A Bilco Type S roof hatch provides access between a building interior and its roof for maintenance, inspection, and equipment service. It is a steel hatch intended for a range of commercial and institutional applications. Choosing the right model involves more than matching the opening size: buyers also need to check curb height, insulation, ladder or stair access, roof construction, safety requirements, and the project’s specifications. The details below explain what to verify before ordering or installing a Bilco Type S roof hatch.
What Is a Bilco Type S Roof Hatch?
The Bilco Type S is a roof-access hatch with a steel cover and curb. It is designed to provide a weather-resistant opening through a roof while allowing authorized personnel to reach the roof from inside the building. It is commonly specified for commercial, industrial, and institutional buildings, though suitability depends on the building design and required performance.
“Type S” identifies a product line, not a single universal size or configuration. Available dimensions, options, finishes, and details can vary by model and order. For that reason, a project should be checked against Bilco’s current product literature and the exact model’s submittal drawings rather than relying on a general description or an old specification.
The Type S is one option in Bilco’s broader roof-hatch lineup. Other models may use different materials, sizes, or design features. A Type S may be appropriate when a steel hatch fits the project’s durability, cost, and construction requirements; it is not automatically the best choice for every roof or climate.
Key Features and Construction
Bilco Type S hatches are constructed with steel components, including a cover and curb. The product literature for the selected model should be consulted for the precise material thickness, finish, insulation, hardware, and available options. These details matter because they affect strength, corrosion resistance, thermal performance, and compatibility with the surrounding roof assembly.
Roof hatches generally include a curb that supports the cover and raises the opening above the roof surface. The curb must be integrated with the roofing system to help limit water entry. A cover-opening mechanism and hold-open feature are also important: the hatch should be operable by the intended users and remain safely open in accordance with the manufacturer’s instructions.
Depending on the model and order, options may address such needs as interior or exterior operation, security, hardware, safety accessories, or finish. Availability should be confirmed with Bilco or an authorized distributor. Project teams should not assume that a feature is standard simply because it appears on another hatch model or in a different catalog edition.
Sizes and Selecting the Right Opening
Roof-hatch dimensions are specified in different ways, so the terms “nominal size,” “clear opening,” and “rough opening” should not be treated as interchangeable. The clear opening is the usable passage through the hatch. The rough opening is the opening framed into the roof, and it is typically determined from the manufacturer’s dimensional drawings and the project’s structural details.
Before ordering a Bilco Type S, confirm the opening required by the roof-access equipment and the intended use. A person carrying tools or equipment may need more clearance than someone using the hatch for occasional inspection. The selected size must also work with the ladder or stair below, headroom above the access point, roof obstructions, and the route to the hatch.
Use the following checklist to reduce the risk of ordering the wrong unit:
- Measure the framed opening and compare it with the exact model’s approved submittal drawing.
- Confirm clear-opening dimensions rather than relying on a nominal size alone.
- Check curb height and roof build-up, including insulation, cover board, membrane, and flashing details.
- Review the access arrangement, including ladder or stair position, swing clearance, and headroom.
- Verify handling requirements if workers will carry tools or materials through the opening.
Where the hatch is replacing an existing unit, field measurements are essential. Existing openings may not match standard dimensions, and roof repairs can reveal changes in framing or roof thickness. A replacement should not be ordered from the old hatch’s label alone; the opening, curb, and access geometry should be measured and compared with current drawings.
Roof Compatibility and Weatherproofing
A roof hatch is only as reliable as the connection between its curb and the roof. The curb must be properly supported and flashed into the roof system using details suitable for the roofing material. Membrane roofs, built-up roofs, and metal roof assemblies can require different approaches. The hatch manufacturer’s instructions and the roofing-system manufacturer’s requirements should both be reviewed.
Water management is a central part of installation. The roof design should direct water away from the curb rather than allowing ponding around it. The installer must coordinate curb height, flashing, counterflashing where applicable, insulation, and adjacent roof details. Cutting or modifying the curb without manufacturer approval can affect performance and may void warranties.
Thermal performance also deserves attention. A hatch creates an opening in the roof envelope, and the specified insulation and weather seals should suit the building’s energy and condensation-control requirements. The project team should compare the current Type S product data with the roof assembly and applicable energy-code requirements. If thermal performance is a major concern, it may be useful to compare other Bilco models as well.
Installation Planning
Installation should follow Bilco’s instructions and the construction documents. A qualified contractor typically coordinates the opening, structural support, hatch placement, attachment, and roofing work. The hatch should be installed square and level on a properly prepared curb or support, with the cover able to open and close without interference.
Before work begins, the project team should confirm the hatch orientation, opening direction, access equipment location, and clearance around the cover. Nearby piping, ducts, mechanical equipment, parapets, and other roof features can obstruct use. Inside the building, the ladder or stair must align with the opening and provide a safe transition to the roof.
Installation planning should also account for temporary protection. An open roof opening presents a fall hazard during construction, maintenance, and replacement. The contractor should establish appropriate safeguards while the hatch is open or removed, following applicable workplace rules and the project’s safety plan.
Safety, Access, and Applicable Rules
A roof hatch does not by itself make roof access safe. The complete access system includes the hatch, ladder or stair, landing area, roof-side working conditions, and any required fall-protection measures. The building owner and employer should establish procedures for authorized access, inspection, and safe operation.
In the United States, OSHA’s general-industry rules address fall protection around holes and openings. Under 29 CFR 1910.28, employers must protect workers from fall hazards in specified circumstances. Section 1910.29 includes requirements for guardrail systems and covers, including criteria for covers over holes. The applicable rule depends on the work setting and conditions; construction work is governed by separate OSHA provisions.
OSHA requirements should not be interpreted as a product approval or a substitute for site-specific safety planning. A hatch cover may need to meet applicable load and securing requirements when it serves as a cover, while the opening may require additional protection when exposed. The employer, designer, and contractor should determine which requirements apply and whether a guardrail, personal fall-arrest system, or other measure is needed.
For workers using a fixed ladder, the ladder must be evaluated under the applicable OSHA requirements and the project’s design standards. The ladder’s location, clearances, landing, and transition through the hatch affect usability. A hatch that is difficult to reach or operate can encourage unsafe practices, so access should be designed as a complete system rather than as an isolated product choice.
Maintenance and Inspection
Routine inspection helps identify problems before they interfere with access or allow water intrusion. The building’s maintenance plan should reflect the manufacturer’s instructions, roof conditions, frequency of use, and exposure to weather or corrosive environments.
During an inspection, authorized personnel can check for visible corrosion, loose or damaged fasteners, worn seals, debris, and signs of water entry. They should also confirm that the cover opens and closes smoothly, the hold-open mechanism functions as intended, and hardware is secure. Any maintenance should follow the manufacturer’s instructions; improvised repairs or unapproved modifications can compromise operation.
Roofing work can affect the hatch even when the hatch itself is not being replaced. After roof repairs or resurfacing, the curb flashing and adjacent membrane should be checked. If a hatch is damaged, difficult to operate, or no longer compatible with the roof assembly, the owner should consult a qualified contractor and obtain the appropriate replacement or repair documentation.
How to Compare the Type S With Other Options
When comparing the Bilco Type S with other roof hatches, evaluate the complete specification rather than the product name alone. Material, insulation, dimensions, curb design, hardware, finish, operating method, and available safety accessories may differ across models. The right comparison depends on the building’s exposure, roof type, access frequency, security needs, and design requirements.
Steel may be a suitable choice for many projects, but the expected environment should be considered. Coastal air, industrial pollutants, persistent moisture, and chemical exposure can increase corrosion concerns. The specified material and finish should match the exposure, and the owner should understand the maintenance implications. Where corrosion resistance or thermal characteristics are priorities, compare current alternatives using their published product data.
Price should be evaluated alongside the full installed cost. The hatch itself is only one part of the project; framing, roofing work, flashing, access equipment, safety provisions, and maintenance all contribute. A lower purchase price may not represent the best value if the unit does not fit the opening or requires changes to the roof design.
Buying and Specification Checklist
Before purchasing a Bilco Type S roof hatch, request current product literature and a project-specific submittal. Confirm the model designation and every selected option in writing. A distributor or manufacturer representative can help verify availability, but the design professional remains responsible for matching the product to the building documents and applicable codes.
- Verify the exact model and current dimensional drawings.
- Confirm rough-opening and clear-opening dimensions.
- Specify curb height, finish, insulation, seals, and hardware as required.
- Check roof material, roof thickness, drainage, and flashing details.
- Coordinate the hatch with the ladder or stair, landing, and overhead clearance.
- Review security, safety, and operating requirements for the site.
- Confirm lead time, shipping dimensions, handling, warranty terms, and maintenance instructions.
- Retain the approved submittal and installation documentation for the building’s records.
Useful reference material includes Bilco’s official roof-hatch product information and installation documents, along with OSHA’s standards for fall protection and hole covers. Product specifications can change, so the current manufacturer documentation for the exact Type S configuration should govern ordering and installation.
Frequently Asked Questions
Is Bilco Type S a specific size?
No. Type S refers to a product line with configurations that may vary. The exact available dimensions and options should be confirmed in current Bilco literature or a project-specific submittal.
Can a Type S hatch be installed on any roof?
Not automatically. Compatibility depends on the roof assembly, opening, structural support, curb and flashing details, and the hatch’s specified configuration. A qualified design professional or contractor should verify the installation details.
Does a roof hatch eliminate the need for fall protection?
No. Safe access and fall protection depend on the conditions and applicable regulations. Employers must assess the opening and work activity under the relevant OSHA standards and provide required safeguards.
Where can buyers find accurate product dimensions?
Use the current Bilco Type S product data and dimensional drawings for the exact model and options. Confirm dimensions with the manufacturer or authorized distributor before the roof opening is framed or the hatch is ordered.
Reference resources: Bilco official product information; OSHA 29 CFR 1910.28, Duty to Have Fall Protection; OSHA 29 CFR 1910.29, Fall Protection Systems Criteria and Practices.