the stairwell length
calculate the stairwell opening. See figure 44B. Stairwell length =
Unit Run divided by
Unit Rise times the sum of the
headroom and floor frame plus 75 mm.
Calculate the unit rise first. The total rise is 2100 mm. The desired
rise is 180 mm. Calculate the
rise. 2100 divide by 180 = 11.67. It is rounded off to 12.
by 12 = 175, the unit rise. 175 mm is an acceptable rise
falls between the building codes upper and lower limits of 200 mm and
125 mm. The unit rise will be 175 mm.
Calculate the unit run. 175 + 175 = 350. 550 - 350 =
200. 700 - 350 = 350. The unit run limits in the building
are 355 and
210. Select a unit run between (and including) 210 and 350. The unit
run will be 250 mm.
The headroom is
2000 mm. According to the1998 B.C. Building Code Section 18.104.22.168. Page
dwelling units must not be less than 1.95 metres and 2.05 metres in
The floor frame thickness is the sum the floor
vertical measure of 255 mm and the finish and subflooring measure of 30
mm. The floor frame thickness is 285 mm.
Stairwell Length = 250 mm divided by 175 mm times
285 mm) + 75 mm = 3339 mm.
44B The Parts Of A Stair
Calculate The Unit
Unit Run Of Stairs.
Layout A Stringer When The Floor Frame Is The Top Step.
Layout A Stringer When The Top Step Is Attached To The Floor Frame.
Layout The Rise & Run Along The Stringer.
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images and text are copyright Ronald Hunter 2005 to 2011