DIY floating stairs
How hard would it be to make a modern staircase to embellish your new build house? Not too hard is the answer, as long as you design it to be DIYable from the outset.
This modern staircase is based on two 100×50 HRS hollow steel box beams with chunky wooden treads supported on 40x40x6 bright mild steel angle iron support bars welded onto the beams.
The angle iron bars are completely hidden inside the treads which appear to float without any means of support. If you are handy with a router and a welder (MIG is easy) then the construction should be quite straightforward.
A slot under the front of each tread is for LED strip lights mounted in aluminium channels with diffuser covers. Leave a little space around them for cooling and rout out a channel under the angle iron for the wires. You also need a hole through the angle iron and the box section for the wires to pass into the box section, preferably with a rubber grommet. The stairs lit with any colour you chose will be absolutely stunning.
A bought in staircase like this would cost at least £5,000 – £10,000 so you can afford to sub out some of the work to make it easier and buy any tools you need. The routing work is very repetitious and it would be worth getting a local CNC router on the case; there is only about an hour of machining time and accuracy will be pefect. Get the angle iron brackets cut to length too. There will be many chamfered holes to make so I’d say a pillar drill will be essential.
Tradition has it that a comfort stair was 7” x 11” for rise and going. Rounding up slightly that’s 180 x 280mm. B.S. regulations for rise is 150 -220mm and 220-300mm for going G. The ratio of rise to going gives an important angle which here would be around 33 degrees and must not exceed 42 degrees. You’ll need this angle to saw off the ends of the beams and to mount the angle iron brackets.
The distance H between your two floor levels will set the rise. Find which whole number divides into H to give a rise R near to 180mm or what you prefer. That whole number is one more than the number of treads.
Tread thickness T. B.S. regs state that a 100mm ball must not pass between stairs or guards so if we say that the open gap between the treads will be 98mm then T = R – 98 or more.
Going overlap. B.S. regs state that the overlap on open stairs must exceed 16mm but too much spoils the design, as you will see when you draw yours. So tread width W = G + 20 will do for a start.
So the treads will be something like 300 x 80 in section. As for length just bear in mind that stairs over a metre wide must have hand rails on both sides. I think 85cm looks about right.
Length of box beams L. To make life easy you could set the top of the box beam level with the top of the top tread, so; The base of our triangle is (no of treads -1) x G / R and then just use Pythagoras to get the longest length of box…. or just draw it and see what you get.
Make a note of all your numbers then make a drawing of the side elevation to scale. Sketchup is perfect for this and is free and easy to use. Note the intersection of the top of the angle iron, the beam and the back of the tread. N.B. Sketchup can repeat copies easily so draw and colour just one tread then copy it upwards by the rise and then across by multiples of the going. You’ll need a jig to position the angle supports easily – draw this too to see how it will work.
The safest way to make the stairs is to bolt the two steel box sections firmly in place using the top and bottom cross members. With a sliding jig, position the angle irons, measuring the height of each one from the floor. Tack the angles on and then take the whole thing down to weld it properly. To prevent any distortion I’d weld on a few cross struts then grind them off afterwards. If you can cope with the weight it will be easier to turn it all upside down to screw on the treads before remounting it. Fit and test the lights too.
If you make these stairs I’d be very glad to hear about it and to put your photo with this article.
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