I am sorry, but I don't have enough information to answer your question about guardrail heights in the NYC DOB code. The documents provided do not contain specific regulations or codes related to New York City's Department of Buildings (DOB). However, I can provide general information on guardrail requirements from other jurisdictions.

Generally, guardrails are required to prevent falls from elevated surfaces. Here are some common requirements for guardrail systems:

• Height: Guardrails typically need to be between 36 inches (0.9 m) and 45 inches (1.2 m) above the working surface 4, 8. Some regulations specify a height of not less than 900 mm or more than 1.07 m from the floor level [1].
• Midrails: Intermediate members, such as midrails, screens, or mesh, should be installed between the top edge of the guardrail and the working surface 4, 8. When midrails are used, they should be placed approximately midway between the top edge of the guardrail and the platform surface 4, 11.
• Strength: Guardrail systems must be capable of withstanding a certain amount of force. For example, a toprail should be able to withstand a force of at least 200 pounds (890 N) applied in any direction [2].
• Materials: Guardrails can be made of various materials, such as wood, metal pipe, angle iron, or wire rope [1]. Wood components should be construction grade lumber or other materials of equal or greater strength [3].

To find the specific guardrail requirements for NYC, you should consult the official NYC DOB codes and regulations or contact the DOB directly.