LVL Rafter Calculator
Builders Supply · Project Calculators
LVL Rafter Calculator
For sloped rafters that span farther than sawn lumber — lean-tos, porch roofs, and single-slope roofs framed with rafters instead of trusses. Give us the span, spacing, pitch, and load; we'll size the Versa-Lam® LVL and tell you the length to order.
Final sizes must be confirmed by a licensed engineer before you build or pull a permit. Builders Supply can get your design stamped and supply the material — just ask.
Sizing based on Boise Cascade® published Versa-Lam® LVL 2.1E-3100 load tables. Builders Supply is a stocking dealer.
Your lean-to roof
A single slope off the main building. Each rafter spans from the building wall down to the outer wall or beam.
Shop the job
Rafters plus what it takes to set the roof. Tap to add to your list.
Need it engineered or stamped?
Rafters that cantilever past the wall for an overhang, run over a mid-support, or carry point loads — plus any permit job — Builders Supply will get it sealed by a licensed engineer and supply the LVL.
Sizes come from Boise Cascade's published Versa-Lam® LVL 2.1E-3100 beam load tables (Product Data MTP-E7000), applied to a single simple-span rafter carrying a tributary strip equal to its spacing: load per rafter (PLF) = roof load (psf) × spacing (ft), looked up at the horizontal span. Roof load is taken on the horizontal (plan) projection per code; pitch is used only to report the sloped length to order. Assumes a simple span (one clear span, no cantilever/overhang or mid-support), uniform load, dry use, and lateral support of the compression edge. Excludes wind uplift, point loads, and drifting/unbalanced snow. Built-up widths: 1¾″ = 1-ply, 3½″ = 2-ply, 5¼″ = 3-ply. 1.8E-2650 grade added when its load tables are sourced. Material-selection guide — confirm against your building code, or with a licensed engineer for permitted work.