(I posted this in alt.home.repair but I thought I'd ask the folks in
here too since I know a lot of you do this kind of work.)
I am about to rebuild some stairs and I'd like some feedback on
whether my ideas for the treads are going to work or not.
I have some enclosed stairs 39" wide with only two stringers on the
outside edges. Adding a middle stringer would mean some major
construction due to the way things are laid out. Currently, the
treads are 2x lumber with carpet. Naturally, removing the carpet
reveals that the 2x's are not flat, or straight, or in any way
suitable for my new treads. I'd like to use plywood to make new
treads for stability and flatness.
I plan to glue and screw two layers of 3/4" plywood for the treads.
This will give me roughly the same height as the old 2x's. The front
edge of the tread will sit on top of the riser below for support.
Will that be sturdy enough considering the span and lack of center
stringer? I'm thinking that I need to support the back edge of the
treads as well and I've had a couple wild ideas for how to do that.
One idea is to have each riser drop below the back of the tread and
cut a dado in the riser that the tread can slip into at the back.
Another idea is to use a double row of biscuits to join the back of
the tread to the face of the riser.
I've also thought about modifying the dado idea and just gluing on a
ledge that the tread sits on rather than milling a dado. The face to
face glue up for the ledge should be very strong.
Then there's the idea of mounting "joists" across the stairwell just
below each tread.
The question is, do I really need to do this or will the 1-1/2" of
plywood be stiff enough over time given that the front edge will be
supported?
Here's a picture I threw together for the first section of stair that
I'm redoing.
http://www.pobox.com/~DaveA/treads.jpg
It's only a 16" stepdown with two treads. This one I could easily
rebuild with all the stringers I want but I'd like to use it as a
model for my main stairs so I'll have my process down when I get
there.
On Sat, 06 Mar 2004 11:27:37 -0700, David Alexander <[email protected]>
wrote:
>(I posted this in alt.home.repair but I thought I'd ask the folks in
>here too since I know a lot of you do this kind of work.)
>
>I am about to rebuild some stairs and I'd like some feedback on
>whether my ideas for the treads are going to work or not.
>
>I have some enclosed stairs 39" wide with only two stringers on the
>outside edges. Adding a middle stringer would mean some major
>construction due to the way things are laid out. Currently, the
>treads are 2x lumber with carpet. Naturally, removing the carpet
>reveals that the 2x's are not flat, or straight, or in any way
>suitable for my new treads. I'd like to use plywood to make new
>treads for stability and flatness.
>
>I plan to glue and screw two layers of 3/4" plywood for the treads.
>This will give me roughly the same height as the old 2x's. The front
>edge of the tread will sit on top of the riser below for support.
>Will that be sturdy enough considering the span and lack of center
>stringer? I'm thinking that I need to support the back edge of the
>treads as well and I've had a couple wild ideas for how to do that.
>
>One idea is to have each riser drop below the back of the tread and
>cut a dado in the riser that the tread can slip into at the back.
>
>Another idea is to use a double row of biscuits to join the back of
>the tread to the face of the riser.
>
>I've also thought about modifying the dado idea and just gluing on a
>ledge that the tread sits on rather than milling a dado. The face to
>face glue up for the ledge should be very strong.
>
>Then there's the idea of mounting "joists" across the stairwell just
>below each tread.
>
>The question is, do I really need to do this or will the 1-1/2" of
>plywood be stiff enough over time given that the front edge will be
>supported?
>
>
>Here's a picture I threw together for the first section of stair that
>I'm redoing.
>
>http://www.pobox.com/~DaveA/treads.jpg
>
>It's only a 16" stepdown with two treads. This one I could easily
>rebuild with all the stringers I want but I'd like to use it as a
>model for my main stairs so I'll have my process down when I get
>there.
if you decide not to suport the middle they will be weak. you realy
should add a middle stringer. a dado on the riser may work. 2 layers
of plywood would be strong enough but in all of these fixes you are
trying to eliminate movement when the steps are walked on. movement
under stress will produce squeeks.i would use standard stair tread
wheather it be oak or SYP is up to you.oak treads are sturdy but
rather expensive. subfloor adhesive or liquid nails should be used.
dont be affraid to put the glue in. the more the better..again the
best way would be to cut in a middle stringer. it isnt that difficult
to do. line each side with a 2x4 for added strength. skeez
"David Alexander" <[email protected]> wrote:
> I have some enclosed stairs 39" wide with only two stringers
...
> I plan to glue and screw two layers of 3/4" plywood for the treads.
> This will give me roughly the same height as the old 2x's. The front
> edge of the tread will sit on top of the riser below for support.
> Will that be sturdy enough considering the span and lack of center
> stringer? I'm thinking that I need to support the back edge of the
> treads as well and I've had a couple wild ideas for how to do that.
...
David, I agree that 30+ inches is a large span for a tread. Do the 2x
treads feel bouncy now? I suggest using a "lock joint" made by extending
the TOP tread layer about 1/4 inch or more into a 3/4" wide dado in the
riser. This avoids having to make the riser drop below the tread bottom and
provides lots of glue surface. After all the glue dries the 1 1/2 in tread
and lock joint will be strong and stiff. Another alternative is to cut back
the LOWER tread layer and glue and nail in a rail that is, say 3/4 by 3".
This is similar to your idea of adding a "joist" under each tread. This
second alternative has the advantage of not involving the riser in the
tread stiffening system. You could even layer the rail by face gluing a
second 3/4 by 2 1/4" piece to it, or by using a piece of lumber and cutting
a rabbet along the top edge. This would provide a double step lock joint
giving even more glue surface. In every design I am assuming your cuts will
be straight and smooth so you can use woodworker's glue to provide strong
bonds. I think your idea of using biscuits will work fine also, although I
believe a double row would be overkill.
In conclusion, I would avoid notching the two existing stringers to
accomodate extended risers or tread rails or tread joists unless those
stringers are MUCH beefier than normal. Such notches create a stress point.
If you extend the risers down, notch the risers so the extended part fits
BETWEEN the stringers. Like wise, any tread rails or joist supports should
fit between the stringers. It is my belief that your laminated 1 1/2"
treads will be plenty strong, but without any middle stringers, they will
have an annoying bounce and a disconcerting tendancy to bend under load. I
think your "wild" ideas are on the right track, er I mean the right-angle,
but are over engineered. The main goal is to stiffen the tread. You could
probably get by with just a butt joint between the tread and riser if it is
true and square and glued up well.
I like your picture. What did you use to create it? Here is a reference on
treads, risers, and nosings you should look at before you finalize your
design:
http://www.access-board.gov/adaag/html/adaag.htm#4.9
I hope these suggestions help. If any of it is unclear, request a better
description. Let me know how the project goes.
jj