Sources & References
Every IRC code section, span table, and cost figure in DeckMath traces back to a primary source — building codes, wood-engineering standards, government economic data, or peer-reviewed research. This page lists all of them by name, publisher, year, and the specific values we derive from each. No second-hand citations.
Building codes
Every dimension, span, and structural requirement in DeckMath maps to a specific IRC 2021 section.
Used for · Frost-depth bearing requirements (R403.1.4); pier and post-foundation construction (R403.1.4.1); footing dimensions (Table R403.1).
Open primary sourceUsed for · Joist span tables (R502.3.1) for 2×6 through 2×12 lumber in SPF, southern pine, and Douglas fir at 12/16/24 inch on-center; L/360 deflection limit (R502.3.2).
Open primary sourceUsed for · Stair geometry: max riser height 7-3/4″ (R311.7.5.1), min tread depth 10″ (R311.7.5.2), min stair width 36″ (R311.7.1), handrail requirements (R311.7.8).
Open primary sourceUsed for · Guard height 36″ residential (R312.1.2); 4-inch sphere baluster spacing rule (R312.1.3); guard openings at stairs (R312.1.3 exception).
Open primary sourceUsed for · Prescriptive deck construction (R507.1-R507.13); ledger attachment (R507.9); deck guardrail post-to-deck connection (R507.9.1.3); footing types (R507.3).
Open primary sourceMaterial engineering
Wood values, fastener specs, and preservative ratings come from the canonical engineering references.
Used for · Allowable bending and shear stresses for lumber species + grade combinations; deflection calculations under live load (Section 3.5); load duration factor adjustments.
Open primary sourceUsed for · Prescriptive joist span tables; beam sizing for residential floor and deck framing; deck-specific connector requirements.
Open primary sourceUsed for · Wood species properties (modulus of elasticity, fiber stress); decay resistance ratings; treatment retention values for pressure-treated lumber.
Open primary sourceUsed for · Pressure-treatment retention requirements by use category (UC3B ground contact, UC4A ground-and-fresh-water); chemical preservative ID codes.
Open primary sourceUsed for · Galvanized fastener corrosion-resistance classes; minimum zinc coating thickness for residential deck fasteners (Class D minimum).
Open primary sourcePricing + labor data
Cost ranges are anchored to public economic data, refreshed quarterly.
Used for · Quarterly lumber price index used to adjust national $/sqft tier baselines. Updated each quarter.
Open primary sourceUsed for · State-level mean hourly wage for residential carpenters; used as the basis for our regional labor multiplier.
Open primary sourceUsed for · Regional cost-of-living differentials applied to material + permit + disposal cost ranges.
Open primary sourceUsed for · Joist-spacing requirements per Trex product line (Transcend, Enhance, Signature); fastener spacing for hidden clip systems; warranty terms.
Open primary sourceUsed for · AZEK PVC vs TimberTech composite spec differences; fastener types and torque; multi-color installation patterns.
Open primary sourceAcademic + government research
Soil bearing, climate, and material movement values pulled from peer-reviewed government sources.
Used for · Presumptive soil bearing values by soil type (clay 1,500 psf, sand 2,000 psf, gravel 3,000 psf); footing-load calculation methodology.
Open primary sourceUsed for · Reference frost-depth values by state used in our climate-zone classification (warm 12″, mid 24″, cold 36″, extreme 48″).
Open primary sourceUsed for · Equilibrium moisture content (EMC) by climate region; wood shrinkage and movement calculations applied to deck-board gap recommendations.
Open primary sourceHow DeckMath uses these sources
See the methodology page for how IRC sections become validation rules, how BLS data becomes our regional labor multiplier, and how we keep these numbers current quarter-over-quarter.
Editorial standards
We do not cite Wikipedia, contractor blogs, or social-media posts as primary sources. If a figure cannot be traced to one of the references above, it is labeled as “estimate” or “industry consensus” and not used in code-compliance checks. Every quarterly refresh of pricing data re-runs against the BLS PPI and the EOS state wage tables — if a delta exceeds ±8%, all affected pages get a new lastmod date in the sitemap.
Spot a citation error? Email [email protected] with the page URL and source — we acknowledge corrections within 5 business days.