Fixing rotten plywood

[Screwdriver]

Yeah, "go and buy a new sheet". OK you can go. I have a decent hoard of plywood in reasonable condition and rather than ***** fifty quid on a sheet only to cut it in half, I need to fix this one.

I have to keep it to length so I can't trim it off. What's the best way to patch it up before I use it outside as the permanent roof/worktop for my storage bunker?

I will post a pic (in a few minutes when I go back out) but it is about six inches along the edge, slightly rippled and delaminated probably 2-3 inches deep. I am thinking dry it out (??), fill with wood glue, clamp in between plastic sheeting and paint. I have various glues including exterior PVA and Gorilla glue (PVA). Epoxy is an option as is cascamite, just wondering what the best way to do it is.

Another option perhaps further down the road is to cover it with some aluminium lorry siding. I only hesitate because while I have a decent amount, I kinda want to save it for <something else>. It will be outside in a workspace so ideally whatever I cover it wth, paint, ally, EPDM etc. also need to function as a worktop. That's for the other thread really but it might influence how I repair this small section.

Does anyone know what they use in the manufacture of plywood? Perhaps that would be the best option??

 

[Onoff]

There's obviously different grades of ply. From crap up to marine grade. Any markings on it or little labels as to what it was?

 

[Keith 66]

If its started delaminating nothing will stop it, squirt any waterproof glue in there & clamp it up.
Real plywood used to be made with phenolic glues, todays far eastern stuff often appears to be stuck together with wallpaper paste!

 

[eLuSiVeMiTe]

Glue it up as best you can. Cover it in blackjack and felt it up

 

[gaz1]

I have to keep it to length so I can't trim it off. What's the best way to patch it up before I use it outside as the permanent roof/worktop for my storage bunker?

I will post a pic (in a few minutes when I go back out) but it is about six inches along the edge, slightly rippled and delaminated probably 2-3 inches deep. I am thinking dry it out (??), fill with wood glue, clamp in between plastic sheeting and paint. I have various glues including exterior PVA and Gorilla glue (PVA). Epoxy is an option as is cascamite, just wondering what the best way to do it is.

cut it at 8-10" hopefully you catch all the bad stuff

glue it upside down so the glue runs into the edges deeper then paint or treat it

once starts delaminating its trim until you can get back to a good edge then

reads as you have hoarding boards that delaminate fast but some plyboard also does the same prefer osb myself

 

[Screwdriver]

On the face of it, not too bad.

It has one bad section:

I am leaning towards flooding it with ext. grade PVA and clamping thanks all. Another issue is lots of screw holes. Filler? Silicone? PVA and wood fibre? Maybe an ideal use for that expanding Gorilla stuff?? It will get several thick coats of paint at least.

 

[Hitch]

I'd vote sand off and lose bits, cover with a generous coat of blackjack and put some felt over it and forget it.

 

[Screwdriver]

I'd vote sand off and lose bits, cover with a generous coat of blackjack and put some felt over it and forget it.

Yes thanks. If it was a roof, I'd tar it up no worries but it's also going to be a makeshift workbench, it is a horizontal space after all.

If I had stuck to the plan and cut it to 600mm, I'd have a perfect solution because I happen to have an old steel bike lift top that is 620 x 2500; that could have dropped onto it like a steel cap. But I made it 660 wide to give myself some wiggle room and an overhang. I may bite the bullet and chop it down to 620mm and drop a steel sheet on it. Underneath it will be protected with paint, but if I drop a steel sheet over it, I guess I need to fully seal it to stop water wicking underneath.

Decision, decisions...

 

[James1979]

That gorilla stuff is PU - expanding foam without the expanding bit. Or foam bit But it’s the same base ingredient. Water activated.

I’ve used it to good effect on leather belt for a lathe drive belt and some wood. You have to follow the instructions and wet the surface otherwise it doesn’t work

 

[Keith 66]

It looks damp enough already.

 

[gt6s]

Dont be so flamin tight. Use that you will be fixing it again VERY SOON. Doubleing your work

 

[8ob]

600 × 451

 

[gaz1]

he cant even burn it due to the bad fumes in the glue

smokes like hell as well

so no good in a wood stove either

 

[W.olly]

Having done this a few times with exterior PVA on Epoxy resin ( Epoxy being the best ) pushed well into the lam`s then clamping firmly, not to over tight though does the trick. It needs to be perfectly dry though.

I done sheets and have lasted a few years once the edges were also sealed with same adhesive.

 

[daleyd]

he cant even burn it due to the bad fumes in the glue

smokes like hell as well

so no good in a wood stove either

Ah but are they really fumes

 

[tom2207]

2 pack epoxy , west systems , and ad 10 to 15 percent xylene to slow down the hardening ,,, wont work on wet wood but under 2 or 3 percent moisture it will take a couple of days to set in this wather ,,, keep feeding the wood with epoxy as it soaks in , in the summer you can go up to about 30% xylene to keep the hardening time slow ... ask any one whos owned a wooden boat , this is the same stuff thats sold for many hundreds of pounds under fancy names , and has to be specially imported from the states.

 

[W.olly]

2 pack epoxy , west systems , and ad 10 to 15 percent xylene to slow down the hardening ,,, wont work on wet wood but under 2 or 3 percent moisture it will take a couple of days to set in this wather ,,, keep feeding the wood with epoxy as it soaks in , in the summer you can go up to about 30% xylene to keep the hardening time slow ... ask any one whos owned a wooden boat , this is the same stuff thats sold for many hundreds of pounds under fancy names , and has to be specially imported from the states.

I use Styrene for this good stuff, and then thought, all this cost to repair is cheaper to buy new lol

 

[tom2207]

I use Styrene for this good stuff, and then thought, all this cost to repair is cheaper to buy new lol

on ply it is ,,, but mahogany over oak and triple diagonal changes the cost / effort equation a wee bit .

 

[Onoff]

With whatever you do can't you make the top removable from underneath? Then when something better comes along, change it.

 

[Screwdriver]

With whatever you do can't you make the top removable from underneath? Then when something better comes along, change it.

I guess or I could just plonk something else on top... (see other thread)

Meanwhile, this happened:

I can't recall exactly what I made the weird <thing> for but it came in handy for this. Just shoveled as much goop in there as possible.

...and @James1979 it did expand and it is foamy.

Looks terrible but is as smooth as a baby's bottom.

I'll sand it back and probably use some of that wood solidifier stuff. Forget the name but tripped over a tin of it earlier. Thin liquid resin (?) which soaks in and stabilises the wood. Dunno if it's good for ply. Soon find out.

Anyhow, we are done here, over to the main event....