Beefing up old staircase - best glue to bond ply to underside of treads and risers?

[Tim Watts]

Hey folks, long time no post. Sorry for the use of GG - don't have a USENET sub right now.

I have some old wooden stairs that are creaky and not very substantial. Figured I'd reinfrce them under tread with 18mm ply and battens onto the stringers *which are very substantial"

So the plan is to fit 18mm ply like this (excuse photo geometry, top tread and and batten are right, you'll have to imagine the rest):

I think it would be good to glue these in place to the underside and back of the treads/risers. I expect a reasonably close fit - old aged wood. Will use 4-6 fine screws to apply clamp force (4.5mm prob - don't want to split the old wood).

Do you reckon Titebond iii would be a decent glue for this application?

The battens will be glued and screwed with much more subtatial screws into the stringers.

I'll be able to get all bar the top couple of steps like this, which would be a huge improvement...

Cheers - Tim

[The Natural Philosopher]

PVA if surfaces smooth, low foam polyurethane if not

[Joe]

Eternal September is free and works nearly all the time.

[John Rumm]

Hi Tim,

Good to hear from you... Uncanny that some> Hey folks, long time no post. Sorry for the use of GG - don't have a

Eternal September seems to be working ok for me at the moment.

Are you still gluing that bungalow back together?

If it is a close fit, it will work well - especially if well screwed at regular intervals. You could use something like Titebond PU (or gorrilla PU) if there is a bit more variance - you get a limited amount of gap filling with the PU glues - but practically none with PVA/aliphatic resin glues.

You may well find you get adequate extra strength just from the ply if it is well fixed to the existing treads and risers. You can also hammer in the wedges a bit if they have shrunk with age to tighten it all up.

I would probably glue and screw the ply. Make sure the new riser is screwed to the back of the new tread (that transfers lots of stiffness to the tread). You can notch out to miss the existing arris blocks, or you can knock those off, and glue in new ones once the new "skins" are in place.

[Tim Watts]

Been busy - learning OpenStack, python, terrraform, ansible, git, CI/CD and all manner of other buzzwords for work :->>>

Oh cool - I'll give that a a try...

Yep!

Some things that have stood the test of time (10+ years in service) and ideas came from here: (Happy to go into more detail if anyone's interested)

Marmox tile insulation board under tile and engineered floors - been brilliant - no failures, helps on a cold floor.

F Ball Stopgap products and epoxy DPM - zero problems after levelling kitchen floor on damp subfloor.

Kahrs engineered flooring (that was The Natural Philosopher's suggestion iirc) - been brilliant. Takes damage gracefully - zero problems with gaps at joints.

Less brilliant: uPVC conservatory I had installed - forever chasing leaks. Taking spray foam to it soon! Oddly the uPVC windows I fitted myself have all been pretty decent.

I was wondering if to go with a PU instead. I'm fairly confident of a flat surface - the risers are currently (thin) ply and the treads seem OK. I'll run a steel rule over and check.

I will certainly do that - a couple of the riser wedges are missing too - should add new ones.

Oh - I had not thought to do that - will do.

Several have fallen off - probably not helping.

What is also not helping is being a fat bastard :->>>

That's for the tips John!

[John Rumm]

Yup I would be interested :-)

So tightbond and screws will do it - good sheer strength is what you need to properly add the extra depth of timber to the overall thickness in such a way that it behaves like a thicker plank rather than two thinner ones that can bend independently of each other.

The risers play a big part in the overall bendyness of the tread - the interface under the nosing supporting the front of the tread above, and the fixing to the back of the tread below adding stiffness to that.

I resemble that remark :-)

[Andrew]

Those stairs should take your weight without failing !

They look just like the ones that were fitted to most

1970's houses. What fails is the glue holding the wedges resulting in creaky stairs.

Since they are exposed (which the BCO would frown on because of the fire risk) you can apply a clamp force to the underside of the treads with a car scissor jack or two, and a collection of bits of timber to force the new timber plate up to the underside of the existing tread until the glue sets. Everbuild

502 seems to be faster than ?normal PVA.

The risers are always a bit of thin ply and in my house they are the cause of squeaks because the long slot at the front of a tread is unglued. Massively strengthening the treads might be all you need to do.

This is something I am considering at some point too. I did try and use those barrel bolts that tend to be used to hold wooden bed frames together to bind the lateral joint between a riser and the tread above that it slots into. Only partially successful though.

If any of the wedges have become loose then its more tricky because in order to reglue them all traces of the old glue must be removed. V difficult to do in situ.

Provided the treads are flat and clean then ordinary PVA will do. I use Everbuild 502. Really good stuff.

Andrew

[Animal]

Didn't make much sense of the diagram, but it looks overly complex. If applying ply or plank I'd cut it to fit under the tread, apply it under the tread & secure at each end/ riser with blocks of wood or little brackets of almost any sort. Pallet wood would do the job if you prefer, but with more end fixings as it's going to take 2 planks per step.

[Tim W]

And on - didn't realise ES was still going.

Excellent - plan in place!

Just need a new circular saw and track (the subject of another post).

Thanks again John - very useful info.

[Tim W]

It's just 2 bits of ply - one for the tread, one for the riser, repeated and beefed up with battens on the stringer.

Simplified edge view: