Pre-cast concrete staircase

[flanagaj]

Has anyone investigated pre-cast concrete stairs and if so, do they too require a lot of structural engineer input in relation to the walls / floor makeup of the house?  I originally was thinking about a floating staircase, but this requires the mounting wall to be significantly beefed up.  So now, I am wondering whether a pre cast staircase could be a better option.   In fact, given we want an industrial look to the entrance hall, it might actually be a better option.

[-rick-]

How about Steel?

 

Still looks industrial, easier to install, probably a bit more expensive to buy but depending on your design asthetic might look better. Can either get them with one string in the centre and open sides or strings either side. (Is strings the right word?)

Edited Sunday at 09:40 by -rick-
Oops, realised I edited out the point of my post.

[nod]

Normally go in before the roof 

[Mr Punter]

They can be quite expensive.  I have used Bison ones before, where they were also doing hollowcore plank first floors.  It is nice to have stairs and first floor in early on for safety and access.  You need to consider what the finishes and floor heights are going to be.

[JohnMo]

9 hours ago, flanagaj said:

pre-cast concrete stairs

Think I would install before the external walls so you can get a crane in with ease.

 

Concrete floors, concrete stairs, will it start to look like a carpark or industrial building?

[Nick Laslett]

10 hours ago, flanagaj said:

Has anyone investigated pre-cast concrete stairs and if so, do they too require a lot of structural engineer input in relation to the walls / floor makeup of the house?  I originally was thinking about a floating staircase, but this requires the mounting wall to be significantly beefed up.  So now, I am wondering whether a pre cast staircase could be a better option.   In fact, given we want an industrial look to the entrance hall, it might actually be a better option.

I have concrete stairs and a concrete first floor. 
 

The foundation design will need to accommodate a concrete stairs. My structural engineer needed to know the stairs design, before he finalised the foundation design. We needed an additional concrete pad under the insulated raft at the bottom of the stairs. 
 

I did investigate Millbank for pre-fabricated stairs, but the ICF guys built the form work for the stairs in-situ, and poured the concrete the same time as the first floor walls. 
 

https://www.milbank.co.uk/products/stairs/stairs-and-landings/

 

For me, concrete first floor and stairs were an integral part of my design requirements from the beginning, even before deciding to go with ICF, which actually made it much easier. The ICF guys did my stairs at no additional cost, which was very generous of them. 
 

Here are some other links I have from my early research. 
 

https://www.ejbformwork.co.uk/in-situ-concrete-stairs/

 

https://midwest-stairs.co.uk

 

Picture of the form work for our stairs. 
 

 

 

 

[BadgerBodger]

Precast stairs are not a good option for much other than a straight flight or a stair core. 
 

they are HEAVY ( think a flight of 12 steps was 1.4t on my last job and if had flights with half landings weighing up to 3t before) and unless within a dedicated structure (like a precast stair core) they require a lot of engineeering consideration. 
 

they certainly ain’t gonna give the impression of anything floating. 
 

cast in situ however… 

 

 

but both would need a lot of engineering. 
 

 

[Gus Potter]

10 hours ago, flanagaj said:

In fact, given we want an industrial look to the entrance hall, it might actually be a better option.

Does this sort of thing float your boat,  it's stand alone, you can make it as industrial as you like. 

 

I made a post earlier about your cantilever stair but what about this.. it can be free standing?

 

 

 

The great thing about these is that the steelwork is not too expensive, they get churned out by fabricators day in and day out and depending on your budget you can pick and choose the treads depending on how much money you have left as you near the end of the build.

 

@markc earlier knows a lot about this kind of stuff and how you fabricate them so have read back on his posts. He has talkedf about in past about how these type of stairs twist a bit due to welding heat an so on.. but that comes with the "industrial look"

 

BIG point.. these types of stairs need a strong support at the top and bottom (to stop twisting) so you need to plan for that early on. 

 

Good thing is that you install near the end of the works to mitigate damage risk. 

 

SE wise they are easy to design but the connections at particularly the top need some thought as you need to get the stairwell trimming sorted out so it take the twisting (stair torsion). The bottom conection  is often easy as you have a base plate that can take some twisting. 

 

There are lots of posts on BH where folk have discovered late in the day that their stair top  trimming is lacking strength and robustness and that causes lots of grief. 

 

These stairs can look great!

 

You have the tread detail, then how you do the steel paint finish, how much you want the welds finished, the balluster / glass detail. You have many options from high end to totally industrial look.. rough as.. 

 

The best advise I can give you as a past self builder and designer is make your mind up now about the way the stair is going to work structurally. Build the support structure in and then as you near the end of the job see how how much you want to spend on the stair finishes (glass, quality of the treads etc) and how that fits with the other budget constraints you discover as you have gone along. 

 

It's a hard decision as the stair is a main feature of the house.. the first thing folk see when they come in, been there and worn the tee shirt. 

[Gus Potter]

To add a bit.

 

How industrial do you want say the welding to look if going for the stair in my last post?

 

@ETC here we are considering the important detailing and finish. How that interacts with the tread appearance, the balluster and so on, even the pitch and tread length of the stair is important to get an appealing looking stair which is often a main feature of the house. 

 

 

@flanagaj as an SE so long as the welds have an adequate strength then all is good. But the ripple weld is more industrail.. good steel fabricators can do both and all you need to do is tell them, please do this type of weld. 

 

Next is paint finishes (if any, could be a clear varnish but we need to check the fire protection)  and what goes well with timber treads and balustrades. 

 

All this does not need to cost the earth but to get best value it takes thought time. 

 

You have enough on your plate to get your self build underway but the KEY is pick the structural design of your stair in the context of what you need to build now and then have fun later on the detailing and choice of glass or what ever handrail / glass and so on you want. Don't forget that your design may evolve and what you are thinking now may change.. keep your options open, appreciate that this is one of the benefits of self building. 

 

What I can tell you from my own experience is that the design will evolve so try not to tie your own hands too much at the moment. 

 

Last thing is don't forget the building regs.. any gap roughly needs to be less than 100mm! So a lot of these stairs you see are non compliant including the one I posted above!

 

 

[flanagaj]

44 minutes ago, Gus Potter said:

Does this sort of thing float your boat,  it's stand alone, you can make it as industrial as you like. 

 

 

 

Unfortunately, they are not my thing.  I don't like the central spine.  I am now contemplating cast concrete stairs, but if that comes with it's own requirement regarding having to have a special concrete floor as opposed to sitting on the 150mm slab we have proposed, then it might be back to the drawing board.

[ETC]

Any precast floor manufacturer will do precast stairs. Not rocket science and the manufacturer will measure on site and install the stairs. 

[flanagaj]

4 minutes ago, ETC said:

Any precast floor manufacturer will do precast stairs. Not rocket science and the manufacturer will measure on site and install the stairs. 

Do you know whether they require a specialist foundation underneath the concrete slab?

[Gus Potter]

6 minutes ago, flanagaj said:

Unfortunately, they are not my thing.  I don't like the central spine.  I am now contemplating cast concrete stairs, but if that comes with it's own requirement regarding having to have a special concrete floor as opposed to sitting on the 150mm slab we have proposed, then it might be back to the drawing board.

Ok this is good, design is often about ruling out the things you don't want and that lets you focus on the things you do want! 

 

So you have precast treads... do you envisage these being cantilevered? 

 

I think you have to go back to the drawing board. I get it, it's a major design decision. 

 

Keep posting, don't give in, loads of folk on BH are able to help..

 

But don't forget.. you are helping others that will come after you might read this thread!

 

 

[ETC]

Not sure but wouldn’t think so. The ones I’ve seen sit on the ground floor slab. If you contact any of the precast concrete suppliers they will tell you what if anything you will need.

[ETC]

2 hours ago, Nick Laslett said:

I have concrete stairs and a concrete first floor. 
 

The foundation design will need to accommodate a concrete stairs. My structural engineer needed to know the stairs design, before he finalised the foundation design. We needed an additional concrete pad under the insulated raft at the bottom of the stairs. 
 

I did investigate Millbank for pre-fabricated stairs, but the ICF guys built the form work for the stairs in-situ, and poured the concrete the same time as the first floor walls. 
 

https://www.milbank.co.uk/products/stairs/stairs-and-landings/

 

For me, concrete first floor and stairs were an integral part of my design requirements from the beginning, even before deciding to go with ICF, which actually made it much easier. The ICF guys did my stairs at no additional cost, which was very generous of them. 
 

Here are some other links I have from my early research. 
 

https://www.ejbformwork.co.uk/in-situ-concrete-stairs/

 

https://midwest-stairs.co.uk

 

Picture of the form work for our stairs. 
 

 

 

 

That looks like an awful lot of work.

[torre]

43 minutes ago, flanagaj said:

, they are not my thing.  I don't like the central spine.

Nothing to stop you using steel but as a double stringer

[flanagaj]

2 minutes ago, Gus Potter said:

So you have precast treads... do you envisage these being cantilevered? 

Cantilevered would be the ultimate aim.  But it's achieving that without breaking the bank.  My plan was something like the following.  Ideally, getting the metal structure to counter the forces being applied as opposed to the wall having to do it.

 

[Gus Potter]

As a cursory inspection that won't get past a UK SE. 

 

The wall fixings into your proposed blockwork will fail drastically and the wall stringer is too flexible. The diagonal tread bracing is a straw man. 

 

Keep up with the ideas, something that suits your budget will come to light. 

 

How much have you allocated in your budget for the stair? 

[flanagaj]

9 hours ago, Gus Potter said:

How much have you allocated in your budget for the stair? 

Ideally, no more than 7K
 

[Russell griffiths]

That picture is only showing half the story, the flex in those hollow steel sections will be immense. 
that staircase will have a glass balustrade  to take the flex out at the far end. 
 

im obviously not a structural engineer, but just look at that picture, there is not a hope in hell of those steel outriggers holding a man’s weight if he was to stand on a single tread at the furthest point from the wall. 
 

be carful of pictures taken halfway through a job. 

[saveasteading]

Precast stairs are great for car parks and heavy industrial use and for fire resistance. Esp if integrated with a precast structure.

Last time I used them, the geometry was set so there were limitations on dimensions and the rake.

They need wall or beam support at the top.

 

If I wanted concrete stairs in a house they would be in-situ as the photo above. They will still need support at the top.

[Nick Laslett]

6 hours ago, saveasteading said:

Precast stairs are great for car parks and heavy industrial use and for fire resistance. Esp if integrated with a precast structure.

Last time I used them, the geometry was set so there were limitations on dimensions and the rake.

They need wall or beam support at the top.

 

If I wanted concrete stairs in a house they would be in-situ as the photo above. They will still need support at the top.

As @saveasteading  says, you need some specific preparations for concrete stairs. We have 150mm thick concrete ICF walls on three sides of our stairs. The distance between the walls sets the rake. Rebar goes into the side of the wall as the stairs go up. 
 

 

Edited Monday at 15:41 by Nick Laslett