# Building Envelope Mastery: The Definitive Detail Reference

> Comprehensive guide to drawing architect-quality building envelope construction details.
> Every transition, every flashing, every sealant joint, every potential failure point.

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## Table of Contents

1. [Water Management Fundamentals](#1-water-management-fundamentals)
2. [Air Barrier Continuity](#2-air-barrier-continuity)
3. [Thermal Bridge Management](#3-thermal-bridge-management)
4. [Sealant Joint Design](#4-sealant-joint-design)
5. [Window & Door Openings](#5-window--door-openings)
6. [Roof-to-Wall Transitions](#6-roof-to-wall-transitions)
7. [Foundation-to-Wall Transitions](#7-foundation-to-wall-transitions)
8. [Through-Wall Flashing & Masonry Veneer](#8-through-wall-flashing--masonry-veneer)
9. [Florida / Hurricane / HVHZ Specific](#9-florida--hurricane--hvhz-specific)
10. [Common Failure Points & Defect Analysis](#10-common-failure-points--defect-analysis)
11. [IECC Insulation Requirements by Climate Zone](#11-iecc-insulation-requirements-by-climate-zone)

---

## 1. Water Management Fundamentals

### The 4 D's of Moisture Management

Every building envelope detail must address all four principles simultaneously:

#### 1.1 Deflection
- **Purpose:** Intercept water at the exterior and redirect it away from critical junctions.
- **Key strategies:**
  - Extended eaves and overhangs (even a 2" overhang significantly reduces wall wetting)
  - Drip edges at all horizontal projections
  - Purpose-designed flashings at every material transition
  - Sloped surfaces: minimum 1/4" per foot away from building on all horizontal surfaces
  - Kick-out flashings at roof-wall intersections to divert water into gutters

#### 1.2 Drainage
- **Purpose:** Provide a path for water that penetrates the cladding to drain out by gravity.
- **Key strategies:**
  - Drainage plane (WRB) behind all cladding systems
  - Rainscreen cavity: minimum 3/8" air gap (3/4" to 1" for masonry veneer)
  - Weep holes at base of all wall assemblies
  - Shingled lapping: upper layer ALWAYS laps over lower layer
  - Gravity is the primary driver; all drainage paths must slope downward and outward

#### 1.3 Drying
- **Purpose:** Allow wall assemblies to dry after wetting events.
- **Key strategies:**
  - Ventilated rainscreen: opening at top and bottom of wall to create convective current
  - Vapor-permeable WRB materials (>10 perms) for outward drying
  - Do NOT trap moisture between two vapor barriers
  - Design so it is easier for water to get out than to get in

#### 1.4 Durability
- **Purpose:** Select materials that withstand periodic wetting without deterioration.
- **Key strategies:**
  - Use rot-resistant or pressure-treated lumber at all exterior contact points
  - Galvanized or stainless steel fasteners and flashings in corrosive environments
  - UV-resistant membranes where exposed
  - Design service life of envelope components to match or exceed building service life

### How Water Gets Into Buildings: The 4 Forces

Understanding these mechanisms is essential for detailing every junction:

| Force | Mechanism | Counter-Strategy |
|-------|-----------|-----------------|
| **Gravity** | Water drips through gaps, follows surfaces downward | Slope surfaces away, shingled lapping, drip edges |
| **Wind Pressure** | Rain driven horizontally into gaps and joints | Pressure-equalized rainscreen, baffled joints, sealants |
| **Capillary Action** | Water wicks through small gaps (<1/4") between materials | Capillary break (air gap >3/8"), drip kerf, drainage cavity |
| **Air Pressure Differential** | Negative pressure inside pulls water through openings | Continuous air barrier, pressure equalization in rainscreen cavity |

### The Shingling Principle (Universal Rule)

**Every layer in the building envelope must lap so that the upper element overlaps the lower element.** This applies to:
- WRB/housewrap sheets (minimum 6" horizontal lap, 4" vertical lap)
- Flashings over flashings
- Head flashing over jamb flashing, jamb over sill
- WRB over head flashing
- Counterflashing over base flashing
- Through-wall flashing: WRB laps over top edge minimum 4"

**Violation of shingling is the single most common cause of water intrusion in construction details.**

---

## 2. Air Barrier Continuity

### Why It Matters
- Uncontrolled air leakage accounts for 25-40% of heating/cooling energy loss
- Air leakage transports moisture into wall cavities (can deposit 100x more moisture than vapor diffusion)
- Creates comfort problems: drafts, cold spots, noise transmission
- Enables fire/smoke spread between compartments

### Air Barrier Performance Requirements (ASTM, measured at 75 Pa)

| Level | Maximum Air Permeance | Test Standard |
|-------|----------------------|---------------|
| **Material** | 0.02 L/(s-m^2) | ASTM E 2178 |
| **Assembly** | 0.20 L/(s-m^2) | ASTM E 283 |
| **Whole Enclosure** | 2.00 L/(s-m^2) | ASTM E 779 |

### Air Barrier Material Options

| Material | Location | Vapor Permeance | Notes |
|----------|----------|-----------------|-------|
| Self-adhered modified bituminous membrane | Exterior | <1 perm (vapor retarder) | Excellent continuity, self-sealing at fasteners |
| Fluid-applied membrane (e.g., Prosoco R-Guard) | Exterior | Variable (1-15 perms) | Bridges irregular substrates, seamless |
| Mechanically-fastened housewrap | Exterior | >10 perms | Requires meticulous taping at all seams |
| Spray polyurethane foam (SPF) | Cavity/Exterior | <1 perm (closed-cell) / >10 (open-cell) | Air + vapor + insulation in one |
| Sealed gypsum board (taped + mudded) | Interior | >10 perms | Common in commercial; fire rated |
| Sheet polyethylene (6-mil) | Interior | <0.1 perm | Cold climates only (CZ 6+); vapor barrier + air barrier |

### Critical Transition Points (Must Be Detailed)

Every detail drawing must show the air barrier as a **continuous bold line** (or hatched material) with no gaps at these locations:

#### Wall-to-Roof
- Air barrier from wall connects to air barrier at roof deck or ceiling
- At truss heels: seal between top plate and roof sheathing
- At balloon-framed walls: blocking + sealant at every floor line
- At cathedral ceilings: air barrier follows roof deck line continuously

#### Wall-to-Foundation
- Exterior membrane terminates into sill seal gasket on foundation wall
- Interior drywall sealed to bottom plate with sealant or gasket
- Rim joist: most critical leak point; seal all 6 sides of rim joist cavity
- Sill plate to concrete: foam sill seal gasket + sealant bead

#### Wall-to-Window/Door
- Rough opening must be wrapped with air barrier membrane continuous with wall air barrier
- Window frame primary seal bonds directly to air barrier material
- Metal flashing at sill must be PART OF the air barrier, not interrupting it
- Use flexible membrane at corners to prevent pinholes and tears

#### Penetrations
- Every pipe, duct, wire, and conduit through the air barrier must be sealed
- Use split-ring gaskets or caulk for small penetrations
- Pre-formed boots for larger penetrations
- Exhaust ducts: seal at penetration, NOT at terminus

### Common Air Barrier Failures

1. **Missing air barrier at rim joist** — Most common failure in platform framing
2. **Discontinuous at dropped ceilings/soffits** — Interior drywall does not follow ceiling line
3. **Unsealed partition wall intersections** — Interior walls create chimney effect to attic
4. **Electrical boxes/recessed lights** — Punched through air barrier without sealing
5. **HVAC ducts in unconditioned space** — Duct leakage = air barrier leakage
6. **Trades coordination failure** — Electrician/plumber punches holes after air barrier installed

---

## 3. Thermal Bridge Management

### What Is a Thermal Bridge?
A direct path of high-conductivity material through the insulated envelope. Wood studs at 16" o.c. represent ~25% of wall area with dramatically reduced R-value. Steel studs are far worse, reducing effective cavity insulation R-value by over 40%.

### Where Thermal Bridges Occur

| Location | Severity | Solution |
|----------|----------|----------|
| Wood studs (16" o.c.) | Moderate (~25% of wall is uninsulated) | CI over exterior sheathing |
| Steel studs | Severe (>40% R-value loss) | CI is mandatory; minimum R-7.5 exterior |
| Floor edges / rim joist | High | CI wrapping rim joist area |
| Window frames (aluminum) | Very High | Thermally broken frames or fiberglass |
| Shelf angles (masonry) | Very High | Insulated standoff clips (Thermomass, Schock Isokorb) |
| Balcony penetrations | Extreme | Structural thermal breaks (Schock Isokorb) |
| Foundation-to-wall junction | High | CI lapping from wall to foundation |
| Parapet walls | High | CI wrapping top of wall continuously |
| Structural connections through CI | Variable | Fiberglass or engineered plastic girts |

### Continuous Insulation (CI) Principles

- CI = insulation installed at a constant thickness across ALL structural members without thermal bridging
- Installing CI with adhesives rather than metal screws reduces point thermal bridges
- Non-conductive girts (hardened polyurethane) eliminate thermal bridging at attachment points
- CI alone is not sufficient; combine with advanced framing, high-performance fenestration, and thermal breaks

### How to Show CI in Details
- Draw CI as a continuous unbroken layer on the exterior of structural sheathing
- Use consistent hatch pattern (diagonal lines or dots) through studs without interruption
- Show CI extending past all structural elements: rim joists, sill plates, roof connections
- At windows: show CI returning to window frame (insulated rough opening jamb extension)
- Annotate: "Continuous insulation — no gaps at structural members"

### IECC 2021 CI Requirements Summary

| Climate Zone | Wall Options (Cavity + CI) |
|-------------|---------------------------|
| 1 | R-13 cavity or 0+R-10ci |
| 2 | R-13 cavity or 0+R-10ci |
| 3 | R-20 or R-13+R-5ci or 0+R-15ci |
| 4 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci |
| 5 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci |
| 6 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci |
| 7-8 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci |

---

## 4. Sealant Joint Design

### Width-to-Depth Ratio (The Golden Rule)

**Sealant depth = 1/2 sealant width (2:1 width-to-depth ratio)**

The hourglass-shaped sealant profile maximizes movement capacity and adhesion.

| Joint Width | Sealant Depth | Backer Rod Diameter |
|-------------|---------------|-------------------|
| 1/4" (6mm) | 1/8" (3mm) minimum 1/4" | 5/16" (8mm) |
| 3/8" (10mm) | 3/16" (5mm) | 1/2" (13mm) |
| 1/2" (13mm) | 1/4" (6mm) | 5/8" (16mm) |
| 3/4" (19mm) | 3/8" (10mm) | 1" (25mm) |
| 1" (25mm) | 1/2" (13mm) max | 1-1/4" (32mm) |
| >1" | 1/2" (13mm) max | 25% larger than joint |

### Key Design Rules

- **Minimum sealant depth:** 1/4" (6mm) for adequate adhesion
- **Minimum joint width:** 1/4" — narrower joints cannot accommodate movement
- **Maximum practical width:** 1/2" for standard installation; wider requires engineering
- **Backer rod diameter:** 25% larger than joint width for snug compression fit
- **Backer rod type:** Closed-cell polyethylene (most common); open-cell for deep joints
- **Bond breaker tape:** Use where joint is too shallow for backer rod (prevents 3-sided adhesion)
- **Three-sided adhesion is ALWAYS wrong** — sealant must bond to two opposing surfaces only

### Joint Sizing for Movement

**Joint width = 4x expected movement**

Example: Window casement expects 1/8" thermal movement --> Joint width = 1/2"

### Application Rules

- Apply at average temperature conditions (not extreme hot or cold)
- Substrates must be clean, dry, and primed if required by manufacturer
- Never tool sealant with a finger (saliva breaks bond) — use proper tooling spatula
- Sealant is NOT caulk; different products for different applications
- Polyurethane sealant for most construction joints (ASTM C920, Type S, Grade NS, Class 25 minimum)
- Silicone for glass-to-metal joints and where UV exposure is extreme

### Common Sealant Failures

1. **Three-sided adhesion** — Sealant bonds to back of joint, restricting movement --> cohesive failure
2. **Wrong width-to-depth ratio** — Too deep, sealant tears; too shallow, sealant pops off
3. **Dirty/wet substrate** — Adhesive failure at bond line
4. **Incompatible materials** — Silicone on porous substrates without primer, oil-based on foam
5. **Applied at temperature extreme** — Joint at maximum compression or extension during cure

---

## 5. Window & Door Openings

### The Most Leak-Prone Detail in Any Building

Windows and doors account for the majority of water intrusion claims. Every opening interrupts the WRB, air barrier, and thermal envelope simultaneously.

### Rough Opening Preparation

- Opening sized 1/2" larger than window frame (1/4" gap all around)
- Check plumb and level before flashing
- Clean all dust and debris from framing surfaces
- Prime all surfaces that will receive self-adhered membrane

### Flashing Installation Sequence (Bottom-Side-Top, Always)

**Step 1: Sill Pan Flashing**
- Self-adhered membrane or liquid-applied flashing
- Extend minimum 6" up each jamb
- Back dam: strip of wood or beveled siding at interior edge of sill
- Slope sill pan toward exterior (minimum 5-degree slope)
- **DO NOT caulk across the sill** — must allow drainage
- One continuous piece at corners to prevent leaks

**Step 2: Window Installation**
- Apply sealant at interior face of nail fin (jambs and head ONLY, not sill)
- Shim level and square
- Fasten per manufacturer's specifications
- Sealant should bleed from pre-punched holes (confirms coverage)

**Step 3: Jamb Flashing**
- 9"-wide self-adhered membrane strips
- Extend below sill pan flashing at bottom
- Extend approximately 9" above window at top
- Lap OVER nail fin at jambs

**Step 4: Head Flashing**
- Must lap OVER the nail fin (never behind it)
- Extend to cover jamb flashing on both sides
- Metal drip edge above head flashing (optional but best practice)

**Step 5: WRB Integration**
- WRB laps BEHIND sill flashing (water drains over WRB below)
- WRB laps OVER head flashing (sheds water over the flashing)
- WRB either behind or over jamb flashing (varies by system)
- Cut WRB in modified-I pattern at opening before starting

### Air Barrier at Rough Opening

- Wrap rough opening with air barrier membrane BEFORE window installation
- Membrane must be continuous with wall air barrier (no interruption)
- Window primary seal bonds directly to air barrier material
- Metal flashing is PART OF the air barrier, not separate from it
- Use gussets at all corners to prevent pinholes
- Press all pieces with J-roller; apply sealant bead at all membrane terminations

### Critical Dimensions

| Element | Minimum Dimension |
|---------|------------------|
| Sill pan flashing up jambs | 6" |
| Jamb flashing above window | 9" |
| WRB lap over head flashing | 4" |
| Gap around window frame | 1/4" all sides |
| Sealant bead at nail fin | Continuous |
| Back dam height at sill | 1" minimum |

### Standards Reference
- ASTM E2112 — Standard Practice for Installation of Exterior Windows, Doors, and Skylights
- AAMA 2400 — Standard Practice for Installation of Windows with Flanged Mounting Fins

---

## 6. Roof-to-Wall Transitions

### The Most Vulnerable Junction in Roofing

Roof-to-wall transitions combine gravity drainage, wind-driven rain exposure, thermal movement, and multiple material interfaces. Every roofing failure investigation starts here.

### 6.1 Parapet Walls

#### Components (inside to outside, bottom to top)
1. Roof membrane (extends up wall face)
2. Cant strip at base (45-degree transition)
3. Base flashing (membrane or metal, minimum 8" above roof surface)
4. Counterflashing (covers top of base flashing)
5. Through-wall flashing (at counterflashing reglet level)
6. Parapet wall construction (masonry or framed)
7. Air/vapor barrier (continuous from wall through parapet)
8. Insulation (CI wrapping entire parapet to prevent thermal bridge)
9. Coping (cap flashing with drip edges on BOTH sides)

#### Cant Strip Specifications
- Standard size: 4" x 4" (creating 45-degree slope)
- Material: Rigid insulation, wood (pressure-treated), or perlite
- Purpose: Prevent sharp 90-degree bend in roofing membrane
- Membrane must not bend sharper than 45 degrees at any point

#### Base Flashing Height
- **Minimum 8"** above finished roof surface (measured from top of cant strip for membrane roofs)
- For steep-slope flashing: minimum 4" height x 4" width
- Higher in areas with snow accumulation or ponding risk

#### Coping Requirements
- Overhang both sides of parapet by minimum 2"
- Drip edge (hemmed or bent lip) on BOTH interior and exterior faces
- Maximum joint spacing: 10 feet (expansion joints for thermal movement)
- Slope toward roof side (interior) for drainage
- Joints sealed or gasketed; end dams at terminations
- Material: minimum 24-gauge galvanized steel, aluminum, or copper

#### Counterflashing
- Set in reglet (saw-cut groove in masonry) or surface-mounted with termination bar
- Overlap base flashing minimum 4"
- Allow 1" clearance above roof surface for thermal movement
- Seal reglet with polyurethane sealant after counterflashing installation

### 6.2 Eave Details

#### Vented Attic Eave
1. Roof sheathing extends to fascia
2. Drip edge at eave (metal, extends under first course of shingles and over fascia)
3. Ice and water shield: minimum 24" from exterior wall line (or 36" in cold climates)
4. Underlayment over ice and water shield, lapped shingle-fashion
5. Air barrier at top plate: sealed between wall top plate and roof sheathing
6. Insulation baffles at each rafter bay (maintain 1" minimum ventilation channel)
7. Soffit venting: 50% of required net free area at intake (balance with ridge exhaust)
8. Blocking or baffles to prevent insulation from blocking soffit vents

#### Air Barrier Transition at Eave
- Install drywall or air barrier membrane BEFORE soffit framing
- Seal between wall top plate and ceiling air barrier
- Extend wall air barrier up and over top plate to meet ceiling air barrier
- At dropped soffits/ceilings: maintain air barrier plane at ceiling level (not soffit level)

### 6.3 Roof-Wall Intersection (Sloped Roof Meeting Wall)

#### Step Flashing
- Individual pieces of L-shaped metal flashing (typically 4" x 4" x 8" long)
- Each piece laps the one below by minimum 2"
- Installed simultaneously with each course of shingles
- Step flashing extends under siding/cladding and over shingles
- Counterflashing or siding covers the vertical leg

#### Kick-Out Flashing
- **Required at every roof-wall intersection that terminates at an eave**
- Diverts water from wall into gutter
- Absence of kick-out flashing is one of the most common causes of wall rot
- Pre-formed metal pieces available (e.g., DCI SmartFlash)
- Minimum 4" kick-out extension

---

## 7. Foundation-to-Wall Transitions

### 7.1 Slab-on-Grade to Wall

#### Critical Elements
1. **Vapor barrier under slab:** Minimum 10-mil polyethylene (15-mil preferred), lapped 6" at seams, sealed
2. **Slab edge insulation:** Per climate zone requirements
3. **Termite inspection gap:** Minimum 3" clearance between any covering material and top of foundation wall (required in termite zones including all of Florida)
4. **Moisture barrier at grade line:** Foundation waterproofing or dampproofing terminates 6" minimum above finished exterior grade
5. **Flashing at base of wall:** Through-wall flashing at bottom of wall assembly, extending over foundation ledge
6. **Weep holes above base flashing:** First course of masonry veneer
7. **Sill gasket:** Foam sill seal between wood sill plate and concrete

#### Dampproofing vs. Waterproofing
| | Dampproofing | Waterproofing |
|---|---|---|
| **Purpose** | Resists moisture in soil | Resists hydrostatic pressure |
| **Required when** | Well-drained soil, low water table | High water table, clay soil, habitable below-grade space |
| **Material** | Bituminous coating, 1 coat | Sheet membrane, multi-coat fluid-applied |
| **Code reference** | IRC R406.1 | IRC R406.2 |

### 7.2 Below-Grade Waterproofing

#### Termination Height
- Waterproofing extends from top of footing to minimum 6" above finished exterior grade
- Where habitable space is below grade: extend to 12-24" above grade
- Termination bar at upper edge with sealant bead

#### Protection Board
- XPS rigid insulation or proprietary drainage/protection board over membrane
- Protects membrane from backfill damage (especially rocky soil)
- Drainage mat (dimpled HDPE membrane) over protection board channels water to perimeter drain

#### Perimeter Drain
- 4" perforated pipe at or below footing level
- Surrounded by washed gravel (no fines)
- Filter fabric wrapping to prevent soil migration
- Slope to daylight or sump pit (minimum 1/8" per foot)

### 7.3 Crawl Space Wall Detail

#### Closed/Conditioned Crawl Space
1. Vapor retarder on ground: minimum 6-mil poly, sealed to foundation wall with mastic
2. Foundation wall insulation: rigid foam or closed-cell SPF on interior
3. **Termite inspection gap:** 3" minimum between top of insulation and wood framing
4. **Wicking gap:** 3" between bottom of wall insulation and ground
5. Continuous termite shield (metal) at top of masonry wall under sill plate
6. Air sealing at sill plate and rim joist
7. Conditioned air supply: sized per ASHRAE 62.2

#### Vented Crawl Space
1. Vapor retarder on ground: minimum 6-mil poly, overlapped 6" and taped
2. Floor insulation between joists (R-19 to R-30 depending on climate zone)
3. Vent openings: 1 sq ft per 150 sq ft of floor area (or 1:1500 with vapor retarder)
4. Foundation wall uninsulated (to allow drying)

### 7.4 Insulation Continuity at Foundation

- Wall CI must extend down to overlap with foundation insulation
- Transition detail: CI terminates at grade with protective cladding (stucco, metal channel, cement board)
- Below grade: rigid insulation (XPS preferred for moisture resistance) extends to top of footing
- No gap between wall CI and foundation insulation

---

## 8. Through-Wall Flashing & Masonry Veneer

### Through-Wall Flashing Locations (Required)

Flashing is required at EVERY location where water might enter the masonry wall:
- Base of wall (above foundation/grade)
- Above all window and door heads (lintels)
- Below all window sills
- At shelf angles (every floor line in multi-story)
- At roof-wall intersections
- At all penetrations through the wall
- At parapet copings

### Flashing Materials
- **Copper:** Most durable, expensive; minimum 16 oz
- **Stainless steel:** Excellent durability; minimum 26-gauge
- **Rubberized asphalt membrane:** Flexible, self-sealing; minimum 40 mil
- **EPDM:** Good flexibility; requires adhesive bonding
- **Combination:** Metal with rubberized asphalt coating (best of both)

### Flashing Installation Rules

1. **Extend through full depth of wall** from exterior face to beyond inner face of cavity
2. **Turn up minimum 8" on backup wall** (sheathing/CMU/concrete)
3. **End dams at flashing terminations** — turn up minimum 2" at ends to prevent water running off edge
4. **Lap joints minimum 6"** with mastic sealant between lapped sections
5. **WRB laps over top of flashing turn-up** minimum 4"
6. **Do not puncture flashing** with fasteners below the turn-up line
7. **Slope flashing toward exterior** (drainage direction)

### Weep Hole Specifications

| Parameter | Requirement |
|-----------|------------|
| Location | Immediately above every flashing line |
| Spacing | Maximum 24" o.c. (some codes: 33" o.c. max) |
| Minimum diameter | 3/16" |
| Type options | Open head joints, tubes, wicks, or proprietary vents |
| Bottom of wall | First course above grade flashing |
| Above windows | First course above lintel flashing |
| At shelf angles | First course above shelf angle flashing |

### Drainage Cavity (Air Space)

| Cladding Type | Minimum Cavity | Notes |
|---------------|---------------|-------|
| Brick veneer | 1" (25mm) | Code minimum; 2" preferred for drainage + mortar droppings |
| Stone veneer | 1" (25mm) | Same as brick |
| Stucco (traditional) | 1/16" to 1/8" (2-3mm) | Created by two layers of building paper |
| Wood/fiber cement siding | 3/8" (10mm) | Rainscreen mat or furring strips |
| Metal panels | 3/4" to 1" | Typically on girt system |

### Mortar Dropping Prevention
- Mortar collection device at base of cavity (mesh or board)
- Cavity must not be bridged by mortar
- Keep cavity clean during construction
- Inspect weep holes after completion

---

## 9. Florida / Hurricane / HVHZ Specific

### 9.1 High-Velocity Hurricane Zone (HVHZ)

**Applies to:** Miami-Dade and Broward Counties ONLY

**Design wind speeds:** 170-200+ mph (ASCE 7-22 Risk Category II)

#### Wall Construction Requirements (HVHZ)
- Exterior CMU: minimum nominal 8" thickness
- Frame walls: minimum 19/32" CD Exposure 1 plywood sheathing
- Frame walls clad with wire lath and stucco
- Alternative: minimum 24-gauge rib deck cladding

#### Product Approval
- ALL building products must have Miami-Dade NOA (Notice of Acceptance)
- Must pass TAS 201, 202, 203 (debris impact + wind uplift tests)
- Impact-rated glazing OR approved protective systems (shutters/screens) required

### 9.2 Hurricane Strap / Tie Details

#### Connection Types (Weakest to Strongest)

| Type | Description | Typical Uplift Capacity |
|------|------------|------------------------|
| Toe-nailed | 3 nails through rafter to plate | ~200 lb (inadequate for hurricane zones) |
| Hurricane clip (H2.5A) | Single-sided metal clip, 4 nails | 565 lb |
| Hurricane wrap (H10A) | Wraps over top of rafter, nails both sides | 1,040 lb |
| Engineered strap (MSTA/LSTA) | Continuous strap, multiple nails each end | 1,500-2,500+ lb |

#### Material Specifications
- Minimum 18-gauge galvanized steel (20-gauge for some retrofit applications)
- Screws: minimum #8, head diameter minimum 0.3"
- Screw length per manufacturer tables
- Straps may be twisted 90 degrees + one 90-degree bend at framing transitions

#### Continuous Load Path
- The load path must be continuous from roof to foundation
- Roof-to-wall (hurricane straps)
- Wall-to-floor (hold-downs, anchor bolts)
- Floor-to-foundation (anchor bolts, embedded straps)
- Any break in the load path = catastrophic failure in high wind

### 9.3 Roof Sheathing (Florida High-Wind)

| Element | Requirement |
|---------|------------|
| Material | 19/32" (nominal 5/8") plywood or OSB, Exposure 1 rated |
| Nail type | Ring-shank (ASTM F1667 RSRS-01), 2-3/8" length, 0.113" diameter |
| Edge nailing | 6" o.c. along all panel edges (rafters/trusses) |
| Field nailing | 6" o.c. (high-wind); 12" o.c. permitted in lower wind zones |
| Panel gaps | 1/8" between panels for expansion |

#### Underlayment (FBC Requirements)
- Attachment: corrosion-resistant fasteners, 12" o.c. between laps
- End/side laps: fastened 6" o.c.
- Cap nails: annular ring or deformed shank, minimum 1" cap diameter
- At wind speeds >= 170 mph: METAL caps required (not plastic)

### 9.4 Impact Window Installation (Florida)

#### Flashing Requirements
- Flashing applied "shingle-fashion" per IRC R703.4
- Each layer overlaps the one below
- Flashing extends to surface of exterior wall finish
- Liquid flashing on concrete/CMU; flexible membrane on wood framing
- Sealant compatibility with flashing material verified

#### Inspection Points
- Model number verification against NOA
- Fastener pattern matches manufacturer specification
- Sealant type and placement
- Flashing integration with WRB
- Structural attachment to reinforced opening

### 9.5 Termite Requirements (Florida)

- **Minimum 3" inspection gap** between any covering material and wood framing
- Continuous metal termite shield at top of masonry wall under sill plate
- Pre-treat soil under and around foundations
- Pressure-treated lumber for all ground-contact and near-ground applications
- Annual inspection access must be maintained at all foundation perimeter

---

## 10. Common Failure Points & Defect Analysis

### Failure Statistics

From forensic analysis of building envelope construction defects:

| Defect Type | Prevalence in Litigation |
|-------------|------------------------|
| Penetrations not sealed | 78% of cases |
| Sealant joints missing or deficient | 78% of cases |
| Improper WRB integration/lapping | 67% of cases |
| Window installation issues | Top source of water intrusion claims |
| Roofing/flashing defects | Primary source of water intrusion |

### Top 10 Envelope Detail Errors

1. **Reverse lapping** — Upper material tucked behind lower material instead of shingling over it
2. **Missing kick-out flashing** — At roof-wall intersection terminating at eave, water sheets down wall
3. **No sill pan at windows** — Water penetrates beneath window and enters wall cavity
4. **Head flashing behind nail fin** — Directs water behind window instead of over it
5. **Caulk across window sill** — Traps water in sill pan with no drainage path
6. **Discontinuous air barrier at rim joist** — Massive air leakage, condensation, mold
7. **Three-sided sealant adhesion** — Sealant bonds to back of joint, fails in tension
8. **Missing weep holes** — Water trapped in wall cavity above flashing, no escape route
9. **Thermal bridge at shelf angle** — Condensation line across building face at every floor
10. **Counterflashing not extending over base flashing** — Water enters behind base flashing

### Environmental Degradation Factors

| Factor | Effect on Envelope | Mitigation |
|--------|-------------------|------------|
| UV radiation | Degrades sealants, membranes, coatings | UV-stable materials; paint/cladding protection |
| Freeze-thaw cycles | Enlarges cracks, spalls masonry, breaks sealant bonds | Proper drainage, flexible sealants, air-entrained mortar |
| Wind-driven rain | Forces water through tiny openings | Pressure-equalized rainscreen, redundant barriers |
| Thermal cycling | Expands/contracts joints, fatigues connections | Expansion joints every 10' on copings; flexible sealants |
| Salt spray (coastal) | Corrodes metal, degrades mortar | Stainless steel or hot-dip galvanized; marine-grade sealants |
| Acid rain | Attacks limestone, marble, zinc coatings | Sacrificial coatings; compatible material selection |

---

## 11. IECC 2021 Insulation Requirements by Climate Zone

### Complete Table

| CZ | Ceiling | Wall (Options) | Floor | Basement Wall | Slab | Crawl Space |
|----|---------|---------------|-------|---------------|------|-------------|
| 1 | R-30 | R-13 or 0+R-10ci | R-13 | 0 | 0 | 0 |
| 2 | R-38 | R-13 or 0+R-10ci | R-13 | 0 | 0 | 0 |
| 3 | R-49 | R-20 or R-13+R-5ci or 0+R-15ci | R-19 | R-5/R-13 | R-5ci or R-13f | R-5ci or R-13f |
| 4 | R-60 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci | R-19 | R-10/R-13 | R-10ci or R-13 | R-10, 2ft |
| 5 | R-60 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci | R-30 | R-15ci or R-19 or R-13+R-5ci | R-10ci, 4ft | R-15ci or R-19 or R-13+R-5ci |
| 6 | R-60 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci | R-30 | R-15ci or R-19 or R-13+R-5ci | R-10ci, 4ft | R-15ci or R-19 or R-13+R-5ci |
| 7-8 | R-60 | R-30 or R-20+R-5ci or R-13+R-10ci or 0+R-20ci | R-38 | R-15ci or R-19 or R-13+R-5ci | R-10ci, 4ft | R-15ci or R-19 or R-13+R-5ci |

**Notes:**
- "ci" = continuous insulation
- "f" = full height of foundation wall
- Slab depth = depth of insulation below grade at slab edge
- CZ = Climate Zone per IECC county-level maps
- **Florida:** Mostly CZ 1 (south) and CZ 2 (north)
- **Idaho (Sandpoint):** CZ 5 or CZ 6

---

## Appendix A: Drainage Plane Vapor Permeance

| Material | Vapor Permeance | Air Barrier? |
|----------|----------------|-------------|
| Asphalt-saturated felt (15#) | 5-10 perms (wet) | No |
| Building paper (Grade D) | 5+ perms | No |
| Tyvek HomeWrap | 58 perms | Yes |
| Tyvek CommercialWrap | 28 perms | Yes |
| Self-adhered membrane (peel-and-stick) | <0.1 perms | Yes |
| Fluid-applied WRB (vapor-open) | 10-15 perms | Yes |
| Fluid-applied WRB (vapor-closed) | <1 perm | Yes |
| Rigid XPS (1") | 1.0 perm | Depends on joints |
| Rigid EPS (1") | 2.0-5.0 perms | Depends on joints |
| Rigid polyiso (foil-faced, 1") | <0.1 perm | Yes (with taped joints) |

## Appendix B: Drawing Conventions for Envelope Details

### Standard Symbols in Detail Drawings

| Element | Drawing Convention |
|---------|-------------------|
| Air barrier | Bold continuous line, red in colored drawings; annotated "AIR BARRIER — CONTINUOUS" |
| Vapor retarder | Dashed line with VR label |
| WRB/drainage plane | Wavy or zigzag line behind cladding |
| Insulation (batt) | Wavy/scribble fill between framing |
| Insulation (rigid/CI) | Diagonal crosshatch or dot pattern, continuous through studs |
| Sealant | Filled black circle or hourglass shape at joint |
| Backer rod | Open circle behind sealant |
| Flashing (metal) | Heavy line with arrow showing drainage direction |
| Flashing (membrane) | Thick dashed line with label |
| Slope/drainage direction | Arrow with slope ratio notation |
| Thermal break | Zigzag break symbol in structural member |

### Annotation Requirements

Every envelope detail MUST annotate:
1. Air barrier location and continuity
2. Vapor retarder location (if applicable)
3. Insulation type and R-value
4. Flashing material and extent
5. Sealant joint dimensions and type
6. Drainage direction arrows
7. Weep hole locations
8. Fastener type and spacing (for structural connections)
9. Slope dimensions on all horizontal surfaces
10. Reference to specification section

## Appendix C: Quick Reference — Minimum Dimensions

| Element | Minimum Dimension |
|---------|------------------|
| WRB horizontal lap | 6" |
| WRB vertical lap | 4" |
| Flashing turn-up on backup wall | 8" |
| Flashing end laps | 6" with mastic |
| Flashing end dams | 2" turn-up |
| Base flashing height (membrane roof) | 8" above roof surface |
| Step flashing overlap | 2" minimum |
| Kick-out flashing extension | 4" minimum |
| Coping overhang | 2" both sides |
| Coping expansion joint spacing | 10' maximum |
| Drainage cavity (brick veneer) | 1" minimum |
| Drainage cavity (rainscreen siding) | 3/8" minimum |
| Sealant minimum depth | 1/4" (6mm) |
| Sealant joint minimum width | 1/4" (6mm) |
| Termite inspection gap | 3" (Florida/termite zones) |
| Waterproofing above grade | 6" minimum |
| Ice and water shield from exterior wall | 24" minimum (36" cold climate) |
| Roof sheathing panel gap | 1/8" |
| Sill pan flashing up jambs | 6" minimum |
| Window rough opening gap | 1/4" all sides |

---

## Sources

### Water Management
- [Benjamin Obdyke — The 4 Ds of Moisture Management](https://benjaminobdyke.com/insights/the-4-ds-of-moisture-management-for-wall-solutions/)
- [WBDG — Moisture Management Strategies](https://www.wbdg.org/resources/moisture-management-strategies)
- [Building Enclosure Online — Mechanisms of Moisture Intrusion](https://www.buildingenclosureonline.com/articles/85585-the-mechanisms-of-moisture-intrusion)
- [Weathertight.org.nz — The 4 Ds](https://www.weathertight.org.nz/new-buildings/basic-weathertight-design-principles/the-4-ds-deflection-drainage-drying-and-durability/)

### Window Flashing
- [VERTEX — Window Flashing 101](https://vertexeng.com/insights/window-flashing-101-the-proper-way-to-flash-a-residential-finned-window/)
- [Building America Solution Center — Windows Fully Flashed](https://basc.pnnl.gov/resource-guides/windows-and-doors-are-fully-flashed)
- [NAHB — Window and Door Flashing Code Requirements](https://www.nahb.org/-/media/NAHB/advocacy/docs/top-priorities/codes/technotes/tn05-window-and-door-flashing-201705.pdf)
- [Fine Homebuilding — Installing and Flashing Windows](https://www.finehomebuilding.com/project-guides/windows-doors/installing-and-flashing-windows-correctly)
- [Henry — Window and Door Flashing Best Practices](https://www.henry.com/knowledge-center/residential-blog/window-and-door-flashing-best-practices/)

### Air Barriers
- [Building Science Corp — BSD-104: Understanding Air Barriers](https://buildingscience.com/documents/digests/bsd-104-understanding-air-barriers)
- [WBDG — Air Barrier Systems in Buildings](https://www.wbdg.org/resources/air-barrier-systems-buildings)
- [Siplast — Air Barrier Transitions](https://www.siplast.com/blog/building-enclosure/what-architects-should-know-about-air-barrier-transitions-281474980418303)
- [475 Supply — Air Barrier Transitions: Foundation to Wall](https://475.supply/blogs/design-construction-resources/air-barrier-transitions-simplified-foundation-to-wall)
- [Construction Specifier — Maintaining Continuity at Transitions](https://www.constructionspecifier.com/maintaining-continuity-transitions/2/)

### Thermal Bridging
- [Continuous Insulation.org — Thermal Bridging Prevention](https://www.continuousinsulation.org/thermal-bridging-prevention)
- [Passive House Accelerator — Six Things to Know About Thermal Bridging](https://passivehouseaccelerator.com/articles/six-things-to-know-about-thermal-bridging)
- [Build With Rise — Thermal Bridging and How to Reduce It](https://www.buildwithrise.com/stories/thermal-bridging)

### Sealant Joints
- [Hammer & Hand — Sealant Joint Design](https://hammerandhand.com/best-practices/2-1-sealant-joint-design/)
- [NEMPAL — Sealant Joint Width and Depth](https://nempal.com/howto/how-to-determine-the-width-and-depth-of-a-sealant-joint/)
- [NIH — Sealant Joints Part 2: Joint Design](https://orf.od.nih.gov/TechnicalResources/Documents/News%20to%20Use%20PDF%20Files/2021%20NTU/Sealant%20Joints%20%E2%80%93%20Part%202%20Joint%20Design-March%202021%20News%20to%20Use_508.pdf)

### Drainage Planes & Masonry
- [Building Science Corp — BSD-105: Understanding Drainage Planes](https://buildingscience.com/documents/digests/bsd-105-understanding-drainage-planes)
- [Masonry Technology Inc — Rainscreen 101](https://www.mtidry.com/rainscreen-101)
- [CMHA — Flashing Details for Concrete Masonry Walls](https://www.masonryandhardscapes.org/resource/tek-19-05a/)

### Roof Transitions
- [GAF — Roof to Wall Flashing Details](https://www.gaf.com/en-us/blog/commercial-roofing/roof-to-wall-flashing-why-details-matter-for-single-ply-roofing-systems-281474980098152)
- [Building Enclosure Online — Coping-to-Wall Termination](https://www.buildingenclosureonline.com/articles/82668-roofing-detail-coping-to-wall-termination)
- [Tremco — Parapet to Wall Detail](https://www.tremcosealants.com/blog/parapet-to-wall-detail-the-architects-guide)
- [Roofing Elements — Flashings on a Parapet Wall](https://roofingelementsmagazine.com/joe-knows-flashings-on-a-parapet-wall/)

### Foundation
- [Building Enclosure Online — Waterproofing Termination at Foundation](https://www.buildingenclosureonline.com/articles/86279-waterproofing-detail-termination-at-foundation)
- [DOE — Building Foundations Handbook](https://foundationhandbook.ornl.gov/handbook/section3-1-insulation.shtml)
- [UpCodes — Foundation Waterproofing](https://up.codes/s/foundation-waterproofing-and-dampproofing)
- [Crawl Space Ninja — Termite Inspection Gap](https://crawlspaceninja.com/blog/crawl-space-termite-inspection-gap/)

### Florida / Hurricane
- [Florida Building Code — HVHZ](https://www.floridabuilding.org/fbc/thecode/2013_Code_Development/HVHZ/FBCB/Chapter_16_2010.htm)
- [UpCodes — HVHZ Sheathing](https://up.codes/s/high-velocity-hurricane-zones-sheathing)
- [Simpson Strong-Tie — H2.5A Hurricane Tie](https://www.strongtie.com/seismicandhurricaneties_strapsandties/h25a_htie/p/h25a)
- [Simpson Strong-Tie — H10A Hurricane Tie](https://www.strongtie.com/seismicandhurricaneties_strapsandties/h10a_htie/p/h10a)
- [FBC Roofing Fact Sheet](https://www.floridabuilding.org/fbc/thecode/2020_7edition/Roofing_Fact_Sheet-2_column_format052820Final.pdf)
- [Design Lines — Window Installation for Florida Homes](https://designlines.blog/2025/02/18/proper-window-installation-for-florida-homes-preventing-water-damage-and-ensuring-hurricane-protection/)

### IECC / Energy Code
- [Building America Solution Center — IECC Insulation Requirements](https://basc.pnnl.gov/information/2009-2021-iecc-and-irc-minimum-insulation-requirements-new-homes)
- [IECC 2021 Chapter 4 RE](https://codes.iccsafe.org/content/IECC2021P1/chapter-4-re-residential-energy-efficiency)

### Building Envelope Failures
- [Beacon Consulting — 10 Common Building Envelope Issues](https://www.beacon.ws/news-events/beacon-news/staff-article-construction-defects-april-2025)
- [Robson Forensic — Building Enclosure Defects](https://www.robsonforensic.com/articles/building-enclosure-defects-expert-witness)
- [VERTEX — Building Envelope Issues in Litigation](https://vertexeng.com/insights/building-envelope-issues-within-construction-defect-litigation/)
- [Superstructures — Why Do Envelopes Fail](https://www.superstructures.com/restoration-101/why-do-envelopes-fail/)
