I'm figuring out exactly what design of staircase I want to use in a chapel conversion.
The fixed parameters: Floor space footprint available 3030 by 3890 mm Vertcal height 3900mm Adjacent walls only on 3030mm edges (3890mm edges are limited by a internal balcony), so no supporting walls apart from at the head of the stairs.
Think of it as a freestanding staircase, within the specified cube.
The staircase will be central in a 11450 by 9090mm building, internally. The staircase will be wooden - and custom made - by me.
It must fit within that cube, and the top step must meet with the
3030mm edge (ideally centrally, and any reasonable width).
The bottom step can face any direction within the footprint, but ideally the opposite 3030mm edge.
Buidling regs limit the pitch to 42 degrees max and the rising and going per tread (in mm) to:
Rise: 155-220, Going 245-260 or Rise 165-200, Going 223-300
The rest I'm open to. A single straight run won't fit. Spirals are a PITA in my opinion. A helix (with central void) is a maybe, particularly in a squared off format.
I know a simple u-shaped stair would work. I'm looking for something with a bit of flair - I welcome your suggestions!
(and I know this may be hard to visualise - I'll keep coming back to answer questions).
You could have a straight flight in the middle then a wide landing the full width and then 2 flights either side leading back. It would look like a smaller version of the type you get in cruise liners or large country houses.
It could be done either way round, with the single flight being at the top or bottom.
I managed to both meet building regs and cram a similar staircase in a very small foot print by using the spiral.
The 42 degree limit applies only to a straight staircase...a spiral one is obviously far steeper at the center and somewhat less outside.
I just measured mine ...2.2 meters between floors and 1.5 meters by two meters foot print. actual treads are 800 mm wide...its 180 degrees turn over the total rise..rise is 200mm per step and the straight going is
240 or 250mm...
Its done as three sections..a short straight rise, of two straight steps, leading to three angled steps, turning 90 degrees.. a straight step, three more angled steps and then three more rises onto the upper storey. 11 rises in all for the 2.2m
I am certain you could fit something like that in.
at 200mm rise you need 15 steps ..well rise will be a tad more..202mm..
at 250 going you can easily fit half the steps into 2 meters of staircase..then add an 800mm wide 'landing' halfway up, and the last half run going backwards from there and you can fit the whole thing into about 1.8 x 2.4 meters.
You can offset that within your footprint to get the top step central.
Its not as compact as mine, but the use of a 'landing' halfway up will make the construction a LOT easier.
More of an aside than a direct answer to your q's - I built my staircase around 10 years ago using instructions in WB McKay "Building Construction". McKay shows you how to make the real traditional McCoy. You can adapt to suit yourself. Look out for timber merchants with standard staircases in stock, it isn't hard to improve on those, especially with McKay as a guide.
References are: Staircase basics in: Vol1 & 2 (combined ed) chapter 4 pp123-125 [3rd metric edition 1971] & everything you need to know to make a staircase twirl into the sky in vol 3 chapter 2 pp 97-117 [5th metric ed 1973]. I believe these are long out of print but you may find copies in a good library or try abebooks.uk. Doubt if there is much difference between editions on the staircase sections.
The sort of staircase it sounds as if you are looking for is covered in vol 3 & lots of options and variants are shown.
A problem I found at the time was obtaining timber in suitable sizes. It may be easier to track down stockists now the www is available. I used a router as a biscuit jointer to make up wider strings.
Another observation: I was puzzled when planning the stairs by the going+riser rule (which you quote) in the building regs, and of which the regs make such heavy weather. In fact this is a rule of thumb which just made sure in pre-computer days that the going and the riser will meet near-enough at a right angle. (It is Pythagoras in wolf's clothing). Ignore the rule, decide on the angle you want & work from there.
Incidentally there's no rule which says the going has to be level front-to-back, but I discovered a public staircase which wasn't. Climbing it was quite unnerving, and it was only slightly out of kilter. Even a 1 deg slope is perhaps too much.
I set out all the calculations on an Excel spreadsheet. Saved an enormous amount of time during planning and building. I could juggle the numbers and see what effect a change had on the whole and how it affected timber sizes. The sheet helped a lot when marking out the timber for cutting and routiing as it did the trig calcs & presented all the finished correct lengths
At the time I looked around at a lot of stairs & came to the conclusion that stairs at a low pitch (long going+short riser) make for quite a hard tramp up and a difficult descent. Risers around 165-185mm seem to be ideal. Higher than that and it is more of a climb for shorter people. IIRC the Going needs to accommodate around 2/3 the length of an average male shoe - around 265(??)mm. It seems that in N America building codes permit steeper staircase than here, so be careful if you reference an american textbook.
Other factor I observed about stairs is that you go up a staircase in a diffrerent way to going down it. There's differences between how men & women climb stairs too. . It put a new gloss on why women like high heeled shoes. Observe carefully
I've been reading all your replies with interest. At the moment, I'm coming down towards a u-shaped (switchback) stair - actually with two lower risers either side of the central riser (so more of a double-u).
This is still a squeeze to get inside the footprint, because of the height required (i.e. taking up nearly all of the long side of the footprint - taking up all the width is ok). And the stair starts from the same side it finishes - and I'd prefer that it started on the opposite side of the footprint to which it finishes. But the half-turn landing is in a good position to face the front doors, I like that bit.
So I'm still considering a triple switchback or even a helix (similar to a spiral, but going around a square central void). But possibly more work than I'd want to take on.
Incidentally, why are ready-made staircases so expensive? Even simple, straight, 2.7m rises in pine seem to be very expensive compared to what the materials would cost in planed timber. In these days of CNC machined timber, I can't believe the manufacture cost is multiples of the raw material cost - they must still be charging "hand-made" prices.
If your footprint is small - mine was - be very careful about the angle you choose. The going+riser rule in the bldg regs is deceptive. Normal cautious engineering rule of thumb would be to select middle values for the going & rising from the table in the absence of further info. Unfortunately that gives a very steep staircase & the high rise in your case will make for even more difficult stairs to climb. If you possibly can, choose a lower angle.
Looking back, a larger footprint (which would have meant extra brick & building work plus some loss of living space) would have produced a far better job.
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