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Exterior Timber Louver Solar Shading Angle Calculator

Calculate the louver spacing needed to achieve a target solar cutoff (shading) angle.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Required louver spacing

0.49 ft

Check your inputs

This gives full shading only for sun angles above the cutoff angle you enter — determine your target cutoff angle from your latitude and the season/time you want to block direct sun (e.g. using a solar path chart for your location).

For the dimensions entered, expect a required louver spacing of 0.15 m. Moderate confidence — sound arithmetic, but allow for the variation any real site introduces. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • For fixed horizontal louvers, the required spacing to block sun above a target cutoff angle is: spacing = louver depth ÷ tan(cutoff angle), standard solar shading geometry

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Frequently asked questions

Why does a higher cutoff angle require closer louver spacing?
As the target cutoff angle increases, tan(cutoff angle) grows, so spacing = louver depth ÷ tan(cutoff angle) shrinks — closer spacing is needed to keep blocking sun that's coming in at a steeper angle relative to the wall.
How do I choose the right cutoff angle?
The target cutoff angle should be based on your latitude and the specific season and time of day you want to block direct sun — a solar path chart for your location will show the sun angles you're designing against.
Does this account for sun angles below the cutoff angle?
No — this spacing only guarantees blocking for sun above the cutoff angle you enter. Lower sun angles (e.g. early morning, late afternoon, or winter sun) can still pass between the louvers depending on their direction relative to the wall.