I am getting started on building a set of stairs for my house. I am planning on using housed stringers. The stringers/risers will be painted so I am looking for some advise on material for the stringers. I pln to se mdf or mdo for the risers. Would either of these material be suitable for the stringer.
There will be a landing in the stair so the longest stringer will be less than 8′. I have the ability to vacum bag the material together if necessary to build whatever thicknes is necessary for strength. I was thinking of laminating 2 1/2″ pieces of mdo or 2 3/4″ mdf. Either one will give me a great surface for paint. I’m just not sure if the mdf would have the necessary strength though it will be fastened to studs on both sides of the stair so it may not be much of an issue.
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I would use 5/4x 12 poplar.
It sounds like the stair is capped by a wall on both sides?
I would use solid wood, or maybe birch plywood or mdo with a solid wood (not veneer) edging on top. The top edge of the mdf is too fragile.
The top edge of the stringer will be getting capped with solid wood so the durability of the edge isn't really a concern. I considered solid wood but figured with the wide stringer I would have wood movement issues to deal with.
I am primarily a furniture/cabinetmaker so I may be overthinking the wood movement issues.
In that case I'd use whatever materials you are most familiar with. Because of the angle of the stringer, as long as solid wood is dry it won't move much. The biggest advantage to the mdf would be cost and paintability.
When you say housed stringer do you mean a grooved and shimmed riser and tread? If that is the case, I would go with solid stock. I don't really know though, I have never heard of carpenters using mdf for them. I would go plywood before mdf, I think. But poplar would paint up nicely.
Have you checked out Scott Schuttner's Basic Stairbuilding? It has some info on housed stringers. It would be cool to see some work in progress pics when you get started.
PL Polyurethane construction adhesive is awesome for "squeakproofing." You probably knew that.
Dustin
Tom
I dont think I'd use MDF for stringers - be to concerned about the strength of it.
Bag a couple pieces of ply together and that would be much stronger then any solid material that you can find. If your planning on finishing/caping the edge then thats a non-issue.
Doug
Thanks Doug, that's likely what I will do.
MDF shouldn't be used on stairs for a number of reasons, most of which are structural. Instead of thinking through your own ideas for materials, it's probably better to use time tested designs until a better feel for what works and doesn't is developed.
Best of luck.
Beer was created so carpenters wouldn't rule the world.
I know mdf can be used in some pretty sturdy structural applications. I've built several torsion box tables and bed rails with 1/4" mdf and honeycomb. Trying to find what some time tested material are was the idea behind my posting.
This is for my own home so I'm not opposed to experimenting a bit with different materials.
I don't think mdf or medex is structurally rated.
It definitely doesn't hold up to bumps and scrapes, as mdf base and case trim has shown.
Either of those reason is good enough that I wouldn't use it.
Locally mdf wouldn't pass code if used for just about anything stair related other than non-structural surfaces unless the plans had an engineer's stamp on it.
Risers provide such a large amount to a stair design's overall stiffness and are responsible for so many squeeks, that it's a pretty important piece of the puzzle.
Even if mdf risers were to hold up to the compression of being walked on, and with a good bond of pl they probably would if kept dry, how is the riser supposed to hold onto the inside portion of the tread below it? Plywood or solid wood holds screws quite well in this situation that produces a lot of sheer on the fastners. Sheer and mdf don't seem to go hand in hand.
3/4" AC or 1-1/8" decking ply is selling for not much more than $35/sheet so for a set of stairs that clients are paying thousands for, saving a few bucks on sheet goods wouldn't make sense.
While I'm quite aware that cabinet makers and many finish carps love MDF for shelves, weight bearing cabinet parts and other such uses, many fail to appriciate the difference between short term deflection and long term sag. I could care less what the short term deflection or performance is if 10 years down the road the piece has to be rebuilt to look right.
I'm not trying to bust your chops, it's just that better materials are readily available and much more commonly used.
Good luck.
Beer was created so carpenters wouldn't rule the world.
MDF sags badly over time. It is not a structural material. Do not use it for stairs.
For full-span one-flight stringers for a set of housed stairs, I would use nothing less than 8/4 solid lumber, and the same for the treads assuming a tread width of 36"-42". I like open back stairs, so I don't often use risers, but they obviously don't have to be as thick as the treads or stringers. You could get by with 5/4.
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Hi Tom,
Like most have said, I'd definately shy far away from using MDF for housed stringers. Actually I personally would shy away from using anything but solid, select-grade, and dry lumber. As far as species goes, like Jay said before you can't go wrong with 5/4 x 10 or 12 poplar. For me, I'm able to get 5/4 x anything clear pine easily and that's usually my first choice. Also as said, wood movement shouldn't be too much of an issue due to the orientation of the treads and risers to the stringers. Be sure to use A LOT of glue, tight-fitting wedges, and well-placed pocket screws to assemble.
In any case, good luck.
Nick