1 Scope
NOTE This standard covers the supply and installation of factory-assembled unit skylights and tubular daylighting devices set into sloped or flat roof assemblies to introduce daylight through the roof plane. (1.1)
NOTE Unit skylights are pre-engineered, factory-glazed assemblies labeled to a North American Fenestration Standard (NAFS) performance grade, distinct from site-glazed sloped glazing built up from individual lites. (1.2)
NOTE The following mounting and operating configurations are within scope: (1.3)
- Curb-mounted fixed units set on a site-built or manufacturer-supplied insulated curb.
- Deck-mounted (self-flashing) fixed units whose integral flange flashes directly to the roof deck on steep-slope roofs.
- Curb-mounted operable (venting) units with manual crank, chain-drive, or electric operators, including roof windows on steep-slope residential roofs.
- Single-, double-, and triple-dome plastic-glazed units and insulating-glass-unit (IGU) glazed units.
- Tubular daylighting devices (TDDs) consisting of a roof dome, reflective tube, and ceiling diffuser.
- Gang or continuous-row units mounted on a common curb or on abutting individual curbs.
NOTE Custom architectural assemblies (barrel vaults, pyramids, and structural glass roofs) that exceed standard catalog products approach curtainwall territory and are outside the scope of this standard. (1.4)
1.5Very large or structurally complex custom assemblies should be specified under Glazing rather than this standard. NOTE Units listed and installed to serve as automatic smoke and heat vents are not unit skylights for the purpose of this standard; they are covered by
Roof Hatches And Smoke Vents.
(1.7) 2 Referenced Standards
2.1Products and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited or a different edition is enforced by the authority having jurisdiction.
2.2Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
NOTE NAFS-26 (AAMA/WDMA/CSA 101/I.S.2/A440-26) is the current edition at the time of writing and supersedes the 2022 edition, but many jurisdictions still reference NAFS-22 until their code cycle updates; the locally adopted edition governs. (2.3)
| Standard |
Title |
| AAMA/WDMA/CSA 101/I.S.2/A440 (NAFS) |
North American Fenestration Standard/Specification for Windows, Doors, and Skylights |
| ASTM E1300 |
Standard Practice for Determining Load Resistance of Glass in Buildings |
| ASTM E2112 |
Standard Practice for Installation of Exterior Windows, Doors and Skylights |
| IBC Section 2405 |
Sloped Glazing and Skylights (Chapter 24) |
| IBC Section 1507.5 |
Skylights and Sloped Glazing (Chapter 15, Roof Assemblies) |
| ASCE 7 |
Minimum Design Loads and Associated Criteria for Buildings and Other Structures |
| NFPA 13 |
Standard for the Installation of Sprinkler Systems |
| OSHA 29 CFR 1926.502 |
Fall Protection Systems Criteria and Practices |
| OSHA 29 CFR 1910.29 |
Fall Protection Systems and Falling Object Protection Criteria |
| NFRC 100 |
Procedure for Determining Fenestration Product U-factors |
| NFRC 200 |
Procedure for Determining Fenestration Product SHGC and Visible Transmittance |
| ASHRAE 90.1 |
Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings |
| ENERGY STAR (Skylights) |
ENERGY STAR Program Requirements for Residential Skylights |
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following action submittals for review before fabrication or ordering:
- Product data for each skylight type, including frame material, glazing makeup, operator type, and accessories.
- Shop drawings showing unit dimensions, curb details, flashing integration, fastening, cricket locations, and condensate provisions.
- NAFS performance label data confirming performance grade, design pressure, and gateway test results for each unit.
- NFRC-certified whole-product U-factor, SHGC, and visible light transmittance values for each glazing configuration.
- Glazing certification identifying glass type (tempered, laminated, heat-strengthened) or plastic type and impact rating for sloped use.
- Fall-protection details for screens, guards, or covers, with the load rating and the party responsible for installation.
- Glazing and finish samples in the specified color and tint.
☑ Product data (each type)
☑ Shop drawings (curb, flashing, fastening)
☑ NAFS performance label data
☑ NFRC U-factor / SHGC / VLT certification
☐ Glazing/plastic type certification (sloped use)
☐ Fall-protection details and load rating
☐ Glazing and finish samples
3.2 Closeout Submittals
3.2.1The Contractor shall submit the following closeout submittals before final acceptance:
- Manufacturer's written product and installation warranties.
- Operation and maintenance data for operable units, operators, sensors, and shades.
- Record documents showing as-installed unit locations, sizes, and accessories.
- Final fall-protection certification confirming installed screens or guards meet the rated load.
☑ Product and installation warranties
☑ Operation and maintenance data
☐ Record documents (as-installed)
☑ Fall-protection certification
3.3.1The Contractor shall submit the following informational submittals when required by the Contract Documents:
- Structural calculations for custom or non-catalog units signed by a licensed engineer.
- Manufacturer's field-service or inspection reports for installed units.
- Energy compliance documentation demonstrating skylight-to-roof ratio and U-factor/SHGC conformance with the adopted energy code.
☐ Structural calculations (custom units)
☐ Field-service / inspection reports
☑ Energy compliance documentation
4 Quality Assurance
NOTE Each unit skylight shall bear a permanent NAFS label identifying the manufacturer, performance grade, design pressure, and the certification or inspection agency. (4.1)
4.2Units shall be certified to the specified NAFS performance grade by an accredited certification and labeling program.
4.3Glazing in sloped applications shall comply with IBC Section 2405.2 for permitted glazing types and, where required, screening or retention against fall-out.
4.4Thermal performance values shall be NFRC-certified whole-product values.
4.5Center-of-glass values shall not be substituted for whole-product values in code or energy-model submittals.
NOTE The installer shall be trained or approved by the skylight manufacturer for the specified product line. (4.6)
4.7A mock-up or first-unit installation should be reviewed and approved before remaining units are installed where the project includes more than ten units or any custom configuration.
5 Environmental and Service Conditions
NOTE Skylights are exposed to the full range of roof-plane loads and environmental stresses: wind uplift and inward pressure, snow and live loads, thermal cycling, ultraviolet exposure, hail, and condensation driven by interior humidity. (5.1)
5.2Design pressure shall be established from the project wind and snow loads determined per ASCE 7 and IBC Chapter 16 for the building height, exposure, and roof zone.
5.3Glazing load resistance shall be verified per ASTM E1300 for glass units under the governing wind and snow load.
NOTE In cold climates, interior humidity contacts cold frame and glazing surfaces and produces condensation that is often mistaken for leakage. (5.4)
5.5Units shall include thermally broken frames and condensate management to prevent moisture damage.
CZ1 - CZ3 (warm / mixed)
CZ4 - CZ5 (mixed / cold)
CZ6 - CZ8 (cold / very cold)
Per drawings — structural roof load schedule (deferred by default)
Per drawings — structural wind design data (deferred by default)
NOTE NAFS classifies fenestration into performance classes R, LC, CW, and AW in ascending order of structural, air, and water severity; the class drives the gateway test pressures and the minimum design pressure. Specifying a residential R-class unit in a commercial, institutional, or high-wind application is a common and serious error, since CW or AW class is required for most commercial and high-exposure projects. (6.1)
6.2Unit skylights shall meet or exceed the specified NAFS performance grade for class and design pressure.
6.3The structural test load shall be not less than 150% of the design pressure without glass breakage or permanent deformation that impairs function.
6.4Water resistance shall be demonstrated at a test pressure of not less than 15% of the design pressure, and not less than 15 psf.
6.5Air infiltration shall not exceed the limit for the specified performance class at the standard test pressure.
○ R (residential)
○ LC (light commercial)
● CW (commercial window)
○ AW (architectural)
0.050.5
Default: 0.3 cfm/ft²
7 Mounting Configuration
7.1 Curb-Mounted Units
NOTE Curb-mounted units set on a raised curb are the standard configuration for flat and low-slope roofs; the curb lifts the unit above the drainage plane and provides a surface for base flashing. (7.1.1)
7.1.2Curb-mounted units shall be set on a curb extending not less than 4 inches (102 mm) above the finished roof plane, per IBC Section 2405.4.
7.1.3On re-roofing projects, curbs should extend not less than 8 inches above the finished roof to maintain base-flashing height over the new assembly.
7.1.4The curb shall be insulated to limit thermal bridging and condensation at the perimeter of the opening.
● Manufacturer-supplied insulated curb
○ Site-built wood curb with separate insulation
○ Site-built steel curb with separate insulation
7.2 Deck-Mounted (Self-Flashing) Units
NOTE Deck-mounted units carry an integral flange that flashes directly into the roof underlayment; they are engineered for steep-slope shingle or tile roofs, not low-slope membrane roofs. (7.2.1)
NOTE Specifying self-flashing units on a low-slope membrane roof voids the roofing waterproofing warranty and is a recurring source of leaks. (7.2.2)
7.2.3Low-slope membrane roofs shall use a curb-mounted unit rather than a deck-mounted (self-flashing) unit.
7.2.4Deck-mounted units shall be installed only on roof slopes of 3:12 or steeper unless the manufacturer certifies a lower slope.
● Curb-mounted
○ Deck-mounted (self-flashing)
8 Glazing
8.1 Glazing Type and Makeup
NOTE Glazing makeup determines thermal performance, light transmittance, and impact resistance; plastic domes offer high transmittance and light weight, while IGUs deliver the lower U-factors required for cold-climate commercial compliance. (8.1.1)
8.1.2Sloped glazing shall be tempered, laminated, or heat-strengthened glass, or an approved plastic, as permitted by IBC Section 2405.2; annealed monolithic glass shall not be used in sloped applications.
8.1.3Where glass could fall from the opening on breakage, the glazing shall be laminated or shall be screened or retained as required by IBC Section 2405.3.
8.1.4Double- and triple-dome and insulating-glass units shall maintain a sealed air or gas space free of internal condensation.
○ Single dome (acrylic or polycarbonate)
● Double dome (acrylic or polycarbonate)
○ Triple dome (acrylic or polycarbonate)
○ Double insulating glass unit (IGU)
○ Triple insulating glass unit (IGU)
Tempered glass
Laminated glass
Heat-strengthened glass
Laminated over tempered
Acrylic
Polycarbonate
Acrylic outer / polycarbonate inner
8.2 Tint, Coating, and Light Transmittance
NOTE Tint and low-emissivity coatings balance daylight against solar heat gain; clear glazing maximizes visible light transmittance, while tints and low-e coatings reduce heat gain and glare. (8.2.1)
8.2.2The low-emissivity coating type and surface shall be selected for the climate, favoring solar-heat-gain control in cooling-dominated climates and heat-loss control in heating-dominated climates.
Clear
Lightly diffused (white translucent)
Bronze tint
Gray tint
○ None
● Solar-control low-e (cooling climates)
○ High-solar-gain low-e (heating climates)
NOTE Energy codes cap skylight U-factor and SHGC by climate zone, and ASHRAE 90.1 limits skylight area to a fraction of the roof to control heat loss and gain; thermal values must come from NFRC whole-product certification, not center-of-glass approximations. (9.1)
9.2The skylight U-factor shall not exceed the maximum permitted for the climate zone and skylight-to-roof ratio by the adopted energy code.
9.3The skylight SHGC shall not exceed the maximum permitted for the climate zone and occupancy by the adopted energy code.
9.4Total skylight area shall not exceed 3% of the gross roof area under ASHRAE 90.1 unless a daylighting-control credit or energy trade-off compliance path is documented.
9.5Frames in climate zones 4 and above shall be thermally broken to meet energy requirements and to control frame condensation.
0.250.7
Default: 0.45 Btu/h·ft²·°F
● 3% (prescriptive, no daylighting controls)
○ 5% (with daylighting controls)
○ Trade-off compliance path
10 Frame, Finish, and Operation
10.1 Frame Material and Finish
NOTE Frame material affects durability, thermal performance, and appearance; thermally broken aluminum is the commercial default, while fiberglass, PVC, and wood-clad frames serve residential and specialty applications. (10.1.1)
10.1.2Aluminum frames in climate zones 4 and above shall incorporate a thermal break.
● Thermally broken aluminum
○ Aluminum (non-thermally-broken)
○ Fiberglass
○ PVC
○ Wood-clad
Clear anodized
Color anodized
Factory-applied fluoropolymer paint
Mill finish
10.2 Operation
NOTE Operable (venting) units provide ventilation and smoke purge but add operator hardware and, for electric units, a power and control rough-in that must be coordinated with the electrical drawings. (10.2.1)
NOTE Omitting the operator power rough-in for electric venting units is a common coordination gap caught at rough inspection; rough-in shall be coordinated with the electrical work before roofing is closed in. (10.2.2)
10.2.3Operable units shall be furnished with the specified operator and weatherstripping rated for the unit's performance grade.
10.2.4Electric venting units shall be provided with the power and low-voltage control rough-in shown on the electrical drawings.
● Fixed (non-venting)
○ Manual crank-operated
○ Chain-drive operated
○ Electric operator
○ Solar-powered electric operator
☐ Rain sensor (auto-close)
☐ Interior blind / shade
☐ Between-pane blind
☑ Insect screen
11 Curb, Flashing, and Condensate Management
11.1 Cricket and Saddle
NOTE A cricket diverts water around the upslope side of a skylight; without it, water ponds against the upslope curb and eventually infiltrates. (11.1.1)
11.1.2An upslope cricket or saddle shall be provided where the unit width exceeds 24 inches and the roof slope is less than 1:2.
● Required (unit width > 24 in)
○ Not required (unit width ≤ 24 in)
○ Required by drawings
11.2 Flashing
NOTE Flashing integrates the unit with the roofing; a frequent failure is that contract documents do not state who fabricates and installs the flashing, leaving the roofing and skylight trades each assuming the other is responsible. (11.2.1)
11.2.2Responsibility for fabricating and installing curb base flashing, counterflashing, and any step or apron flashing shall be assigned explicitly in the Contract Documents.
11.2.3Flashing shall be integrated with the roofing system per Sheet Metal Flashing And Trim and ASTM E2112 to maintain continuity of the water-shedding plane. 11.3 Condensate Management
NOTE Condensate forming on the cold inner surfaces of frame and glazing must be captured and drained; without a weep path it accumulates inside the curb and is reported as a leak, generating callbacks. (11.3.1)
11.3.2Curb-mounted and frame-glazed units shall include interior condensate gutters and a weep drainage path to the exterior.
● Integral condensate gutter with weeps
○ Thermally broken frame with weep path
○ None (warm climate only)
12 Fall Protection
NOTE A skylight in a roof is an opening; OSHA treats it as a fall hazard and requires a screen, guardrail, or cover wherever a worker could fall 4 feet or more, and the responsibility for that protection is frequently left unassigned among the skylight supplier, roofer, and general contractor. (12.1)
12.2Fall protection shall be provided at every skylight opening 4 feet or more above a lower level by an integral screen, a guardrail system, or a cover.
12.3Fall-protection screens and covers shall resist a load of not less than 200 lb applied perpendicularly at any point, per OSHA 29 CFR 1926.502 and 1910.29.
12.4Where a guardrail system is used, the top rail shall be 42 ± 3 inches above the walking surface.
12.5Responsibility for furnishing and installing the fall-protection element shall be assigned explicitly in the Contract Documents.
● Integral skylight screen
○ Separate post-mounted guardrail
○ Safety net / cover
13 Tubular Daylighting Devices
NOTE A tubular daylighting device captures daylight at a roof dome, transmits it down a reflective tube, and distributes it through a ceiling diffuser; TDDs serve spaces where a framed skylight opening cannot be created. (13.1)
13.2TDDs shall be installed with the manufacturer's flashing matched to the roof type and slope.
13.3The reflective tube shall be sealed and insulated where it passes through conditioned and unconditioned spaces to limit condensation and heat transfer.
13.4The ceiling diffuser shall be selected for the required light distribution and, where specified, integral ventilation or electric-light kits.
● Clear impact-rated dome
○ Diffusing dome
○ Low-e coated dome
☐ Daylight dimmer
☐ Integral electric light kit
☐ Integral ventilation
14 Size and Configuration
NOTE Standard catalog sizes carry the shortest lead time; custom and non-catalog units require 8 to 16 weeks of fabrication and shall be identified during procurement planning so they do not delay the schedule. (14.1)
14.2Custom or non-catalog unit sizes and shapes shall be flagged during procurement so their fabrication lead time is incorporated into the construction schedule.
● Single unit
○ Gang (abutting units on common curb)
○ Continuous row
○ Custom (pyramid / barrel-vault / polygonal)
24 × 24
24 × 48
48 × 48
Custom
Per drawings — roof plan skylight schedule (deferred by default)
15 Installation
15.1Skylights shall be installed in accordance with the manufacturer's printed instructions and ASTM E2112.
15.2Units shall not be installed on slopes flatter than the manufacturer's certified minimum; glazed skylights without a curb shall be installed on slopes of not less than 1:4 per IBC Section 2405.3.
15.3Curb-mounted units shall be set on a continuous bed of the manufacturer's specified sealant and fastened to the curb at the spacing shown on the shop drawings.
15.4Flashing shall be lapped to shed water over the downslope roofing and integrated continuously with the roofing system.
15.5Operable units shall be adjusted after installation so they open, close, latch, and weatherseal without binding.
15.6Glazing and frames shall be protected from construction traffic and from sealant, mortar, and roofing-bitumen contamination until final acceptance.
15.7Each installed unit shall be tested for water resistance by a controlled water test where required by the Contract Documents, with no water penetration to the interior.
16 Delivery, Storage, and Handling
16.1Units shall be delivered in the manufacturer's packaging with the NAFS label and glazing identification intact.
16.2Units shall be stored upright and protected from impact, ultraviolet exposure, and ponded water until installation.
16.3Plastic-glazed domes shall be handled to avoid scratching and shall not have protective films removed until after installation.
16.4Damaged units, units with broken seals, or units with delaminated glazing shall be rejected and replaced.
17 Warranty
17.1The manufacturer shall warrant each unit against defects in materials and workmanship for the period specified, and shall warrant insulating-glass and dome assemblies against seal failure and internal condensation.
17.2The installer shall warrant the installation, including flashing integration and water resistance, for the period specified.
17.3Warranty periods shall not be reduced by accessory operators, sensors, or shades furnished with the unit.
18 Spare Parts
18.1The Contractor shall furnish the spare parts and maintenance materials specified for operable units and accessories.
18.2Spare parts shall be furnished in the manufacturer's original packaging and labeled with the unit type they serve.
☐ Spare operator / motor (each operable type)
☑ Spare crank handles
☐ Spare insect screens
☑ Touch-up finish kit
☐ Replacement gaskets / weatherstripping