Hi.
is 23mm thick parana strong enough for stair treads at 71cm width?


Thanks.

Arthur

Arthur2 wrote:
Hi.
is 23mm thick parana strong enough for stair treads at 71cm width?


Thanks.

Arthur

Arthur,

On a 'normal' staircase with treads and risers, yes for walking on - but
not for driving a mini down though, but who knows, it may even take that
sort of loading :-)

If you are making an 'open' tread staircase (no risers) then 30mm (minimum)
would be the better option.

Brian G

Arthur2 wrote:
Hi.
is 23mm thick parana strong enough for stair treads at 71cm width?


Thanks.

Arthur

Arthur,

I've just had a look in an old book of mine and it would seem that 23mm
would be a little shy for a stair tread and I have posted some drawings on
tinypics.com that may be of some help for sizing - as I'm an old dinosaur
(along with the book) you will have to convert from imperial to metric
measurements.

1 - http://i13.tinypic.com/4taseie.jpg

2 - http://i8.tinypic.com/4vil4ps.jpg

Sorry about the 'bum' info

Brian G

Note that those drawings include a central support carriage!

Arthur2 wrote:

is 23mm thick parana strong enough for stair treads at 71cm width?

A bog standard commercial prefab staircase will use 19mm MDF on the
treads (assuming we are talking closed riser here), so 23mm sounds
adequate.

The set I built used 19mm MDF on the treads, 12.7mm MDF on the risers
and the result is solid and creak free.

http://www.internode.co.uk/loft/stairs.htm

If I were building them for display (i.e. polished etc rather than
carpeted) then I would have built them "heavier" to improve the visual
appeal, and reduce the noise transmission)

--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
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wrote:
Note that those drawings include a central support carriage!

That looks as if it is as much for supporting the plastered soffit below
as the stairs above.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
...
Arthur2 wrote:

is 23mm thick parana strong enough for stair treads at 71cm width?

A bog standard commercial prefab staircase will use 19mm MDF on the treads
(assuming we are talking closed riser here), so 23mm sounds adequate.

The set I built used 19mm MDF on the treads, 12.7mm MDF on the risers and
the result is solid and creak free.


Is 23m pine stiffer than 19mm mdf?

Arthur

Arthur2 wrote:
"John Rumm" wrote in message
...
Arthur2 wrote:

is 23mm thick parana strong enough for stair treads at 71cm width?
A bog standard commercial prefab staircase will use 19mm MDF on the treads
(assuming we are talking closed riser here), so 23mm sounds adequate.

The set I built used 19mm MDF on the treads, 12.7mm MDF on the risers and
the result is solid and creak free.


Is 23m pine stiffer than 19mm mdf?

I would expect so. MDF is quite strong when constrained, but is fairly
weak when not fixed at the edges (too much load and it de-laminates and
behaves like a leaf spring!). Pine is stronger (along the grain at
least), but at the same time is less dimensionally stable so more likely
to come unfixed over time. Since the pine is also much stronger in one
direction than the other, it lends itself to getting nice stiff treads,
but you don't want too much nosing overhanging the front of the tread if
you are using thinnish material.

Note that with a well made stair, the flexibility of the tread is far
less important than you might think, since it is the stiffness of the
riser that is supporting the tread and taking the bulk of the load
(which tends to be toward the front of each tread). A 200mm deep riser
of MDF or ply is of formidable stiffness vertically even if only half an
inch thick (the rebate in the underside of the tread will also prevent
it buckling under load. It it also worthwhile making sure the risers are
very well glued, wedged, and possibly pinned into place as well to keep
them in place.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/