Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Pre-Engineered Wood Roof Trusses
…299 unchanged lines
### Long-span trusses shall be fabricated with upward camber where required by the truss designer to offset dead-load deflection.
−### Camber builds an upward curve into the truss so that under sustained dead load the bottom chord settles toward level rather than sagging visibly. Spans up to 40 ft commonly need little or none; spans beyond 60 ft may require 1 to 1.5 in. of camber. Camber is set by the truss designer, not assumed by the installer. {note}
−
```datasheet
label: Camber requirement
…6 unchanged lines
```
−# Materials {toc}
+### Camber builds an upward curve into the truss so that under sustained dead load the bottom chord settles toward level rather than sagging visibly. Spans up to 40 ft commonly need little or none; spans beyond 60 ft may require 1 to 1.5 in. of camber. Camber is set by the truss designer, not assumed by the installer. {note}
−## Lumber {toc}
+# Lumber {toc}
−### Chord and web lumber shall be visually graded or machine-rated dimension lumber bearing the grade mark of an ALSC-accredited agency, with design values from the ANSI/AWC NDS-2024 Supplement.
+## Chord and web lumber shall be visually graded or machine-rated dimension lumber bearing the grade mark of an ALSC-accredited agency, with design values from the ANSI/AWC NDS-2024 Supplement.
−### Lumber shall be one of the following species groups: Spruce-Pine-Fir (SPF), Hem-Fir, or Southern Pine, of the grade required by the truss design.
+```datasheet
+label: Chord lumber grade
+type: select
+options:
+ - No. 2 visually graded
+ - No. 1 visually graded
+ - MSR 2400f-2.0E
+ - MSR 2700f-2.2E
+default: No. 2 visually graded
+```
−### No. 2 grade Southern Pine or SPF is the typical chord material for residential spans; machine-stress-rated (MSR) or machine-evaluated-lumber (MEL) grades such as 2400f-2.0E are specified for longer spans where higher stiffness and tension capacity are needed. The truss designer selects the grade to meet the engineered demand, so the specification fixes the acceptable species set rather than dictating a single grade. {note}
+## Lumber shall be one of the following species groups: Spruce-Pine-Fir (SPF), Hem-Fir, or Southern Pine, of the grade required by the truss design.
−### Lumber moisture content at the time of fabrication shall not exceed 19 percent.
−
−### Plates pressed into lumber wetter than 19 percent can loosen as the wood dries and shrinks, reducing joint capacity. Limiting moisture content at fabrication protects the plate-to-wood connection over the service life of the truss. {note}
−
```datasheet
label: Chord lumber species group
…6 unchanged lines
```
−```datasheet
−label: Chord lumber grade
−type: select
−options:
− - No. 2 visually graded
− - No. 1 visually graded
− - MSR 2400f-2.0E
− - MSR 2700f-2.2E
−default: No. 2 visually graded
−```
+## No. 2 grade Southern Pine or SPF is the typical chord material for residential spans; machine-stress-rated (MSR) or machine-evaluated-lumber (MEL) grades such as 2400f-2.0E are specified for longer spans where higher stiffness and tension capacity are needed. The truss designer selects the grade to meet the engineered demand, so the specification fixes the acceptable species set rather than dictating a single grade. {note}
−## Metal Connector Plates {toc}
+## Lumber moisture content at the time of fabrication shall not exceed 19 percent.
−### Metal connector plates shall be formed from galvanized sheet steel conforming to ASTM A653/A653M (with ASTM A924/A924M general requirements), minimum 20 gauge, with a minimum G60 coating.
+## Plates pressed into lumber wetter than 19 percent can loosen as the wood dries and shrinks, reducing joint capacity. Limiting moisture content at fabrication protects the plate-to-wood connection over the service life of the truss. {note}
−### Connector plates shall carry a current ICC-ES evaluation report establishing their lateral resistance and tooth-withdrawal design values.
+# Metal Connector Plates {toc}
−### Connector plates in contact with fire-retardant-treated or preservative-treated lumber, or exposed to weather or wet-service conditions, shall use the heavier coating (G90 or greater) or the stainless-steel plate required by the plate manufacturer's evaluation report for that condition.
+## Metal connector plates shall be formed from galvanized sheet steel conforming to ASTM A653/A653M (with ASTM A924/A924M general requirements), minimum 20 gauge, with a minimum G60 coating.
−### Treatment chemicals and moisture are corrosive to galvanized steel; the standard G60 plate is intended for dry, untreated interior service. Where the plate contacts treated lumber or sees moisture, the manufacturer's evaluation report dictates an upgraded coating or stainless plate, and substituting the standard plate voids the listed capacity. {note}
−
```datasheet
label: Connector plate gauge
…6 unchanged lines
```
+## Connector plates shall carry a current ICC-ES evaluation report establishing their lateral resistance and tooth-withdrawal design values.
+
+## Connector plates in contact with fire-retardant-treated or preservative-treated lumber, or exposed to weather or wet-service conditions, shall use the heavier coating (G90 or greater) or the stainless-steel plate required by the plate manufacturer's evaluation report for that condition.
+
```datasheet
label: Connector plate coating
…6 unchanged lines
```
−## Treated Lumber {toc}
+## Treatment chemicals and moisture are corrosive to galvanized steel; the standard G60 plate is intended for dry, untreated interior service. Where the plate contacts treated lumber or sees moisture, the manufacturer's evaluation report dictates an upgraded coating or stainless plate, and substituting the standard plate voids the listed capacity. {note}
−### Fire-retardant-treated lumber shall be provided where required for IBC Type III exterior walls and other occupancies mandated by the building code.
+# Treated Lumber {toc}
−### Plate-embedment design values for connector plates in fire-retardant-treated lumber shall be established by the treatment's ICC-ES evaluation report.
+## Fire-retardant-treated lumber shall be provided where required for IBC Type III exterior walls and other occupancies mandated by the building code.
−### Generic FRT requirements without a referenced evaluation report are a recurring defect: FRT chemistry reduces the nail-value capacity of connector plates, and only the tested values from the specific treatment's ICC-ES report are valid for design. Specifying "FRT lumber" alone permits an unapproved substitution that the truss capacity does not account for. {note}
+## Plate-embedment design values for connector plates in fire-retardant-treated lumber shall be established by the treatment's ICC-ES evaluation report.
−### Pressure-preservative-treated lumber shall be provided for trusses exposed to weather, in contact with masonry or concrete, or in wet-service conditions, with connector plates upgraded to the coating required for the treatment.
+## Generic FRT requirements without a referenced evaluation report are a recurring defect: FRT chemistry reduces the nail-value capacity of connector plates, and only the tested values from the specific treatment's ICC-ES report are valid for design. Specifying "FRT lumber" alone permits an unapproved substitution that the truss capacity does not account for. {note}
+## Pressure-preservative-treated lumber shall be provided for trusses exposed to weather, in contact with masonry or concrete, or in wet-service conditions, with connector plates upgraded to the coating required for the treatment.
+
```datasheet
label: Lumber treatment
…12 unchanged lines
### The truss spacing, span, and roof pitch shown on the truss design drawings shall match the truss placement plan and the architectural roof geometry.
−### Spacing, span, and pitch are the three parameters that drive every downstream load and member size. Standard residential framing is 24 in. o.c. at a 4:12 to 6:12 pitch over a 28 to 40 ft span; closer spacing or steeper pitch is selected for higher loads, heavier finishes, or architectural ceiling profiles. {note}
−
```datasheet
label: Truss spacing
…37 unchanged lines
```
+### Spacing, span, and pitch are the three parameters that drive every downstream load and member size. Standard residential framing is 24 in. o.c. at a 4:12 to 6:12 pitch over a 28 to 40 ft span; closer spacing or steeper pitch is selected for higher loads, heavier finishes, or architectural ceiling profiles. {note}
+
## Energy Heel {toc}
### Trusses at insulated eaves shall be provided with a raised (energy) heel where required to maintain the full insulation depth over the exterior wall top plate.
−### A standard heel pinches the insulation to almost nothing where the top chord meets the wall, creating a cold edge and condensation risk. The energy heel raises the top-chord/bottom-chord intersection so the specified attic insulation depth continues out over the wall plate; it has been the energy-code-compliant residential default since IECC 2012. {note}
−
```datasheet
label: Heel condition
…15 unchanged lines
```
+### A standard heel pinches the insulation to almost nothing where the top chord meets the wall, creating a cold edge and condensation risk. The energy heel raises the top-chord/bottom-chord intersection so the specified attic insulation depth continues out over the wall plate; it has been the energy-code-compliant residential default since IECC 2012. {note}
+
## Girder Trusses {toc}
…21 unchanged lines
### Each truss shall bear over its full specified bearing length on a continuous support capable of resisting the truss reaction without crushing.
−### Truss bearing shall provide a minimum length of 3.5 in. on a wood top plate, 3.5 in. on steel, and 4 in. on masonry or concrete, unless a greater length is shown on the truss design drawings.
−
−### The bearing length controls the perpendicular-to-grain bearing stress in the wall plate. Long-span trusses carry high reactions concentrated on a short heel, and an undersized plate, header, or beam crushes or splits under that reaction. Where the reaction exceeds the plate capacity, a wider plate, a bearing block, or a steel bearing seat is required. {note}
−
```datasheet
label: Bearing condition
…6 unchanged lines
```
+### Truss bearing shall provide a minimum length of 3.5 in. on a wood top plate, 3.5 in. on steel, and 4 in. on masonry or concrete, unless a greater length is shown on the truss design drawings.
+
```datasheet
label: Minimum bearing length
…7 unchanged lines
```
+### The bearing length controls the perpendicular-to-grain bearing stress in the wall plate. Long-span trusses carry high reactions concentrated on a short heel, and an undersized plate, header, or beam crushes or splits under that reaction. Where the reaction exceeds the plate capacity, a wider plate, a bearing block, or a steel bearing seat is required. {note}
+
## Uplift Tie-Downs {toc}
…107 unchanged lines
## The fabricator shall warrant that the trusses are free from defects in material and workmanship and are fabricated in conformance with the accepted truss design drawings and ANSI/TPI 1-2022.
−## The warranty excludes damage caused by field modification, overloading beyond the design loads, or installation contrary to the manufacturer's instructions and BCSI-2025. {note}
−
```datasheet
label: Fabrication warranty period
…6 unchanged lines
```
+## The warranty excludes damage caused by field modification, overloading beyond the design loads, or installation contrary to the manufacturer's instructions and BCSI-2025. {note}
+
# Spare Parts {toc}
## The fabricator shall furnish engineered repair plate details and any specialty connectors required for anticipated field repairs identified during erection.
## Because field modification of a fabricated truss is prohibited without engineering, the practical "spare part" for a truss roof is a pre-approved repair detail rather than stock components. Keeping repair details and a small reserve of the specified hangers and tie-downs on site avoids a fabrication-plant turnaround when a truss is damaged during construction. {note}