"HeyBub" writes:

blueman wrote:
"hr(bob) " writes:

On Feb 6, 9:42 pm, blueman wrote:
One of the 12" wide treads on our main staircase has an ~18"
longitudinal crack in it. As per an earlier thread, the consensus
seems to be that these treads are 150 yr old heart pine.

Here is a link to a pic:
http://96.252.37.8:8080/public/1stFlrTread.jpg

I am not concerned about the visual look of the crack (if anyting it
adds "character") but the area under the crack is not well
supported and gives a bit when you put weight on it -- in fact, the
absence of such support may be the proximate cause of the crack.
The crack has probably been there for many years.

Since replacing the tread is not easily feasible given the old
wood, I would like to repair the tread.

Now removing the tread would not be easy since 2 balustrades are
toenailed into the other side of the tread and removing the entire
bannister and balustrades *seems* to me to be a big job.

So, I was thinking it might be easier for me to access the
underside of the tread from the alcove underneath the stairway by
cutting through the plaster and lathe on the underside of the
stairway. My idea would be to expose enough area so that I could
slip another board underneath the
tread to span the crack and add support.

To secure the support, my thought was to cover it with glue (either
polyurethane or epoxy). Assuming that I won't be able to get good
clamping pressure from below, I would run some temporary small
gauge screws through the face of the tread to temporarily clamp the
tread and support board together. Alternatively, I could try to
expose more of the stair underside at the risk of creating more
mess and a bigger plaster repair job.

Before, I go cutting into the plaster and lathe, I wanted to get
advice
on whether this is a good approach along with any additional advice
or pointers. Of course, I am open to *any* other better suggestions.

Thanks

I would glue the repair plate to the bottom of the cracked tread as
you suggested, and also secure it with screws just long enough to go
into the cracked tread, but not so long as to come thru the tread,
and leave the screws in permanently.
I was assuming that I would not have enough access room to screw in
the screws from below so that instead I would need to secure the
backer board by driving screws through the face of the tread from
above. In order to preserve the cosmetics of the tread, I was hoping
that once the glue set, I could remove the screws and at most have to
add a wee bit of woodfill to the holes left after removing the
screws. My thinking was that even if the underside of the tread is
not completely smooth or flat that epoxy or maybe construction
adhesive would hold the boards together securely after fully curing.

If the tread crack is 18 - 20 inches long in a tread that is
probably 30 - 44 inches wide, I would work in as big a piece of wood
as possible and not skimp on the screws. You may want to predrill
the holes in both the repair plate and the stair tread to prevent any
further cracking/ I think regular wood glue should be ok, it dries so
strong that a different part of the wood will crack before the glues
section will crack.
I was assuming that the underside of the tread may be rough so that a
more space-filling glue like epoxy or construction adhesive might be
better.

If you can get underneath to afix the sister tread, you can put screws in
place. Screws alone are perhaps 30% effective. Glue alone is perhaps 30%
effective. The two together are better than the sum of the parts. You can't
use too much glue nor too many screws.

As long as you're under there, consider reinforcing as many other steps as
you can reach. Someday some 300# fellow is going to walk up these stairs
carrying a 150# flat-screen TV...

Excellent (but scarey to think about) suggestion. On the other hand
since the understand of the stairway has a "curved" contour, I probably
will try not to rip out any more plaster than I absolutely have to which
means I at most will likely have access to the step above and below the
one in question...