Structural Load-Bearing Wall Identification Risk Calculator

ANA›Life Services Authority›National Calculator Authority›Structural Load-Bearing Wall Identification Risk Calculator

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Structural Load-Bearing Wall Identification Risk Calculator

Estimates the composite risk score for misidentifying a structural load-bearing wall based on building characteristics, wall properties, and available documentation. Uses a weighted risk index model aligned with structural engineering assessment frameworks.

Building Age (years)

Number of Stories Above Wall

Wall Thickness (inches)

Wall Length (feet)

Floor/Roof Joists Run Perpendicular to Wall?

-- Select -- Yes No Unknown

Wall Position in Structure

-- Select -- Exterior Wall Center/Interior Spine Wall Other Interior Wall Basement/Foundation Wall

Construction Type

-- Select -- Masonry / Brick / CMU Wood Frame (Platform/Balloon) Steel Frame Reinforced Concrete Unknown

Original Blueprints / Structural Drawings Available?

-- Select -- Yes – Full Structural Drawings Partial / Architectural Only No Drawings Available

Structural Engineer Review Conducted?

-- Select -- Yes No

Prior Undocumented Renovations Known or Suspected?

-- Select -- Yes No Unknown

Calculate Risk ...

function slbw_calc() { var resultDiv = document.getElementById('slbw_result');

// --- Collect Inputs --- var age = parseFloat(document.getElementById('slbw_building_age').value); var stories = parseFloat(document.getElementById('slbw_stories').value); var thickness = parseFloat(document.getElementById('slbw_wall_thickness').value); var length = parseFloat(document.getElementById('slbw_wall_length').value); var perpJoists = document.getElementById('slbw_perpendicular_joists').value; var position = document.getElementById('slbw_wall_position').value; var constrType = document.getElementById('slbw_construction_type').value; var blueprints = document.getElementById('slbw_blueprints').value; var engReview = document.getElementById('slbw_engineer_review').value; var renovHist = document.getElementById('slbw_renovation_history').value;

// --- Validation --- var errors = []; if (isNaN(age) || age 500) errors.push("Building age must be between 0 and 500 years."); if (isNaN(stories) || stories 20) errors.push("Stories above wall must be between 0 and 20."); if (isNaN(thickness) || thickness 36) errors.push("Wall thickness must be between 1 and 36 inches."); if (isNaN(length) || length 200) errors.push("Wall length must be between 1 and 200 feet."); if (perpJoists === "") errors.push("Please select joist orientation."); if (position === "") errors.push("Please select wall position."); if (constrType === "") errors.push("Please select construction type."); if (blueprints === "") errors.push("Please select blueprint availability."); if (engReview === "") errors.push("Please select whether an engineer review was conducted."); if (renovHist === "") errors.push("Please select renovation history status.");

if (errors.length > 0) { resultDiv.innerHTML = 'Input Errors:' + errors.map(function(e){ return ''; }).join('') + ''; return; }

// ============================================================ // RISK INDEX MODEL // Composite Risk Score (CRS) = sum of weighted sub-scores // Each factor scored 0–10, multiplied by its weight. // Total possible weighted score = sum of all weights × 10 // Final Risk % = (CRS / MaxCRS) × 100 // ============================================================

// --- Factor 1: Structural Load Indicator (SLI) --- // Based on stories above wall and wall position // Score 0–10 var positionScore = 0; if (position === "basement") positionScore = 10; else if (position === "exterior") positionScore = 8; else if (position === "center") positionScore = 9; else if (position === "interior_other") positionScore = 4;

var storiesScore = Math.min(stories * 2.0, 10); // 0 stories=0, 5+ stories=10

var SLI = (positionScore * 0.6) + (storiesScore * 0.4); // weighted blend, 0–10 var W_SLI = 0.25;

// --- Factor 2: Physical Wall Characteristics Score (PWC) --- // Thickness: thicker walls more likely load-bearing // Masonry: 8+ in typical; wood frame: 3.5–5.5 in typical var thicknessScore = 0; if (thickness >= 12) thicknessScore = 10; else if (thickness >= 8) thicknessScore = 8; else if (thickness >= 6) thicknessScore = 6; else if (thickness >= 4) thicknessScore = 4; else thicknessScore = 2;

// Length: longer walls span more area, higher structural role var lengthScore = Math.min((length / 20) * 10, 10); // 20 ft = score 10

var PWC = (thicknessScore * 0.5) + (lengthScore * 0.5); var W_PWC = 0.15;

// --- Factor 3: Joist Orientation Risk (JOR) --- // Perpendicular joists = strong indicator of load-bearing var jorScore = 0; if (perpJoists === "1") jorScore = 9; // perpendicular = high load-bearing likelihood else if (perpJoists === "0.5") jorScore = 5; // unknown = moderate risk else jorScore = 2; // parallel = less likely load-bearing var W_JOR = 0.15;

// --- Factor 4: Construction Type Ambiguity Score (CTA) --- // Some construction types are harder to assess without drawings var ctaScore = 0; if (constrType === "unknown") ctaScore = 10; else if (constrType === "masonry") ctaScore = 7; // masonry walls often all load-bearing else if (constrType === "wood_frame") ctaScore = 6; // mixed load/non-load bearing else if (constrType === "concrete") ctaScore = 5; // usually clearly structural else if (constrType === "steel_frame") ctaScore = 4; // columns carry load, walls less so var W_CTA = 0.10;

// --- Factor 5: Documentation Deficiency Score (DDS) --- var ddsScore = 0; if (blueprints === "none") ddsScore = 10; else if (blueprints === "partial") ddsScore = 5; else ddsScore = 1; // full drawings = low documentation risk var W_DDS = 0.15;

// --- Factor 6: Engineering Oversight Score (EOS) --- // No engineer review = high risk of misidentification var eosScore = (engReview === "no") ? 10 : 0; var W_EOS = 0.12;

// --- Factor 7: Building Age & Renovation Uncertainty (BARU) --- // Older buildings + undocumented renovations = higher uncertainty var ageScore = 0; if (age >= 100) ageScore = 10; else if (age >= 60) ageScore = 7; else if (age >= 30) ageScore = 4; else ageScore = 2;

var renovScore = 0; if (renovHist === "yes") renovScore = 10; else if (renovHist === "unknown") renovScore = 6; else renovScore = 0;

var BARU = (ageScore * 0.5) + (renovScore * 0.5); var W_BARU = 0.08;

// --- Composite Risk Score --- // CRS = Σ (factor_score × weight) // Max CRS = 10 × Σ weights = 10 × 1.00 = 10 var CRS = (SLI * W_SLI) + (PWC * W_PWC) + (jorScore * W_JOR) + (ctaScore * W_CTA) + (ddsScore * W_DDS) + (eosScore * W_EOS) + (BARU * W_BARU);

var maxCRS = 10 * (W_SLI + W_PWC + W_JOR + W_CTA + W_DDS + W_EOS + W_BARU); // maxCRS = 10 × 1.00 = 10

var riskPercent = (CRS / maxCRS) * 100;

// --- Risk Category --- var riskCategory = ""; var riskColor = ""; var recommendation = "";

if (riskPercent ' + riskPercent.toFixed(1) + '%

' + '' + '#### Factor Breakdown ' + '' + 'FactorScore (0–10)WeightContribution' + 'Structural Load Indicator (SLI)' + SLI.toFixed(2) + '' + W_SLI + '' + (SLIW_SLI).toFixed(3) + '' + 'Physical Wall Characteristics (PWC)' + PWC.toFixed(2) + '' + W_PWC + '' + (PWCW_PWC).toFixed(3) + '' + 'Joist Orientation Risk (JOR)' + jorScore.toFixed(2) + '' + W_JOR + '' + (jorScoreW_JOR).toFixed(3) + '' + 'Construction Type Ambiguity (CTA)' + ctaScore.toFixed(2) + '' + W_CTA + '' + (ctaScoreW_CTA).toFixed(3) + '' + 'Documentation Deficiency (DDS)' + ddsScore.toFixed(2) + '' + W_DDS + '' + (ddsScoreW_DDS).toFixed(3) + '' + 'Engineering Oversight (EOS)' + eosScore.toFixed(2) + '' + W_EOS + '' + (eosScoreW_EOS).toFixed(3) + '' + 'Building Age & Renovation Uncertainty (BARU)' + BARU.toFixed(2) + '' + W_BARU + '' + (BARUW_BARU).toFixed(3) + '' + '' + '' + 'Recommendation:* ' + recommendation + '

'; }

#### Formula

Composite Risk Score (CRS):

CRS = (SLI × 0.25) + (PWC × 0.15) + (JOR × 0.15) + (CTA × 0.10) + (DDS × 0.15) + (EOS × 0.12) + (BARU × 0.08)

Risk Percentage:

Risk % = (CRS / 10) × 100

Sub-factor formulas:

Risk Categories: Low (<25%) | Moderate (25–49%) | High (50–74%) | Critical (≥75%)

#### Assumptions & References

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