When Can a Parapet Be Used as a Guardrail?

Work through these five checks at every stretch of parapet where people work. The answer can change from one side of the roof to the other.

1. Is anyone working near the edge? If people service equipment, inspect the roof, or clear drains, treat the edge as a fall exposure and keep going. Under OSHA general industry rules, fall protection is required at 4 feet above a lower level (29 CFR 1910.28(b)(1)); construction work triggers at 6 feet (29 CFR 1926.501(b)(1)).
2. Is the parapet tall enough? Measure from the surface workers stand on to the top of the parapet. If the top is not within 42 inches, plus or minus 3 inches, the parapet is not the guardrail. Go to the options below.
3. Is it strong enough? The top has to withstand 200 pounds of outward or downward force. Old masonry, loose coping, framed walls and metal panel parapets may not. If nobody has verified it, do not count it.
4. Is it continuous? Low sections, scuppers, gaps, and spots where equipment or a step raises the walking surface near the parapet all reduce the protection at that spot. Each one needs its own answer.
5. Yes to all four? The parapet can serve as the guardrail at that location. Write down the measurement and the check, and repeat both after any re-roofing.

The height that counts runs from the surface a worker stands on to the top of the parapet. It is not measured from the roof deck, the structural slab, or the ground outside.

That surface changes over the life of a building. A new roof, tapered insulation, pavers, or walkway pads raise it, and every inch they add comes off the parapet. A parapet that measured tall enough ten years ago may not today. We measure at each change in roof level and around each piece of equipment, and we measure twice, because the gap between passing and failing is often a few inches.

A parapet is built to finish a building and hold back weather. It is not automatically built to stop a person. To count as a guardrail it also has to withstand 200 pounds of outward or downward force at the top (29 CFR 1910.29(b)).

OSHA also requires a midrail, or an equivalent intermediate member such as a screen or mesh, on a guardrail system when there is not a wall or parapet at least 21 inches (53 cm) high. Midrails, when used, sit midway between the top edge and the walking-working surface. The same midrail rule appears in general industry (29 CFR 1910.29(b)(2)) and in construction (29 CFR 1926.502(b)(2)). Midrails and other intermediate members must withstand a force of at least 150 pounds in any downward or outward direction (29 CFR 1910.29(b)(5) general industry; 29 CFR 1926.502(b)(5) construction). Top rails and midrails must be at least 0.25 inches (0.6 cm) in diameter or thickness (29 CFR 1910.29(b)(9); 29 CFR 1926.502(b)(9)). A parapet that already meets the 42-inch, plus or minus 3 inches, top-edge height can serve as the guardrail without a separate midrail. If a rail is added to a parapet shorter than 21 inches, that new guardrail system needs the midrail or equivalent. A parapet that is at least 21 inches high may itself count as that intermediate member under those paragraphs.

What is behind the finish decides that. Solid reinforced concrete is different from hollow block, single-wythe brick, a wood-framed wall, or a metal panel on light framing. Mortar, coping fasteners and old repairs all age. We look at the building drawings, look behind the coping where we can, and have the design reviewed by a licensed engineer. We do not assume a wall is strong because it looks solid.

When the parapet falls short, there are three ways to protect the edge. Tritech engineers all three, so the recommendation follows your parapet, your roof membrane and its warranty, not a product line.

• Anchored parapet guardrail. The rail is anchored into sound parapet structure, top or side mounted, with the load path checked and the coping kept watertight.
• Clamp-on parapet guardrail. Where the parapet width, coping and condition allow, the rail clamps to the parapet without drilling.
• Freestanding guardrail set back from the edge. When the wall cannot carry the load, a non-penetrating roof guardrail on weighted bases protects the edge without relying on the parapet.

How we choose among those three options is in anchored vs non-penetrating guardrail.

ViewView

Click any photo to enlarge

See every option in one place on our roof guardrail systems page, or go straight to the parapet guardrail system page.

Most parapet questions get answered on the roof, not on the phone. Here is what we do on every job, large or small.

1. We walk the roof with your team. The people who use the roof know where they go. We follow the routes they actually take.
2. We measure twice. Parapet height from the walking surface at every level change, plus wall width, coping, and condition.
3. We check the structure. Building drawings, what we can see behind the coping, and an engineer’s review.
4. You review the design. You get PE-stamped drawings and a clear scope before anything is fabricated.
5. We install, train, and certify. Our own crew installs, your people are shown how the system works, and you get the certification and drawings for your file.
6. We come back. Annual inspection and recertification, and a re-check after any re-roof.

Learn how our fall hazard assessment works, or see fall protection services from design to recertification.