Ridge beam calculator
Set the span, rafter spacing and roof loads (dead + live + snow). The calculator converts rafter reactions to point loads on the ridge and reports reactions, maximum moment, deflection and stress.
About this case
How to use this ridge beam calculator
Model the ridge as simply supported (if bearing on walls at both ends) or overhanging (if it projects past a gable end). Enter the rafter spacing, roof span, and the total design load (dead + live + snow) in psf or kPa. The calculator converts this to point loads at each rafter position: load per rafter = area_load × spacing × span / 2.
Pick a timber section (rectangular) or enter a custom I and area. The material preset is timber at E = 11 GPa; upgrade to glulam/LVL by entering the manufacturer's modulus. Self-weight adds the ridge's own weight as a small UDL automatically.
Reading the results for a ridge beam design
The dashboard shows the maximum moment (typically at midspan for a simply supported ridge, or over the interior support for an overhanging ridge) and maximum deflection. Compare bending stress against F_b from the NDS or the product's design values. Check deflection against L/240 for roofs; L/360 if the ridge supports a finished ceiling below.
If the ridge is continuous over three or more supports, switch to the continuous two-span calculator and add more supports as needed — the negative moment over the middle support is typically the design driver.
Common ridge beam mistakes this tool helps you catch
Applying the total roof load as a UDL instead of point loads at rafter spacing overestimates the moment (a UDL on a simply supported beam gives wL²/8, but discrete point loads produce lower midspan moment for the same total load). Forgetting snow drift or unbalanced load cases when the ridge spans different roof areas. And using a simply supported model when the ridge is actually continuous over interior posts.