We carry two Babcock Davis roof hatches for the standard 36 x 30 inch ladder opening. The BG3630 is the Personnel hatch in red oxide powder coated steel. The BRHTA36x30S1T is the ThermalMAX hatch in aluminum, with a thermal break and 3 inches of insulation. Each one has its own safety railing: the SRCAY36X30FG for the standard hatch and the SRBAY36X30FG for ThermalMAX. The BSPY ladder safety post completes either setup.
BG3630 vs BRHTA36x30S1T
| BG3630 (Personnel) | BRHTA36x30S1T (ThermalMAX) | |
|---|---|---|
| Size | 36 x 30 inches inside the curb | 36 x 30 inches inside the curb |
| Cover | 14 gauge galvanneal steel, red oxide powder coat | 11 gauge aluminum, mill finish |
| Curb | Single wall with EZ tab counterflashing and mounting flange | Thermally broken single wall with railing ready EZ tab counterflashing and mounting flange |
| Insulation | 1 inch polyiso (R-6) in the curb, 1 inch polystyrene (R-4) in the cover | 3 inch foil faced polyiso in curb and cover, R-20.3 |
| Live load | 40 psf, maximum deflection 1/150 of the span | 40 psf, maximum deflection 1/150 of the span |
| Operation | Gas spring with damper | Gas spring with integrated damper |
| Latch | Zinc plated slam latch, inside and outside handles, padlock hasps | Same, rated for 20 psf wind uplift |
| Approvals and testing | Miami-Dade County and Florida product approved; tested to TAS 201-94 (Class IV impact), TAS 202-94 and TAS 203-94 | None listed on the data sheet |
| Weight | Not on the posted documents | 115 pounds |
Both hatches have a pintle hinge with a stainless steel pin, an automatic hold-open arm with a red grip release, and a safety yellow interior pull-down handle. Babcock Davis measures width from hinge to latch and length along the hinged side, so on a 36 x 30 hatch the hinge runs along the 30 inch side. The roof rough opening is the same as the hatch size.
When the ThermalMAX is worth it
Babcock Davis designed the ThermalMAX with a thermal break to stop heat and cold from moving through the hatch, and rates it at R-20.3 against R-6 in the Personnel curb. Choose it over conditioned space where the hatch would otherwise be a weak spot in the roof insulation. The ThermalMAX drawing shows a clear opening of 28-1/2 x 29-3/4 inches and a cover that opens to 79 degrees. OSHA 1910.23(d)(9) requires a counterbalanced hatch over a fixed ladder to open at least 70 degrees.
When the BG3630 fits better
The Personnel data sheet lists Miami-Dade County and Florida product approval and notes that the stainless steel version is not approved. The installation manual cites Miami-Dade NOA 21-1201.02 and gives separate anchoring schedules for wood, steel and concrete curbs on Miami-Dade installations. If the project needs that approval, start with the BG3630.
Match the railing to the hatch
The Babcock Davis safety railing data sheet lists two families. SRCA models are the standard models and SRBA models are the ThermalMAX models. The SRBAY36X30FG drawing is titled for a 36 x 30 thermally broken hatch. So the SRCAY36X30FG goes with the BG3630, and the SRBAY36X30FG goes with the BRHTA36x30S1T. Both have a front exit gate and a safety yellow finish.
- Rails and posts are 1-1/4 inch ID (1.66 inch OD) schedule 40 pipe in 6061-T6 aluminum, with cast fittings held by set screws.
- The brackets mount to the hatch counterflashing without penetrating the membrane or the curb, using 3/16 inch zinc-plated steel brackets, a nut backing plate and 3/8-16 x 3/4 inch hex bolts.
- Rails are cut to size at the factory, so no field cutting is needed. The installed height is 42 inches.
- The self-closing gate is 1-1/4 inch aluminum pipe with a coil spring.
The installation manual calls for 1/2 inch holes in the counterflashing sealed with roofer's caulk, brackets torqued to 29 ft-lb, and the mid rail set 21 inches center to center below the top rail. Railing packages also include a chain, which is not used when the gate is installed. The data sheet calls the chain closure option not OSHA compliant. OSHA 1910.29(b)(13) requires the opening in a guardrail around an access hole to have a self-closing gate or an offset.
The BSPY ladder safety post
The BSPY is a spring-assisted, telescoping steel post in yellow powder coat. It mounts to the top two rungs of a fixed ladder and extends 42 inches above the landing. It is made from 1-1/2 x 1-1/2 x 1/8 inch square tubing, with a stainless steel constant force spring, Type 316 stainless hardware and a pull-up loop at the top. The locking bracket engages automatically when the post is fully raised. To lower it, lift the release handle.
- The adjustable mounting channel fits rung spacing from 10 to 12 inches. The clamp brackets reverse to fit rungs from 3/4 to 1-1/4 inches with the standard 2 inch bolts.
- Mount it on the wall side of the ladder. Reinforce hollow rungs with solid round bar first.
- The cut sheet lists a 200 pound design load and shows the 7 inch minimum clearance behind the ladder that OSHA 1910.23(d)(2) requires.
Reading the part numbers
| Part | What the Babcock Davis tables show |
|---|---|
| BG3630 / BW3630 / BA3630 | The same 36 x 30 Personnel hatch in red steel, white steel or aluminum |
| SRCAY vs SRCA | The same railing in safety yellow or mill finish. SRBAY and SRBA are the ThermalMAX versions |
| BSPY / BSPG / BSPA / BSPS | Safety post in yellow powder coated steel, hot dip galvanized steel, mill aluminum or 304 stainless steel mill finish |
The roof hatch and railing specifications both call for a five year manufacturer's warranty.
FAQ
Which railing fits the ThermalMAX hatch?
The SRBAY36X30FG. Babcock Davis lists SRBA railings as its ThermalMAX models, separate from the SRCA railings for standard hatches.
Can I use the chain instead of the gate?
Babcock Davis calls the chain closure not OSHA compliant, and OSHA 1910.29(b)(13) calls for a self-closing gate or an offset at an access opening. Order the gate.
Do these hatches work on a sloped roof?
Yes, up to a 7:12 pitch, with the hinged side running parallel to the slope.
Next steps
All five products are on our Babcock Davis brand page, and hatch drawings from every manufacturer we carry are on the roof hatch and ladder spec sheets page. For the rules behind hatch railings, see OSHA fall protection for skylights. To have a hatch, railing and post quoted together, send the opening size, the hatch series and your ladder rung size through the ladder and hatch request for quote page.
Product data on this page comes from the manufacturer's published data sheets, drawings and installation instructions, which are posted on each product page. Code references are to the current OSHA text. Always confirm requirements with the authority having jurisdiction for your project.
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