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Mike.C

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Hi All,

I am about to clad the walls of my workshop with ply, but before i order it i have a couple of questions which i hope someone can help me with.

First of all the render on one of the outside walls of my workshop is a bit damp. It is a 2 storey workshop made of granite and part of this ground floor wall is below grade (you walk down 6 steps to the lower garden). I am going to get a pro in to sort this out, but as i am about to revamp the inside of the workshop i want to protect it now, just incase this problem comes back in the future.

At the moment there doesn't appear to be any damp on the inside of this wall, but as i am going to clad the walls in plywood is there any ply that resits damp? Or better still is there a plywood that resits damp and insulates at the same time?
I know that there is various plasterboards which do this job, but i really want to use ply as this affords me the luxury of being able to put a screw in where i want too, and not having to search for a stud.

Secondly, as i am going to need 40 8x4 sheets it is going to get a bit pricey, so would i get away with 12mm shuttering ply on 2x2 studding?

Regards

Mike.C
 
Hi Mike

Mike.C":3e70o1ei said:
As i am going to need 40 8x4 sheets it is going to get a bit pricey, so would i get away with 12mm shuttering ply on 2x2 studding?

It's not a single garage then. :roll:



Sorry, I can't help you much on the damp side.

I believe that the reason for using 18mm is more to do with strength when attaching things rather than for insulation.

I used 18mm damp-proof mdf on 2x2 studding. To save cutting ensure the centres are the same width as your insulation. You can then put the green Wickes damp proof sheeting between the insulation and the mdf.

Cheers
Neil
 
Mike I think you could have a slightly bigger problem than you think in that even if you could find a board that was completely impervious to moisture it would ultimately start to smell behind the board, and I mean SMELL.

What I would suggest is that you line the walls with builders paper and fix 2x1 tanalised roofing battens horizontally to the wall, Now fix 2x2 battens vertically at 400mm centres. Insulate between the 2x2 with Jablite (polystyrene sheet) or slab insulation, ensuring there is a good gap at the rear. Fix polythene vapour barrier and I would suggest you use flooring grade chipboard laid horizontally to line the walls.

The (possibly) tricky bit is that you need to provide through ventilation behind the insulation.

Unless the walls are running with water this will give you a bomb proof finish.
 
can he not paint the walls with a bitumen paint and paint the backs of the ply wood with the same ,if its a two storey workshop where will your tools be mike ,on the ground floor or the top floor.

frank
 
Hi All,

Thanks Neil i think i will go with 18mm on 3 of the walls anyway.

KeithS

Good news, i had someone around today and it seems that my only problem is the cement render itself and a leak in the guttering. Apparently the render up near the guttering is coming away from the wall, and when it rains a crack in the guttering is allowing the water to get down behind the cement, and as it rains a lot and that corner does not get much sun it looks like it is damp.
He said that it was a big mistake rendering over granite in the first place and that the best thing we could do was remove it.

He also had a look in the workshop and he said that there was no evidence of damp. He said (the same as you) that you cannot miss the smell.

Thanks very much for your suggestions.

Regards

Mike.C
 
Hi Frank,

Sorry i must have been writing mine as you posted yours.

I have my machines etc downstairs and the work bench, hand tools and finishing upstairs.

Regards

Mike.C
 
Your best bet might be to use 18mm oriented strand board, known as OSB or Sterling board (I believe). This is cheaper than ply and will take screws OK. Much used in the building trade where cost might be an issue. 40 sheets is plenty enough to negotiate a good deal from a trade supplier
John
 
Mike...
re your granite walls...
I know from bitter expreience that someplace in the building regs, there's something about having to leave a huge void between the granite and any stud wall behind it. The flat here is granite; I wanted to investigate some way of insulating the walls and was told flatly...... sorry.... no can do. Any insulation added to the air gap could cause a localised pocket of radon gas to build up; apparently granite off-gasses the stuff all the time. Be sure to allow for this, and add some vent blocks to the walls too..
 
Hi All,

John, excellent idea. Never having used OSB i didn't think that it would hold any weight, as in cupboards etc., but now that i know SWMBO will like the difference in price.

Mike, yes i have heard radon gas mentioned before but i don't know to much about it (in fact it seems that i don't know much about anything). I'll have to get in touch with the local council to see if they can give me any advice. They should know what they are talking about because every house in the area is made of granite.

The rooms in our house have wattle and daub plaster walls and the gap between the plaster and the granite is only about 11/2 to 2 inches , is this enough gap for this radon gas?

Thanks for your help

Regards

Mike.C
 
Mike, yes i have heard radon gas mentioned before but i don't know to much about it (in fact it seems that i don't know much about anything). I'll have to get in touch with the local council to see if they can give me any advice. They should know what they are talking about because every house in the area is made of granite.

The rooms in our house have wattle and daub plaster walls and the gap between the plaster and the granite is only about 11/2 to 2 inches , is this enough gap for this radon gas?

Mike..
I've spent the better part of the last hour browsing for info on this... plenty hits, but none of the official sites leap off the page with guidelines for what to do in a situation for this. Wayyyyyy confusing.. The one thing that did come over was that Radon is something you can't dismiss lightly... Apparently there's between 15-22,000 deaths per year caused by radon induced lung cancer.. That said, it seems that it's straight forward to deal with using approved gas proof barrier materials and proper ventilation of the air gaps in the walls.
Best bet would be to get in contact with your local city archetects dept, explain what you want to do and your proposed method. They should be able to advise if there are any glaring errors in your proposal. One thought that came to mind was the construction of a non load bearing stud wall to carry your OSB. Line the outside face of the studs with a plastic barrier, insulate inside the studs (cuts thermal lossed and helps with sound proofing), then sheet the inside of the studs..
I know it's a lot of additional farfing about, but it wouldn't encroach into the existing air gap between the block work and current plasterwork.
 
Hi Mike,

Thanks very much for taking the time to look for this info. I'll contact them and see what they say.

Cheers Mike

Regards

Mike.C
 

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