Ladder safety - what is the maximum height of different ladders?

Please inform me regarding:

- What is the maximum height of:
1) a step ladder
2) a straight ladder
3) an extension ladder
4) a ladder used for scaffolding access

Please find attached. It's more than you requested.

Thank you,

Dear friends,

Regarding ladder safety, I find the discussion very informative. Can anyone explain why the 4:1 (4V to 1H) ratio is universally accepted as safe worldwide? There must be a specific reason that dictates why a safety professional cannot simply say, "keep the ladder that way."

Let's begin the investigation!

Regards,
Kesava Pillai

Dear Sir ,
We all forum member always waiting for your kind comments.
4:1(4V to 1H) ratio creats the angle (75-1/2 deg) which enable us to utilizes the ladder's strength and gives us optimum balance when climbing.
Regards,
Abhaygirish

Dear Mr. Sayeed,

Thank you for sharing a good presentation on Ladder Safety. Keep on sharing.

Dear Kesava Pillai Sir,

I was not aware of the answer to the question you raised. I then searched the internet and found the following: "If the base is moved out further, the stress on the side rails is more severe, and the wider angle may cause slippage."

I look forward to hearing your comments. Please continue sharing your expertise with us.

Dear sir,

Here is the answer. I hope it's correct.

Two reasons:

Mathematical: If you do the math regarding the side adjacent, the side tangent, and the hypotenuse, and consider the angular momentum of the dynamic loads involved on a ladder, you realize that the 4 to 1 ratio provides the best possible load distribution at ground and tangent with the greatest stability.

Empirical: If you have a human of average height stand straight with arms extended either to each side or to the front, the triangle described by the malleolus of the ankle, the shoulder hinge, and the knuckles of the finger describes a right triangle with the ratio of the side adjacent to the side tangent being 4 to 1.

Dear Abhay & Dipil,

Thanks for your inputs.

Waiting for expert commands. . .

Dear friends,

It is interesting to see many "attempts" around the questions. The specific question here is "what is the maximum height of:

1) step ladder
2) straight ladder
3) extension ladder
4) ladder used for scaffolding access?"

We find a lot of postings but none with a definite answer. Can anyone try to answer the question, please?

The PPT from Mr. Sayeed, the 27th one, needs correction. We have to digest the meaning of 4:1. The maximum height of the step ladder and extension ladder given as 20' and 44' also requires clarification. Kindly check!

Regards,
Kesava Pillai

Dear Mr. Sharma,

Thanking the gentleman for posting an informative PPT would be appropriate, which 99% of us would never have known; then treating it with disdain.

Jude

Dear HSE Officer JSK,

Your question:
What is the maximum height of:
1) a step ladder?
2) a straight ladder?
3) an extension ladder?

The answer is attached.

For 4) the ladder used for scaffolding access: the maximum height is 30 feet.

Regards,
Kesava Pillai

I saw a ladder safety book by OSHA that had an explanation regarding the 4:1 height to base ratio. From this book, I understand that this ratio is for keeping the ladder at a safe angle of 75 degrees to prevent accidental slips while climbing. This information is explained on page number 11 of the book, which also provides an explanation of how to achieve this ratio.

To achieve a 4:1 set-up angle, a non-self-supporting ladder should have a set-up angle of about 75 degrees — a 4:1 ratio of the ladder's working length to the set-back distance.

Here's how to achieve it: Stand at the base of the ladder with your toes touching the rails. Extend your arms straight out in front of you. If the tips of your fingers just touch the rung nearest your shoulder level, the angle of your ladder has a 4:1 ratio.