3 or 4 stringers on my 1100 wide staircase to be tiled?

[tobbew]

Hello

I am building a staircase that will be tiled.

It is being built in a stairwell, with stringers on both sides that follow the wall, so it's not free-standing.

Then it's cc105 and so on, which I wouldn't dare to tile.
If I put in a stringer in the middle, which would then be free-standing, it becomes about cc55. If I add two, it becomes cc35 or something like that.

Some dimensions:

The staircase is 10 steps long and is about 160 cm high, and a stringer is 280 cm long.
The wood is 45 x 145.

The steps are made of 15 plywood laminated in three layers (45mm).

So, do we think one free-standing stringer in the middle, or two?

It seems wise to take and use two, but I have no idea about the deflection of a step made of this material, so maybe it's an entirely exaggerated dimensioning?

Pictures are available on the Facebook page, which might be a little guiding on how things look.

Thanks!

 

[thomasx]

With three pieces of 15mm plywood glued to a 45mm thick step, you can probably quite comfortably settle for two stringers on the sides and have the steps completely self-supporting.

Start by making one step and try it on the slope, and you'll see.

 

[nino]

Yes, I probably have to agree with thomasx, then it depends a bit on which tile you will have, a larger tile helps even if it's not much.
What are you gluing the plywood with, regular wood glue?
Make a step and place it on blocks and step on it. Maybe it's possible to build a flat iron into the step somehow if it gives. Another stringer in the middle should then suffice otherwise.

 

[thomasx]

If you are going to have risers, they will stabilize quite a bit as well, when properly mounted.

 

[tobbew]

Interesting, so what's in the middle might not be important? I'm a typical over-dimensioner, but it's always nice to hear that you might be able to skip a step.

Tiles are 30x30. Byggmax has a tile with "grooves" on it (a variant in the terrace series) that feels a little extra secure to have in a staircase.

How do you mount risers that stabilize? I suspect the basic idea is that it should be attached to both the step below and above, to stabilize properly?

Thanks for all the tips, now I have a bit to think about today, while I measure out all the "triangles" that will support the treads that will be attached after the stringer.

 

[toolman77]

No matter how stiff you make the staircase, the wood will move slightly with temperature and humidity. I think you should have some dead material on the steps that you then attach tiles to.

 

[thomasx]

Attach the riser to the back edge of the lower tread and underneath the upper one. Screw and glue.

And as mentioned, place gypsum between the tiles and wood.

 

[tobbew]

Isn't plywood pretty dead? I chose plywood instead of 45x220 on someone's recommendation, I thought the argument was that the board was dead. But plywood might have other strengths.

Then I was thinking of finding some super adhesive between the boards. Maybe regular construction adhesive will do, but otherwise, I'll buy something extreme.

If gypsum is needed, I'll probably remove a layer of plywood since the height is exact.

 

[tobbew]

OK, after searching around a bit, it seems like it's a bit risky to test without plasterboard. Is regular wall plasterboard sufficient, or do I need to get floor plasterboard? I have wall plasterboard at home; otherwise, I'll need to buy floor plasterboard.

This is for steps that are about 110 x 24 cm.

Thanks for the tips!

 

[nino]

I would bet on floor plaster, glued with ardex s48, then you get extra security.

 

[Jörgen Ö]

Honestly, I think laying tiles on a wooden staircase is asking for trouble. A wooden staircase constantly moves, both from usage and because the wood shifts as mentioned earlier. If I had received a request to do this, I would definitely decline, but now you're doing it yourself. Perhaps I sound negative, but I only see upcoming problems. IF you still want to proceed with this, I would use 9mm renovation gypsum instead of regular gypsum, glued with a good adhesive. That way, you also save some height, as regular gypsum plus s48 builds up at least 16-18mm or more. Then I would also fix the tiles using adhesive. You can usually get the tiles to sit fairly well, regardless of the surface, but the grout preferably requires gypsum to avoid cracking.

 

[thomasx]

Then there is surely sealant that allows for some movement without cracking?

 

[tobbew]

Laying tiles on a wooden staircase, I honestly think, is asking for trouble. A wooden staircase moves all the time, partly due to foot traffic, and partly because, as mentioned earlier, the wood itself moves. If I were asked to do this, I would definitely say no, but since you're doing it yourself, maybe I sound negative, but I only foresee problems. IF you are going to proceed with this anyway, I would use 9mm renovation plasterboard instead of regular plasterboard, glued with a good adhesive. This also saves you some height, as regular plasterboard plus s48 builds up at least 16-18mm or more. I would also use adhesive to set the tiles. You can usually get the tiles to adhere quite well, regardless of the substrate, but the grout preferably requires plasterboard to avoid cracking.

Hello

Thank you for your thoughts. I understand you; I'm not a hundred percent sure it will work, but I'll give it a good attempt and a fair try. That's partly why I'm using plywood too, because it moves less than regular wood. The stringer is screwed and glued firmly and I've even shortened the staircase by three steps (from 13 to 10 steps) and made the bottom three from leca for extra stability (and moisture-proofing from the garage). I'm even prepared to add a fourth stringer, making it like cc35, so it should be as stable as a hallway floor - which people are happy to tile.

 

[Jörgen Ö]

Absolutely, there is flexible grout (in most of them nowadays), but they do not accommodate very large movements, they are still cement-based.
However, it is possible to grout with soft grout, a bit more work, but it might be worth it in this case

 

[thomasx]

I find it hard to see this moving more than any other tiled surface. Each step has a very small surface area and generously sized dimensions.

It would be the transition between riser and tread, if the riser is also to be tiled. There it might be a good idea to use a tile trim.