagrams under each NBCC 2015 load combination. Loads are entered by type, dead (D), live (L), snow (S), wind (W), and the calculator automatically generates all governing strength (ULS) and serviceability (SLS) combinations, for example:

1.25D + 1.5L
1.25D + 1.5S + 1.0L
0.9D + 1.5W (uplift check)

Three independent sets of serviceability combinations are generated for short-term (live/snow), long-term (sustained dead load), and simplified DL+LL deflection checks.

Bending moment resistance (CSA O86:19 Cl.7)

Factored bending resistance

M_r

is computed from the reference bending strength

F_b

adjusted by a chain of CSA O86:19 factors:

$K_H$ , system factor for repetitive-member assemblies
$K_{Scs}$ , service-condition factor for bending
$K_T$ , treatment factor
$K_{zbg}$ , size factor for sawn lumber, or volume factor for glulam members

Lateral stability is checked by computing the slenderness ratio

C_B = L_e \times d / b^2

for each unbraced segment, with

L_e

taken as 1.92 times the unbraced length for any loading. Where

C_B

exceeds the threshold for full resistance, the lateral stability factor

K_L

is applied. The slenderness ratio must remain at or below 50 per CSA O86:19 Cl.7.5.6.4, the calculator flags a failure if this limit is exceeded. moment utilization

= M_f / M_r \le 1.0

Shear resistance (CSA O86:19 Cl.6.5.4.3)

Factored shear resistance

V_r

applies the service-condition, treatment, and size adjustment factors to the reference shear strength

F_v

. For glulam members the calculator uses the CSA O86 simplified shear strength method, which is valid for members with volume under 2 m³. Shear demand is taken at the location of peak shear, which may conservatively be directly over the support rather than at distance d. shear utilization

= V_f / V_r \le 1.0

Bearing capacity

For each support, factored bearing demand

Q_f

is checked against factored bearing resistance

Q_r

, adjusted for service condition and treatment. A bearing contact area is specified per support; the check is skipped for supports with zero contact area.

Deflection checks (CSA O86:19 Cl.5.4.2 / NBCC Commentary D)

Three independent deflection limits are verified per span:

Live/short-term deflection, governed by short-term serviceability load combinations; checked against a user-defined span/n ratio
Long-term deflection, the elastic deflection under sustained dead load including self-weight; checked against a separate span/n ratio
Simplified DL+LL deflection, total dead-plus-live deflection checked against a third span/n limit

An optional absolute deflection limit in mm can be applied alongside any span-ratio limit. The governing deflection ratio per span is reported against each active limit.

Load linking

Support reactions are exported as linked outputs. When this beam is part of a larger project, connected column and footing calculations downstream automatically receive updated reactions whenever the beam inputs change, no manual re-entry of loads required.

How to use it

Key Properties

Size and GradeIn Calcs.com, you can select the size of the member you want from a list of industry-standard sized members by using the “Select” button. Using the corresponding filters, you can view available options based on the chosen type, species, grade, manufacturer, and nominal size. The Type filter offers Beam & Stringer, Dimension Lumber, Glulam, LVL and Timber. You can also type in the search box at the top of the dialog, or set a maximum width and depth. Each row shows the member’s width, depth, species and grade, with a utilization badge for each check. If the species or grade you need is not listed, use the link at the bottom of the dialog to let us know.

Size and Grade dialog with a search box, filters for type, manufacturer, species, nominal size and grade, maximum width and depth fields, and a list of sections showing width, depth, species, grade and a utilization badge for each check.

Number of PliesThe number of wood plies or boards in the beam. You need to have at least one board in your beam. Plies are boards fastened flat side to flat side, and the bending axis stays specified relative to the individual boards. For example, if 5 plies of 2x6’s are used, the X bending axis remains in the long direction of one board.Beam Plan LengthThe Beam Plan Length is equal to the length of the beam, from start to end, including any intermediate supports. It does not account for slopes, if present. The Total Material Length shown below it is calculated by the sheet and is equal to the Beam Plan Length.Continuous Bracing For Lateral Torsional BucklingYou need to specify whether your beam has no continuous bracing, bracing continuous at the top edge only, bracing continuous at the bottom edge, or both. The bracing conditions determine the lateral-stability factor

K_L

. If the beam is fully braced, lateral torsional buckling calculations are not performed. Continuous bracing at the top edge prevents lateral torsional buckling in positive bending, and bottom edge bracing prevents it in negative bending. For sawn lumber, when you specify continuous bracing, Calcs.com will provide you with a short description of the CSA O86 requirements for bracing based on the width to depth ratio.

Continuous Bracing for Lateral Torsional Buckling dropdown open with the options No continuous bracing, Top edge, Bottom edge and Top & bottom edge.

Supports and BracesThis section is where you can select the support type or bracing type from a drop-down menu and then specify the location of each support/brace in millimeters (mm) or feet (ft) as measured from the leftmost position of the beam. The first support does not have to be at 0, and the last support does not have to be at the length of the beam, for example in a double cantilever. Additionally, for each support, you must specify a bearing length in millimeters (mm) or inches (in) for a simple bearing check. To ignore bearing checks, simply enter a bearing length of 0.

Support/Brace Type dropdown open in the Supports and Braces table, listing Fixed, Pinned, Roller, Hinge, Top Brace and Bottom Brace.

Loads

Load DiagramThe load diagram provides a live illustration of the beam and the assigned loading.LoadsLoads can be input as distributed, line, point, and moment loads in this section using the corresponding tables. You need to specify the location of the load in millimeters (mm) or inches (in) from the leftmost position and the respective load magnitude. To input load magnitude, select the load magnitude box or click the “Edit” text. For each corresponding load, a load magnitude table will appear where you will specify the type of load (Dead, Live, etc) and the respective magnitude in metric or imperial units.Enter the loads unfactored. The load combinations are then generated automatically in accordance with NBCC 2015, or as set in the custom defaults. Calcs.com does not automatically apply load importance factors to the entered loads, so apply them manually when entering the value (or using a custom formula) in the relevant input fields for snow, wind and earthquake loads. Uplift wind forces (Wu,up) should be positive.Load Magnitude table for Distributed Loads (kiloPascals (kPa) or pounds per square foot (psf))

Load Magnitudes dialog for a distributed load, with a load type and a magnitude per area in kPa on each row.

Load Magnitude table for Line Loads (kiloNewtons per meter (kN/m) or pounds per linear foot (plf))

Load Magnitudes dialog for a line load, with a load type and start and end magnitudes in kN/m on each row.

Load Magnitude table for Point/Moment Loads (kiloNewtons (kN) or pounds (lb) and kiloNewton-meter (kN*m) or pound-feet (lb*ft))

Load Magnitudes dialog for a point or moment load, with a load type, a vertical load in kN and a moment load in kN·m on each row.

Bending AxisCalcs.com requires you to specify if the beam is being loaded on the strong or weak axis. Calcs.com sets the default to the strong axis / joist (X-X). The strong axis corresponds to joist orientation and the weak axis to plank orientation. In multi-ply members, the X axis refers to the individual plies’ major axis.

Illustration of a strong axis beam, loaded on its deep side, next to a weak axis beam, loaded on its wide side.

Self-WeightCalcs.com allows you to choose to include or exclude the self-weight of the beam in your calculations. The calculator is set to include the self-weight by default unless you specify otherwise. This can play a difference if you’re comparing against a published span table, where the self-weight of joists is often included in the superimposed dead load.Load Direction When Linking to ColumnThis controls how reactions are formatted when linking this member to a supporting column. Axial (Ny) is the default. Use it for standard gravity and combined loading. It transfers the full reaction to the column, decomposed by load type: the horizontal component to

P_x

, the vertical component to

N_y

, and the support moment to M. For inclined rafters, both the vertical reaction and the horizontal thrust are included in one link. Lateral (Px) is for a separate wind or lateral load path only. It routes reactions to the column lateral input (

P_x

) with no axial component (

N_y

) from this link. The support moment (M) still transfers.

Design Conditions

Design Code for Load Combinations: Shows the design code used for the load combinations, the National Building Code of Canada (2015). It may be changed in the Project Defaults sheet for the project, and it cannot be changed in an individual calculation.
Design Standard Edition Note: A note that the calculation is based on the 2019 edition of the CSA O86 wood design standard, while the NBCC 2015 specifies the 2014 edition.
Service Condition: You need to indicate if the service condition is ‘dry’ or ‘wet.’ It is considered dry if the average equilibrium moisture content of the wood is 15% or less on average over a year without exceeding 19%. Wet service conditions are all other service conditions, and most often apply only to exterior use. Structural composite lumber (LVL, PSL, etc.) and I-joist products are usually not to be used in wet conditions. The service-condition factor appears in the Modulus of Elasticity, Bending Moment Resistance, Shear Resistance and Bearing sections as an adjustment factor.
Treatment: Calcs.com requires you to indicate if the wood beam is untreated, or if it is preservative-treated and whether it is incised (partially cut) or unincised. The options are Untreated, Preservative-treated non-incised and Preservative-treated incised. The treatment factor depends on the incising and treatment of the lumber, and appears as an adjustment factor in the Modulus of Elasticity, Bending Moment Resistance, Shear Resistance and Bearing sections.
System Factor: A system factor is considered if the member is part of a system where loads can be shared. There are three options for sawn lumber:
- No System Factor: There are less than 3 beams spaced 610 mm apart and/or are not mutually sharing loads
- Case 1 (for systems that don’t meet Case 2 requirements): There are more than 3 beams spaced less than 610 mm apart, mutually sharing loads
- Case 2 (typical for joists and rafters): All of the following conditions are met
  - There are more than 3 beams spaced less than 610 mm apart, mutually sharing the load
  - Members are sheathed with a minimum of 9.5 mm OSB, waferboard, plywood or with min. 17mm lumber with panel coverings.
  - The sheathing is attached with sufficient stiffness and adequate spacing equal to 2 common nails at 150 mm on center at edges and 300 mm on center elsewhere.
- For glulam and SCL (LVL) products, there is no Case 1 or Case 2. The only condition is that the members are used in a load-sharing system of at least three parallel members with a maximum of 610 mm center-to-center spacing.
Storage Live Load: A storage live load is a live load (loads due to occupancy use) that occurs for a long duration. An example of this is storage in an attic. If this is set to yes, the duration factor associated with live load will be taken the same as dead load, and the load factor on live load will be increased in some combinations. A long duration live load has a decreased load-duration factor of 0.65 ( $K_D$ ) for load combinations of dead load plus live load only.
Consider Shear Deflection: Shear deflection can be a significant component of total deflection due to the low shear modulus. In particular, specifications for structural composites such as LVL often require that shear deflection be directly accounted for. If this is set to “Yes”, we use an approximation based on the peak moment within a span to find the shear deflection. This gives exact results for simply supported and cantilever spans with either a point load in the center or a UDL.
Absolute Deflection Limit: The maximum allowable deflection for the beam in millimeters (mm) or inches (in), regardless of span length. Normally, your local building code will dictate this.
Live/Short-term Deflection Ratio: The maximum allowable deflection ratio for live and short loading, calculated independently for each span. The default is L/360 but you may change this to a preferred ratio.
Long Term Deflection Ratio: The maximum allowable deflection ratio for long-term loading, calculated independently for each span. The default is L/240 but you may change this to a preferred ratio.
Double Length/Allowable Deflection for Cantilevers: For cantilever spans, it’s typical to take “L” as double the span length. To adjust for this, the allowable deflection can be doubled.

Summary and Graphs

In the summary section, the key parameters of your calculation will be outlined. In the graphs section, you can select the load combination you would like to see in the graphs. Along the top of the sheet, a row of badges shows the utilization for Bending, Shear, Bearing, ST Deflect and Governing.

Summary section listing the factored bending moment, shear and bearing results, the governing deflections and their ratios, each with a utilization badge where it applies, and a reactions diagram.

Shear, moment and deflection diagrams and the vertical load and reactions diagram along the beam, for the 1.25D + 1.5L + 1.5Lr load combination.

Choose the load combination for the graphs from the Graphed Load Combination dropdown.

Graphed Load Combination dropdown open, listing the load combinations from 1.4D to 0.9D + 1.5L + 1.0Su.

Additionally, in the associated tabs, below design conditions, you can see the respective parameters used to derive the summary figures and calculations. These include the following.

Load Combination Analysis
Unfactored Load Analysis
Modulus of Elasticity (CSA O86:19 Section 6.3)
Bending Moment Resistance (CSA O86:19 Section 6.5.3)
Positive Bending (CSA O86:19 Section 6.5.3)
Negative Bending (CSA O86:19 Section 6.5.3)
Shear Resistance (CSA O86:19 Section 6.5.4)
Bearing (Compressive Resistance Perpendicular to Grain) (CSA O86:19 Section 6.5.6)
Deflections

In the Positive Bending and Negative Bending tabs, the table Effective Length Calculation - Unbraced Length shows the effective length, which is always 1.92 times the unbraced length for any loading. This table only shows when lateral-torsional buckling is checked.These parameters were calculated based on the input loads and key properties.

Available presets

Each preset opens the calculator with a typical setup already entered.

Preset	Open in Calcs.com
Generic Beam	Run with preset
Floor Joist	Run with preset
Floor Girder	Run with preset
Ceiling Joist	Run with preset
Ridge Beam	Run with preset
Roof Header	Run with preset
Floor Header	Run with preset
Combination Beam	Run with preset

Common questions

What design standard does this calculator use?

The calculator designs wood beams to CSA O86:19 (Limit States Design) with load combinations per NBCC 2015. Species and grade properties are drawn from the CWC Wood Design Manual 2017. Supported product types include sawn lumber (the Beam & Stringer, Dimension Lumber and Timber size classes), glulam, and LVL.

What are the key inputs?

Key inputs include the wood section (species, grade, and product type from the built-in database), beam plan length, number of plies, service condition (dry or wet), treatment, support layout, loads by type (dead, live, snow, wind), lateral top-flange bracing spacing, and three independent deflection limit ratios.

What checks and outputs does it produce?

The calculator checks factored bending moment resistance (

M_f / M_r \le 1.0

), shear resistance (

V_f / V_r \le 1.0

), bearing capacity at each support, governing live/short-term deflection, long-term deflection, and simplified DL+LL deflection, each against user-defined span ratios and an optional absolute limit. Lateral stability (slenderness ratio ≤ 50) is verified per CSA O86:19 Cl.7.5.6.4.

Can it handle multi-ply beams and glulam?

Yes. Multi-ply (built-up) beams are supported in strong-axis bending with any number of plies. Glulam checks use the CSA O86 simplified shear resistance method, valid for members with volume under 2 m³, the calculator enforces this limit automatically. LVL products from West Fraser, Versa-Lam and Microllam are included in the section database. Weak-axis bending is supported for single-ply members only.

How do I select a wood section?

Use the section picker to filter by product type (Beam & Stringer, Dimension Lumber, Timber, Glulam, LVL), species group, and grade. The calculator loads CSA O86:19 tabulated reference design values automatically. You can also define a custom section by entering cross-section dimensions and manually entering design values if your species or grade is not in the built-in database.

Does this calculator support load linking with column and footing calculations?

Yes, beam reactions link directly to connected column and footing calculations in the same project. When you change a span, load, or section, all downstream calculations update automatically, no manual re-entry of reactions required.

Next steps

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How the lateral stability factor KL for wood beams in bending is calculated to CSA O86:19, including effective lengths for common loading conditions.

Design a Sloped or Angled Member

Design rafters, hip beams and other inclined members: set the slope, choose plan or inclined view, pick a load orientation, or convert lengths with formulas.

​Worked example

​Example 1: simply supported beam

​Method & scope

​See the exact clause

​Symbols

​Calculation method

​Structural model and load combinations

​Bending moment resistance (CSA O86:19 Cl.7)

​Shear resistance (CSA O86:19 Cl.6.5.4.3)

​Bearing capacity

​Deflection checks (CSA O86:19 Cl.5.4.2 / NBCC Commentary D)

​Load linking

​How to use it

​Available presets

​Common questions

​Next steps

Design a Wood Column to CSA O86

🇨🇦 Calculators for Canada

Generalized Lateral Stability Calculation for Wood Beams

Design a Sloped or Angled Member

Worked example

Example 1: simply supported beam

Method & scope

See the exact clause

Symbols

Calculation method

Structural model and load combinations

Bending moment resistance (CSA O86:19 Cl.7)

Shear resistance (CSA O86:19 Cl.6.5.4.3)

Bearing capacity

Deflection checks (CSA O86:19 Cl.5.4.2 / NBCC Commentary D)

Load linking

How to use it

Available presets

Common questions

Next steps