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floor transition height

floor transition height

New postby bigdog on Wed Feb 16, 2022 4:18 pm

Hi Jerry

What is the maximum height difference allowed when transitioning from one room to another or even a height difference in the same room? Old house with some original wooden floors and some tiled.
Thanks in advance

David
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Re: floor transition height

New postby Jerry Peck - Codeman on Wed Feb 16, 2022 10:47 pm

David, that depends on how old the house is and the code which was applicable at the time of construction.

That 'one step' (change in elevation) is a single riser "stair" with a landing at top and bottom (the floors are the "landings").

Going back to around 2000 and newer will likely be about a 7-3/4" maximum rise height.

Going back to 1970s or 1980s and sone codes allowed 8" riser heights, some even 9" as I recall.

Going back to the 1950a or 1960s and 9" or so was common.

The old standard in many codes until around the late 1990s (around the time SBCCI became ICC with other model codes) was the same one used back to the 1960s, maybe earlier: the sum of two risers and one run (one tread) equals between 24 and 25. That would seem to preclude 9" risers ... but only when the code stated a minimum tread depth (most did, some did not). Those that did typically stated minimum 9" tread depth, which calculated out to two 8" risers for the " 25 " number.
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Re: floor transition height

New postby Jerry Peck - Codeman on Thu Feb 17, 2022 1:26 pm

David, how high was that riser (difference in elevation between floors)?
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Re: floor transition height

New postby bigdog on Tue Feb 22, 2022 9:04 am

There is no step.

This is an old house 1925.

They added plywood to the kitchen (tile) and a bedroom (who knows why) both of which have doors to the living room which is the original Dade county pine.
There is a beveled threshold between the bedroom and living room. No threshold between the kitchen and living room. Both are over 3/4" high and trip hazards in my opinion.
I remember something in the code about bevels being required but always thought 3/4" was max allowable height difference.
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Re: floor transition height

New postby Jerry Peck - Codeman on Wed Feb 23, 2022 9:02 pm

Ah, now I understand what you are asking.

If ... that big IF ... the building was subject to the Accessibility Code, then there are specific requirements which apply to changes in elevation such as you describe, as well as all other changes in elevation, but in a residence ... none apply.

If under the Accessibility Code, a 1/4" maximum vertical change in level (elevation) is allowed. A change in level greater than 1/4" requires a slope beginning at that 1/4" height point with the slope being 1/2 (i.e., one unit vertical in two units horizonal, or 1/4" vertical rise in 1/2" horizontal run) for changes up to 1/2".

- 303.3Beveled.
- - Changes in level between 1/4 inch (6.4 mm) high minimum and 1/2 inch (13 mm) high maximum shall be beveled with a slope not steeper than 1:2 ,,,

For changes in level greater than 1/2" a ramp is required ...

- 303.4 Ramps.
- - Changes in level greater than 1/2 inch (13 mm) high shall be ramped, and shall comply with 405 or 406.

Also keep this in mind:

"This is an old house 1925."

When was the plywood put down? When that work was done, that is the code which applies, not a 1925 code for the original construction, but the code in effect at the time the work was done.
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