Good Tread & Riser height for ladder/stairs

[Kenn]

I want to build an easy to walk stair or ladder to go from the rear deck to the roof of the saloon about 7 ft. Any experience/ideas on width, tread and riser heights. It can take up some space down the side of the house, I'll use the space under for lockers or hanging "stuff".

Thanks, Kenn

[Peerie Maa]

Yet again, F S Kinney's 8th edition of Skene's Elements of Yacht Design is your friend.

1) divide height into equal spaces of between 9" and 11". They MUST be equal.
2) the top step will be 9" wide, the next down projects forward 5" and overlaps by one, making a 6" tread. So on to the bottom.
Minimum width 15", but 18" is better as you can the sit on the top step.
Don't forget hand holds, as boats do move about.

[Thorne]

I'd be tempted to say that you should either match other stairs/ladders on the boat, or go for the standard riser/tread sizes used in new home/building construction. But I'm a small boat guy...

[Don Kurylko]

I just built a companionway ladder for my cutter and spaced the treads 12" apart, just like my aluminium step ladder. Worked just fine. Treads are 6" deep and 18" wide. Nothing fancy.

[Kenn]

I'm an old carpenter and had thought of just using standard housing code tread and raiser.
Didn't know if 18 or 24 inch wide was the way to go. Maybe 24 wide with the handlerail attached to each side, ending up with a net 20 to 18 inches clear space.
I'm going to walk around the marina in Apalach and Carrebelle to eyeball the trawler and sportfisherman.

Don thanks for the hands on response.

I would like to hear form someone who has a set they like. Remember mature adults will be using this.

Thanks again, Kenn

[Peerie Maa]

Ken,
If the climb is exactly 7' you can use seven equal 12" risers, but you said "about" seven foot. Divide the actual height into equal rises of no more than 12", but keep them equal. A sudden difference in rise is a trip hazard. So if your rise is any more than 7' use eight equal rises.

[mmd]

Peerie Maa has it about right; use his described method.

A couple of comments, though: the taller tread spacings (11" - 12") and narrow widths (15"- 17") are for spry young'n's; for those of us approaching senior citizen status, opt for lower and wider treads.

[Soundman67]

does this help?

http://www.osha.gov/Publications/osha3124.pdf

[Uncle Duke]

Ken,
If the climb is exactly 7' you can use seven equal 12" risers, but you said "about" seven foot. Divide the actual height into equal rises of no more than 12", but keep them equal. A sudden difference in rise is a trip hazard. So if your rise is any more than 7' use eight equal rises.
Small extension, if you don't mind: note that your total height should be measured to the highest point of the section of the roof where you'll be exiting, even if that point is not centered. Feet learn exactly how much to lift for each step (even a quarter inch can start a stumble) and it's safer to have the foot's "auto-lift" above where it will end up (so it drops a little on the last step onto the roof) than below (so the toe bangs against the roofline).
Just sayin'