Ply - non boaty.

[KevO]

Non boaty but prob best place for responses Son’s new house has a large shed in garden on a paving slabbed area with what looks like reasonable run off. All sides and roof seem very sound although a fresh coat of preservative will work wonders. Base is blo*dy chip board on 2x3” stringers which needs replacing. Plan is to lift shed off, rebuild a base on new stringers and remount shed etc. My ply of choice would have been 15 or 18 mm marine ply but expect he might baulk at cost - his first house and he is proud as punch and wants to do (pay) for everything himself although Dad labour and advice is always welcome. So, is marine ply overkill here? Would WBP/exterior ply from x supplier do the job if edges sealed with ‘poxy or similar? Is all WBP from usual ‘ town’ outlets gonna be a crap waste of time and money? Thoughts?

 

[KevinV]

Sheds go awful floppy without their bases, and are surprisingly heavy - if you can avoid lifting I definitely would, at all costs.

 

[DownWest]

Couple of us are building boats from exterior ply. 10mm standard sheet is around 60 euro. Not being too trusting, I boiled a bit and it is fine. Really surprising, no voids at all!
Peeps say, that economising on ply is a bad idea, but depends on what you can find. Good 'marine' here is well over three times the price.

 

[Norman_E]

WBP ply is quite suitable for a shed floor. I have bought WBP ply from both DIY stores and builders merchants in the past and there does not seem to be much difference, As said above the shed is likely to be far too heavy to lift if its a big one.

 

[Supertramp]

Exterior ply is good but avoid it getting continuously wet. Mount it on pressure treated timber - it's the bits in contact with the ground that stay wet. Even better to keep the wood off the ground with bricks/breeze blocks. Make sure it's anchored unless very sheltered. Marine ply is overkill. Unless the rest of the shed is marine ply......

 

[Blueboatman]

The main thing is airflow underneath
So stringers laid 90deg across treated timbers on the slab/blocks would be ideal for avoiding rot in flooring .
(Skinners sheds do just that and they last noticeably longer than stuff from the diy outlets )
You could use t and g boards or old floorboards too instead of osb/wbp plywood

 

[Boathook]

Both my sheds have tongue and groove floors mounted on stringers at right angles. I mounted the sheds on more stringers that in turn were on brick piles to make it all level. One shed is nearly 20 years old and the other 2 years old. The floor on the older one seems to be lasting better than the sides so far.

 

[pandos]

Why use ply, I would use treated decking or just plain pallet wood...

 

[aslabend]

I'd have thought OSB would have been the thing to use rather than ply.

 

[PCUK]

Buildbase supply the best Waterproof Bonded Ply (WBP). Personally I never boil ply! RGB is by far the worst. Delaminates as you pick it up.

 

[Rappey]

My shed is at least 35 yrs old, sat on bricks and has floorboards with 4-5mm gaps aiding ventilation.
Only thing ive had to do is refelt it twice so far, and use a wooden support pole inside to stop roof sag

 

[Jim@sea]

If you are using plywood for the base why not get a small sheet of Visqueen and fix it all round the plywood with drawing pins. That would add 20+ years to the life span.

 

[Rappey]

Sheds are fairly flexible so how about using a jack, lift and slide another pressure treated timber under the floor .
Im not sure if your suggesting the chipboard also needs replacing.
Why not use what ever sheet material is cheapest as it should not be getting wet . Sterling board /osb is quite common for shed floors.
Phenolic birch ply is by far the best ply ive ever used. Ive some offcuts in the garden that have had 8 years of weather on them and other than gone grey its still not gone soft.

 

[boomerangben]

My shed has T&G floor boards and no problems. Also if some of them did get wet and rot, I’d only have to replace some of the boards and not the whole floor

 

[38mess]

I used exterior ply on part of my boat deck. I epoxied over it and 5 years down the line it is still fine. It gets wet occasionally. Marine ply is £90 a sheet in Travis Perkins, and it's pot luck what quality you get.

 

[PCUK]

I used exterior ply on part of my boat deck. I epoxied over it and 5 years down the line it is still fine. It gets wet occasionally. Marine ply is £90 a sheet in Travis Perkins, and it's pot luck what quality you get.

Travis Perkins are another crap ply supplier and the 1088 mark now means nothing as it is used by any number of oriental ply manufacturers. I still reckon Buildbase can't be beaten, but then once encased in epoxy it doesn't really matter unless it is already delaminating when bought from the shop like the RGB stuff.

 

[38mess]

Travis Perkins are another crap ply supplier and the 1088 mark now means nothing as it is used by any number of oriental ply manufacturers. I still reckon Buildbase can't be beaten, but then once encased in epoxy it doesn't really matter unless it is already delaminating when bought from the shop like the RGB stuff.

A few years ago I had 3 sheets of 18mm marine ply from Travis Perkins to make seats for my boat. We threw the off cuts under the boat and the next day they were like Bananas totally delaminated.
It took almost 3 months to get them to agree a refund, and then they wanted to send another 3 sheets. But I got the replacements from browns in Bristol. 10 years later they are still sound.