Staircase timber

[pompeyjim]

I'm thinking of moving my staircase and I fancy having a go at it myself.

I've seen and read plenty of how to guides and I'm competent enough to do it but most things I see are American and they seem to build them with either 2 or 3 stringers made from 2 x 12 timber.

This seems over kill for our smaller UK stairs (probably 700 to 800mm wide and maybe 2.7 m high.

What's the standard timber used here for stringers? Most stairs I see look quite thin.

Thanks

[ayjay]

This seems over kill for our smaller UK stairs (probably 700 to 800mm wide and maybe 2.7 m high.

What's the standard timber used here for stringers? Most stairs I see look quite thin.

Thanks

The size will depend on the stairs. I've never had to build a flight with a size restriction so have never bothered about a minimum size I can use, but for the sizes you give I'd say 250mm X 38mm would suffice.

[pompeyjim]

Thanks, is there a general rule for working out what size to use? Like with joists there are span tables etc

[big-all]

yes 38mm but will tend to need to be machined to that size more likley to be nearer 41-44mm

[Job and Knock]

....but most things I see are American and they seem to build them with either 2 or 3 stringers made from 2 x 12 timber.

I'd hazard a guess and say that they are cut stringers, a type of stir construction common in the USA but rarely used here. Ceariainly some of the techniques I've seen used in the USA just wouldn't get past a BCO in the UK

What's the standard timber used here for stringers? Most stairs I see look quite thin.

For a closed riser staircase it's normal to use something like 250 x 32 to 38 or 275 x 32 to 38 section (finished sizes) in a clear grade redwood or slightly thinner stuff, of 32 or 35mm thickness is hardwoods such as oak. This is supplied specifically as stair stringer material by any half-decent timber merchant and should be ex-stock (so forget B&Q, etc!). In softwood your treads should be something like 28 to 32mm thick. Whilst stairs you have seen may seem thin (and some new builds have horribly thin stair stringers with MDF treads, UGH!), the wedges and glue blocks do effectively make the staircase as strong as a box or girder structure when properly executed

[pompeyjim]

For a closed riser staircase it's normal to use something like 250 x 32 to 38 or 275 x 32 to 38 section (finished sizes) in a clear grade redwood or slightly thinner stuff, of 32 or 35mm thickness is hardwoods such as oak. This is supplied specifically as stair stringer material by any half-decent timber merchant and should be ex-stock (so forget B&Q, etc!). In softwood your treads should be something like 28 to 32mm thick. Whilst stairs you have seen may seem thin (and some new builds have horribly thin stair stringers with MDF treads, UGH!), the wedges and glue blocks do effectively make the staircase as strong as a box or girder structure when properly executed

Thanks. Regards what I've seen in USA they seem to use regularised 2 x 12 and just mark out with a rafter square and cut with a circular saw then put some trim on the outside. They seem to love putting 'trim' everywhere they can

[Dave54]

I think I've said before that we needed a couple of staircases made some years back. There was (and still is) a local company who were very competitive on price when you consider the costs of making them yourself. It's worth finding out what the costs are.

[Job and Knock]

Regards what I've seen in USA they seem to use regularised 2 x 12 and just mark out with a rafter square and cut with a circular saw then put some trim on the outside. They seem to love putting 'trim' everywhere they can

It's maybe worth noting that "regularlised" 2in stock in the USA generally works out about 38 to 40mm in any case, US actual timber sizes are very undersize when timber is dressed as they quote sizes based on raw, sawn, unkilned size. Pine shrinks quite a bit when it's kilned, so that 2in rough sawn green timber will often dry to about 1-3/4in (44mm) and that's before then run it through a 4-sider. In strength terms, though, the Yanks do tend to nail everything (and I mean everything - they often nail door linings in place using a 15ga nailer because the houses are timber framed, the cut-outs they go into are often very tight (so few packers) and their casings are relatively thin these days - you can';t do that sort of thing in masonry-walled houses) - and nailing produces a far weaker joint that our wedged and glued approach IMHO

As far as trim goes it's also a speed thing - framing I've seen in the USA is horrendously rough and drywall finish around door and window openings means there's lots of scope to hide the bad stuff - hence a lot of trim which is sawn and nailed really quickly to cover a multitude of sins - then sold as "sophisticated ornamentation"). Believe me, I'm a shop fit joiner and we do a fair bit of hiding the shoody work of other trades!

[Joiner1998]

I build a lot of staircases and use 265mm x 28mm southern yellow pine. It's straight grained and pretty hard for a softwood which gives you a good firm staircase.
As for tread thickness, I've seen treads in older houses as thin as 20mm. I typically use 25mm (MDF / timber) unless specified otherwise. You just need to remember you'll need to add glue blocks to and treads under the thickness of at least 35mm

[Job and Knock]

I've seen treads in older houses as thin as 20mm. I typically use 25mm (MDF / timber) unless specified otherwise.

Round here really thin treads down to 3/4in (19mm) or 7/8in (22mm) was generally only used on cheap stuff such as poorer terraced houses (mostly demolished these days) or back of house (servants quarters) in big Victorian houses. I know that even our crabby little 1880s terrace house has 1in (25mm) softwood treads which match the floor boards. TBH most of the inter-war or even postwar semis I've seen are 15/16in (22mm) or 1in (25mm) thick, but maybe that's because of local practice. I know it's the modern thing to use 25mm (or even 22mm) MDF as treads, but I think it's still a cheap and nasty solution being the very minimum you can get away with within the Building Regs. 25mm MDF isn't as rigid as the same thickness of a decent redwood softwood and I've visited enough new houses to know that you can at time feel the treads flexing beneath your feet when walking upstairs (or more often lugging heavy stuff up or down the stairs). But then a lot of new builds also have saggy, creaky, badly installed floors, too, which the building trade seem to view as acceptable

[dewaltdisney]

I was wondering if composite boards are ever used? I guess routing out the stair housings might weaken the stringers? Just wondering.

DWD

[dewaltdisney]

What I was thinking of was not composite, I meant laminar timber as the stringers?

DWD

[Job and Knock]

What I was thinking of was not composite, I meant laminar timber as the stringers?

I've seen laminated (plywood-like) stringers on spiral staircases as well as "bricked" solid timber (so-called because the short lengths of timber are layered together in a brick bond pattern) but it's normally too expensive to use those techniques for a straight stringer. They are also considerably thicker than a straight stringers in order to give more strength, although some more modern constructions do use either fibre glass or even carbon fibre layers to increase the strength of the structure. The only places I can recall installing glulam stair components was on big corporate staircases where the gluelam beams had tread units bolted down onto them. Big and expensive

[steviejoiner74]

I fitted a straight flight from “stairbox” on Friday. House we are renovating just now needed new straight flight and we gave them the sizes and spec we needed. 196 quid delivered within 10 days and fully constructed. Given that it was bespoke and so cheap I was surprised at the quality,35mm redwood stringers,yeah the treads and risers are MDF but it’s well built and I would use them again.

[dewaltdisney]

I remember now where I saw it that stirred the memory. It was a newly built church that also had community use rooms upstairs. I was there for a meeting and I recall going up a set of stairs made out of laminar timbers. They were quite thick sections now as I recall and it was the first time I had seen anything like it it so I filed it away in my mind as an interest. The church part had very long curved laminar beams forming the roof and sides and it was quite spectacular.

Thanks for that J&K it jogged my memory but it is wholly unrelated to this thread.

DWD