Steel staircase on the cheap

[Nelliekins]

OK so we have blown the budget for the house, primarily fixing the leak in the basement that we got thanks to Logix UK... ?

 

We need some stairs to go up from ground floor to first floor. We're looking at a quarter landing, with the landing outer edges against concrete ICF walls, so 3 corners of the landing can be fixed to concrete. However the inner corner of the quarter landing has no support. We can't put a newel post up from ground floor, because the stairs are directly over the stairwell to the basement. Here's a picture of the basement stairs:

 

 

We need to mirror this staircase, directly above it. 

 

I can't think of a solution with timber, so I am thinking outside the box. Could we weld some steel channel as the stringers and a frame for the quarter landing, then steel angle on each stringer as a support for the treads? We have a tame welder who will work for scotch (after he's finished!) and the steel channel only costs 100 quid...

 

Any thoughts anyone? This is the detail I am thinking of for lower flight to landing:

 

 

Or maybe this :

 

 

Then we would weld brackets like these for the treads to sit on :

 

 

They're made by Simpson Strong Tie, and specifically designed for stair treads, and cost about a fiver. 

 

Suggestions welcome! 

[Onoff]

 

I have a steel staircase construction book that may help you. You have a pm.

Edited April 6, 2019 by Onoff

[Russell griffiths]

Why use that bracket by Simpson when you could cut and weld some flat bar on, the Simpson one will not match the finish of the stringers. 

[CC45]

Angle iron?

[Russell griffiths]

The 150x10 flat would flex to much, must have some form of angle in it. 

Channel, angle, box, 

[Nelliekins]

5 hours ago, Russell griffiths said:

Why use that bracket by Simpson when you could cut and weld some flat bar on, the Simpson one will not match the finish of the stringers. 

 

Makes sense, and would probably be a lot cheaper too! 

 

4 hours ago, CC45 said:

Angle iron?

 

Yep, something like 200mm lengths of 50x50x5 would be perfect I would think. 

 

4 hours ago, Russell griffiths said:

The 150x10 flat would flex to much, must have some form of angle in it. 

Channel, angle, box, 

 

We would bolt a timber to the steel plate if for no other reason than to match the treads and risers (which will be timber). And the treads and risers would give us racking strength as well. Plus a point to build a handrail from... 

[Russell griffiths]

I think Pinterest is the place to look. 

[Ferdinand]

Why not start your newel post in the basement, and have it spanning 1.5 or 2 floors .. or run it right through to the ceiling?

Edited April 7, 2019 by Ferdinand

[Nelliekins]

On 07/04/2019 at 21:04, Ferdinand said:

Why not start your newel post in the basement, and have it spanning 1.5 or 2 floors .. or run it right through to the ceiling?

 

That's what we thought of first, but decided it wouldn't look great... Steel stairs would float which is (in our opinion) a much cleaner look, and wouldn't get in the way trying to get stuff down the stairs either! 

[Onoff]

Spiral stairs?

[Howard B]

Whichever option you go for you may need to ensure you have a double joist on the landing at the top of stairs to help support it.

 

How much headroom do you have down there?

 

Also if it helps check out mrstairs.com. They have a nice online staircase design tool which will help you get a good reference for your space, even if you do not order from them.

 

 

 

 

[Nelliekins]

On 09/04/2019 at 16:55, Onoff said:

Spiral stairs?

Not really suitable for the space because the opening has been designed for a lift shaft to go down the "spare" area in the opening. 

 

On 11/04/2019 at 09:39, Howard B said:

Whichever option you go for you may need to ensure you have a double joist on the landing at the top of stairs to help support it.

 

Aye - we already have a double posi-joist at the top of the stairs. 

 

On 11/04/2019 at 09:39, Howard B said:

How much headroom do you have down there?

 

It's 2.85m floor-to-floor. The upstairs floor build-up is 255mm posi-joist, 22mm structural deck, 50mm EPS and 18mm floating floor, so 345mm total depth. 

 

On 11/04/2019 at 09:39, Howard B said:

Also if it helps check out mrstairs.com. They have a nice online staircase design tool which will help you get a good reference for your space, even if you do not order from them.

 

Thanks - will check them out. 

[Mr Punter]

I think you will need an engineer to check the design. They may be able to advise where you can economise with materials. Will your welder do all the required fabrication?

 

Here is one we had made and it used a central rectangular section.  You could do similar and use 2 sections spaced apart a bit which would help stop any twist.

[Onoff]

6 hours ago, Nelliekins said:

Not really suitable for the space because the opening has been designed for a lift shaft to go down the "spare" area in the opening. 

 

One of the first passenger lifts in London was at the Prudential building in Holborn. That had a spiral staircase going up AROUND the lift shaft. All finished in mosaic tiles. The lift doors, in fact wrought iron gates exited the shaft onto the stair landings. In later years the lift mechanism was removed and open grilles put in at every level. I spent some happy hours in there with an angle grinder removing all the old stub brackets that supported the original guide rails. These had been deemed dangerous as they were so sharp.

 

Just saying...reminiscing...

[Pocster]

Helical stairs !!! ?

[Nelliekins]

On 17/04/2019 at 15:32, Mr Punter said:

I think you will need an engineer to check the design. They may be able to advise where you can economise with materials. Will your welder do all the required fabrication?

 

Here is one we had made and it used a central rectangular section.  You could do similar and use 2 sections spaced apart a bit which would help stop any twist.

 

I think a simple set of deflection calcs could be knocked up without an engineer. I ended up checking a bunch of our first engineer's calcs because I was being told by Logix and NUDURA that he was being overly cautious... 

 

Anyway, here's an improvement on the design... 

 

 

The stringers are underslung PFC 180x75x20. The white box section is 50x50x3. The treads are sat on cantilevered box section welded to the PFC. The 2 stubby little legs at the bottom affix the base to a steel beam set into the basement ceiling, which was designed to carry the weight of these stairs and the concrete ground floor as well.

 

Treads and risers are timber - spruce / redwood to start, oak or ash eventually.

 

Total weight for the staircase will be around 450kg, but at least half of that is loaded onto our steel reinforced concrete walls. 

 

Oh and the beams will be tidied up at the ends, and the landing covered with timber on top of joists in hangers every 300mm.

 

The handrail will be made from stud walls (4x2) bolted to timbers in the PFC webs, and braced at both ends by more handrail (it'll be continuous all the way through the 3 floors). 

 

Comments welcome!

Edited April 23, 2019 by Nelliekins
Missed some bits out

[Nelliekins]

It starts!! 

 

Not much to look at, this steel stuff... 

 

Rusted to within an inch of its life! Despite this, all about as sharp as you could possibly imagine - nearly sliced my finger off picking the first one up! 

 

 

Still, some judicious use of gauze and tape and ready to carry on. 

 

My part-time builder came round to help me chop the steel, weld it all up, etc. After a day, we aren't as far through as I expected... 

 

 

That's one cranked beam, made from 180x75 PFC, and installed adjacent the wall. It's standing on a leg near-side which runs down to an I-beam in the floor, and some 120mm Thunderbolts bolted through a welded plate into the reinforced concrete wall at the far end. The timber is covering the second cranked beam, which has since been fixed in place in the same ways. 

 

Those 2 cranked beams will form the bottom flight of stairs, once the 50x50x3 box section is welded and/or tek-bolted to the PFCs for each tread. Here's the side view:

 

 

On top of the landing part, we will be putting another pair of cranked beams (the same as these two but upside down) set at 90° (going up to the right) that will be welded onto a steel plate we have affixed to a double posi joist at the top of the stairwell. 

 

So far so good, but between the weather and the uneven ICF internal walls, it took 7 hours to get to this point... 

 

Let's hope tomorrow is more productive! 

[Tennentslager]

Your brave taking this on...but I’m cheering from the sidelines ??

[Onoff]

17 minutes ago, Tennentslager said:

Your brave taking this on...but I’m cheering from the sidelines ??

 

Cheering from underneath would show real support!

[Russell griffiths]

With regards the uneven walls @Nelliekins have you looked at an eps rasp, it’s like a massive surform that can rip down the surface to make it nice and flat before rendering

mark out your stairs roughly and smooth out any high areas. 

I have just ripped down a couple of high spots before fitting internal floors, works a treat. 

[Nelliekins]

OK so it didn't go quite to plan... 

 

Bottom flight seems perfect - exactly 190mm rise on each tread of 240mm (although the treads aren't fitted yet). However the top flight has gone completely wrong.

 

First, it transpires that using a spacer between treads when welding only works if it doesn't react to temperature... I used a piece of 140x38 CLS timber, having measured it first to confirm the size. However after getting warm through proximity to a welded joint, it distorted to 138mm on one side and 141mm on the other... But I didn't notice. 

 

Second, spacers are all well and good, but when the steel you're welding isn't actually the expected dimensions, you end up with an incremental error. Our 50mm box section came in 2 lengths - one was cut for the bottom flight and was nigh on perfect. The other was cut for the top flight, and according to a friend's caliper is 51.6mm. Doesn't sound a lot does it? However, that and the warped timber amounts to an error of 15.6mm on the top of a 6-tread flight. That's a problem. 

 

What's worse, there's a 4mm difference in the floor-to-floor height between where I measured and where the stairs start (because there's no way to measure directly where the stairs start - you have to use a laser to transfer the mark). So that's made the top step approx 20mm too shallow on the rise. 

 

Here's where we are at now - partially dismantled upper flight, so that we can adjust all the box section bits and make it right. Can't even do it in situ because the EPS isn't safe around fire! 

 

Edited April 30, 2019 by Nelliekins
Typo

[Nelliekins]

As an aside, I just noticed that although the PFC is marked as 180x75 its actually 180x90. Wondered why it was so damned heavy lifting into place! 

 

Next time I think I will use something lighter like 125x65, because this stuff is insanely strong / rigid and is massive overkill! 

[Nelliekins]

Ok so another visit from my welding friend, and we still aren't finished... ?

 

Making progress at least :

 

 

The old temporary status have been dismantled and the tread supports are now welded on fully. The "square" section for the landing is warped though - the top flight is 900mm apart from the top to the crank point, and then is 15mm too narrow where it goes into the wall. Rather than try to straighten the cranked beams, we are just going to pack off the face before the last riser. 

 

Next up is the handrail - we are going to place 1.5m lengths of 50mm box section welded to the side of the cranked beams on the right hand side (going up). 5 lengths, spaced at around 1 apart, should be good enough to attach a timber and plasterboard wall to... 

[Onoff]

Loving it. I might whack a temporary handrail up on that unprotected edge though!

[Nelliekins]

2 hours ago, Onoff said:

Loving it. I might whack a temporary handrail up on that unprotected edge though!

 

All being well it'll have a steel framed handrail welded on tomorrow, and nobody on site before that part gets underway anyway! 

 

The uprights for the handrail were cut this afternoon, and both the 4x2 timber and the plasterboard are in the garage ready to attach to it. We even have a variety of tek bolt lengths to get the best fit without sharp bits sticking through anywhere! ?

 

The treads are proving more of a challenge, actually. The basement stairs are just spruce planks chopped down to 900mm wide. I thought of doing the same here but since we have a load of oak doors going in am wondering if we shouldn't get a better match for them... 

 

Anyone know where to get cheap oak planks from? Looking for a big pile (30!) of 900x240x38 treads and 900x185x38 risers to match... 

 

For now I am going to saw through a set of scales planks I have lying around - the treads will be a bit short but they will easily carry over the 620mm span at least, and they only cost a tenner each!