Ply is definitely stronger, but from a comfort perspective I would be worried about the acoustic performance for a painted finish. You will get a shrillness and much more echo than from Gib.
If you are planning on a painted/poly finish, it will be problematic trying to lose the joins. It would look better if each sheet edge is arrised so the panel exists in its own right. If you want a monolithic look, stick to well stopped Gib.
moltenfire,
May 25, 7:52am
What did u cover it with or did u paint it? How did u seal the joins?
I worked on some offices in canada lined with ply.Instead of butt joining sheets we had a 10mm metal negative detail insert. Stopped all the problems of cracking/finishing joints.
mm12345,
May 25, 9:24am
Malthoid behind the ply in the joins, plus corner flashings. Then H3 framing over the top of the old framing secured with batten screws, ripped to depth to line up the new cladding with the old foundation, 20mm cavity battens, then the cladding which is mixed 75mm poly/plaster, and linea. Had to install flashing systems into all existing joinery, flashings around perimeter foundation, remove and replace all sub-floor vents 25mm lower to allow for downturn on lower flashing, new scotia around all openings and soffit/cladding, replaster foundation etc. I subbied the cladding out, but did most of the rest myself - as I'm not an LBP, working "under supervision" of the LBPs I employed and working alongside them. They were all excellent. I could have stuck brick back on for a tiny fraction of the price - and without building consent (chch rules) - but that would have been nuts. It came out good - a far stronger, lighter, better insulated house than it ever was, but looks new/original - not "molested".
mm12345,
May 25, 9:41am
If you're concerned, reinforce the bearer tie downs to the perimeter foundation with galv angles, coach-screwed into bearers and 12mm concrete screws. I did this, as some of the old-style #8 wire tie downs failed as the vertical movement from the quake lifted the bearers off the foundation and pulled the staples out. I also fit 12kn straps to all pile/bearer connections, and fit galv bar through-bolted both sides to any joins in bearers. Not a big/expensive job - so long as you have access. I was going to cross-brace piles, but an engineer talked me out of it on the basis that it hadn't suffered any damage that cross bracing would have solved, despite having been subjected to forces about 10x what was ever expected - so should be fine, touch wood. My objective was to make the house survive the Alpine Fault quake, up to 5 min shaking at a pga of about 0.25g.
sooby,
May 25, 10:28am
Houses & bracing are designed to leave the house occupants alive after a big quake, that's all - if the house is buckled but you are alive it did it's job!
They act much like car airbags in that regard.
IMO if you are that concerned about it, sure lay ply - then gib over it to get a better finish.
zak410,
May 25, 10:28am
I think 12mm is overkill, better get 9mn good interior grade.
Agree with above about arrised edges, not trying to hide them, also definitely not having 2mm gap.
The size will be stable indoor, leave gaps in the corners for any possible movement.
**Ply could also be stopped, with paper tape for joints and skim coated surface if really required for better finish, providing it is sealed first**
jkp58,
May 29, 8:48am
You could do it with a 5 to 10mm gap like express joints.
masturbidder,
May 29, 9:17am
I used CD grade (with beading over the joints) in a bathroom and varnished it. Looks good. And good for screwing hooks straight on.
moltenfire,
May 30, 8:05am
Followup. Left a 2mm gap and ran the router thru to put a 45 degree edge on each sheet. Then filled with epoxy filler and flashed with belt sander. Suresealed over that and can't see any sign of the join. Time will tell though. it may be that expansion/contraction will reveal the joint although the epoxy/ply bond is pretty strong and my friends husband who builds boats reckons it will never split or show a crack. Just done one wall of 4 sheets (ie 3 joins) and will leave for a year before deciding to do the whole house.
goldywing,
Jun 6, 1:49am
Why not go with a fair face finished or blonded ply with a larger gap between sheets.In fancy terms this is called something like "negative detailing". and dont forget to aris the edges
coop19,
Jun 6, 7:21am
I have built the odd plywood boat using epoxy fillers and paint to a high gloss finish. Never had any cracks or flexing movement noticed. Mind you bracing behind the ply in boats tends to be much closer together than in home wall construction for obvious reasons. And again the marine grade ply of course is a superior product to construction ply or similar and much more expensive.
fordcrzy,
Dec 21, 9:18am
why not use 10mm MDF? much smoother and straighter. i find ply ALWAYS warps between studs and you never end up with a truely straight wall as with gib or mdf
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