Bilco S-20 vs S-50TB Roof Hatch: Which to Buy, Plus Bil-Guard Rails

Logistics Lighting distributes Bilco roof hatches along with the railing and ladder post that complete each access point. The two Bilco hatches we list are both Type S ladder access hatches with a 36 x 30 inch opening. The S-20 is galvanized steel with 1 inch of insulation. The S-50TB is aluminum, thermally broken, with 3 inches of polyisocyanurate. Each one takes its own Bil-Guard 2.0 rail, the RL2-S or the RL2-STB, and either works with the LU-1 Ladder Up safety post.

S-20 vs S-50TB at a glance

	S-20	S-50TB
Opening	36 x 30 inches (3 ft 0 in x 2 ft 6 in), hinged on the 30 inch side	36 x 30 inches (3 ft 0 in x 2 ft 6 in), hinged on the 30 inch side
Cover and curb	14 gauge galvanized steel, 22 gauge steel cover liner	11 gauge aluminum, 18 gauge aluminum cover liner
Insulation	1 inch fiberglass in the cover, 1 inch rigid fiberboard on the curb	3 inch polyisocyanurate in cover and curb, R-20.3
Thermally broken	No	Yes, cover and curb
Curb	12 inches high, 3-1/2 inch flange	12 inches high, 5-1/2 inch flange
Overall size on the drawing	3 ft 1 in x 3 ft 7 in	3 ft 5 in x 3 ft 11 in
Factory finish	Red oxide primer	Mill finish aluminum
Live load	40 psf, maximum deflection 1/150 of the span	40 psf, maximum deflection 1/150 of the span
Wind and design pressure	Maximum design pressure of plus or minus 100 psf, design factor of 2	20 psf wind uplift
Miami-Dade and Florida	NOA 19-1029.10 and Florida approval FL15110 on the drawing	Not covered; the drawing note says S-20 and S-50 only

Both hatches have fully welded corners, pintle hinges (Type 316 stainless on the S-50TB), a slam latch with inside and outside handles and padlock hasps, an automatic hold-open arm with a red vinyl grip, and Bilco's Bil-Clip flashing tabs on the integral capflashing. Hardware is zinc plated and chromate sealed, with Type 316 stainless steel available for corrosive environments. Bilco's specifications give both hatches a five year warranty from the date of purchase.

Choose the S-20 when

You need a steel hatch, or the project requires Miami-Dade or Florida product approval, or the space below is not conditioned. The S-20 ships in red oxide primer. Bilco recommends an alkyd base enamel finish coat, in the color you want, after installation.

Choose the S-50TB when

The hatch sits over heated or cooled space. Bilco builds the S-50TB cover and curb with a thermal break to minimize heat transfer and resist condensation, and its insulation is R-20.3 compared with 1 inch of fiberglass and fiberboard in the S-20. The aluminum ships in mill finish.

Why the rails are not interchangeable

The S-50TB curb is larger overall than the S-20, and Bilco draws each Bil-Guard 2.0 rail for a specific capflashing. The RL2-S drawing is for a single leaf hatch with the standard 1 inch capflashing. The RL2-STB drawing is for a thermally broken hatch with the standard 3 inch capflashing. The two frames are different sizes overall.

	RL2-S	RL2-STB
Fits	S-20 (36 x 30, 1 inch capflashing)	S-50TB (36 x 30 thermally broken, 3 inch capflashing)
Overall rail size	3 ft 11-3/8 in x 3 ft 9-3/4 in	4 ft 3-3/8 in x 4 ft 1-13/16 in

Everything else is the same on both. The rails are 1-1/4 inch schedule 40 pipe in 6061-T6 aluminum, and the post supports and corner brackets are aluminum. The self-closing gate uses stainless steel spring hinges and a cast aluminum latch with a stainless steel pin, and all fasteners are stainless steel. The finish is safety yellow powder coat, RAL 1018. The top rail is set 42 inches above the roof surface, and our listings place the gate on the 30 inch side. The rail attaches to the capflashing and does not penetrate the curb. Bilco curbs come pre-punched for the mounting brackets, and Bilco says the system can be installed in less than an hour.

The Bil-Guard 2.0 also fits other brands of roof hatch that have capflashing. For those, Bilco needs both the hatch opening and the outside curb dimensions to size the rail.

The OSHA rules behind the rail

OSHA 1910.29(b)(13) requires a guardrail around an access hole to have a self-closing gate that swings away from the hole, or an offset opening. 1910.29(b)(1) puts the top rail at 42 inches, plus or minus 3 inches. The Bil-Guard specification says the system satisfies 1910.29 and meets OSHA strength requirements with a safety factor of two.

The LU-1 Ladder Up safety post

The LU-1 is the steel, yellow finish model of Bilco's LadderUP safety post, which comes fully assembled and mounts to the top two rungs of the fixed ladder under the hatch. It extends to 42 inches above the landing and retracts to 5 ft 1-3/8 in overall.

• The adjustable mounting fits rung spacing up to about 14 inches center to center.
• The clamp brackets reverse to fit rungs from 3/4 to 1-1/4 inches with the 2 inch stainless steel bolts furnished. Larger rungs need longer bolts.
• Mount it on the rear of the ladder with the clamp brackets on the climbing side. On hollow round rungs, insert solid round bar into the top two rungs first.
• Bilco recommends two people for installation. The pull-up loop is for raising the post only and is not for attaching a harness lanyard.

OSHA 1910.23(d) asks for ladder side rails on through ladders and grab bars to extend 42 inches above the landing.

Installation notes for both hatches

• Over a ladder, a Type S hatch with its 70 degree opening cover goes hinge side opposite the ladder, at the climber's back. OSHA 1910.23(d)(9) requires a counterbalanced hatch to open at least 70 degrees.
• The cover is spring loaded. Leave the steel strapping on until the hatch is ready to install and sitting level.
• Shim under the flange if needed so the frame is not twisted, then fasten through the 7/16 inch anchor holes.
• For single ply roofing, tuck the membrane under the capflashing and bend the Bil-Clip tabs in. For built-up roofing, do not bend the tabs.

FAQ

Will an RL2-S fit an S-50TB?

Order the RL2-STB instead. Bilco draws it for the thermally broken hatch with 3 inch capflashing, and its frame is larger than the RL2-S.

Which hatch is Miami-Dade approved?

The S-20 drawing lists NOA 19-1029.10 for the S-20 and S-50 only. The S-50TB is not on that note.

Do I have to paint the S-20?

Bilco recommends it. The steel ships in red oxide primer, and Bilco's maintenance instructions call for an enamel finish coat after installation.

Next steps

Every Bilco item we carry is on the Bilco brand page, and the drawings are on the roof hatch and ladder spec sheets page. To get a hatch, Bil-Guard rail and LU-1 quoted as a set, send the hatch type, quantity and ladder rung size through the ladder and hatch request for quote page.