Workshop: Advice wanted, and very much needed!

[Omnibuswoman]

Thank you all for your excellent contributions. I have now ordered the wood (a rather eye-watering £2400, but it is quite a big shed!) and have a couple of outstanding questions...

 

The timber store couldn't supply the 30 sheets of 2.4x1.2 11mm OSB 3 that I wanted. He said it is really hard to get hold of OSB at the moment, and offered me 9mm pine plywood sheets instead. Will these be adequate? Or should I go on a search of the south west for OSB?

 

I found this product at Wickes: 

 

Is this the correct product for the membrane between the stud and the cladding?

 

Insulation - looks like I will use mineral wool. Will 50mm depth suffice, or should I be stuffing the frame with 100mm? The workshop won't be an office or anything, I'm more interested in stopping it freezing over in winter and boiling in summer - it is basically a rather large shed. 

 

Many thanks!
 

 

 

 

[Cpd]

38 minutes ago, Omnibuswoman said:

The timber store couldn't supply the 30 sheets of 2.4x1.2 11mm OSB 3 that I wanted. He said it is really hard to get hold of OSB at the moment, and offered me 9mm pine plywood sheets instead

 I have not read this thread so excuse me if I have this wrong - rushing out of door - I would not use pine ply anywhere as it really attracts mould in my experience - got to go..... 

[Omnibuswoman]

I've managed to track down 30 sheets of OSB from a local builder's merchant. £25 a sheet plus VAT - almost £1k!! But I'd rather get it right and have the workshop outlive me than see it decay and feel that I could have done better. The chap from the BM said prices have doubled recently....?

[SimonD]

1 hour ago, Omnibuswoman said:

I've managed to track down 30 sheets of OSB from a local builder's merchant. £25 a sheet plus VAT - almost £1k!! But I'd rather get it right and have the workshop outlive me than see it decay and feel that I could have done better. The chap from the BM said prices have doubled recently....?

 

Yikes, that's expensive! But yes, OSB supply is a problem. Is the pine plywood you've been offered definitely a structural grade? Probably Elliottis pine if it is, I'd guess. The pine plywood should be fine for sheathing, it's been used for donkeys for sheathing. The only times you need to worry about mould is if the moisture content in the wood becomes too high, but then you're likely to get problems with the osb too. If your shed is built right, it'll be dry enough and ventilated enough so no need to worry.

 

Don't whatever you do put that vapour barrier you linked to above on the outside. You need a breather membrane. Your builders merchant should have something on the shelf that'll do the job.

 

I'd recommend you go for 100mm insulation at least.

 

HTH.

[Omnibuswoman]

Many thanks HTH. I have cancelled the OSB order and reordered the pine ply, which he assures me is structural, and is 60% of the cost of OSB. 

I have identified Tyvek as a popular breathable membrane choice, which seems it will do the job.  

 

Quick question: is it important not to have the insulation touching the ply or the membrane, or does it not matter?

Thanks!
M

[Marvin]

21 hours ago, Omnibuswoman said:

I'm more interested in stopping it freezing over in winter and boiling in summer - it is basically a rather large shed. 

Of course insulating a building doesn't stop it from freezing or boiling over if the outside conditions are extreme enough for long enough, it only slows the process down.

 

Pedants would point out various items that might make this not true all the time I'm sure.

[Marvin]

21 hours ago, Omnibuswoman said:

Tyvek

Tyvek good.

 

Personally I would fill the gaps in the stud wall with 100 fluffy.

Edited May 15, 2021 by Marvin

[TonyT]

What’s the wall and roof construction, that will determine the best insulation fit

cold roof/warm roof!

 

[Marvin]

This may help with discussions about part of frame and how to frame out for openings.

 

[Omnibuswoman]

2 hours ago, TonyT said:

What’s the wall and roof construction, that will determine the best insulation fit

cold roof/warm roof!

 

 

Walls are 45x95mm stud walls with 9mm ply on the inside, a breathable membrane outside, battens then shiplap cladding. 

 

45x110 depth rafters up to a central main beam (45x2200). 9mm Ply on top of the rafters, EDPM roof covering.

[Onoff]

3 minutes ago, Omnibuswoman said:

 

Walls are 45x95mm stud walls with 9mm ply on the inside, a breathable membrane outside, battens then shiplap cladding. 

 

45x110 depth rafters up to a central main beam (45x2200). 9mm Ply on top of the rafters, EDPM roof covering.

 

Any vcl in the wall makeup?

 

9mm on the roof will be crap to walk on even for maintenance. I've 12mm on one of my flat roofs (I didn't do it) and that's a bit springy even at 400mm centres.

[TonyT]

Agree 9mm on roof isn’t good.

best to double up if you have already bought it

[Onoff]

9mm on the roof might even sag over time and you'll end up with washing up bowl like depressions where the water will sit.

[SteamyTea]

Have you heard of a company called MacSalvors?

They are in Pool.

Always worth a call when you are stuck for stuff. And well worth a visit if you are in the area.

Pool is real Cornwall, not the nice picture postcard bit.

[SimonD]

20 hours ago, Onoff said:

 

Any vcl in the wall makeup?

 

9mm on the roof will be crap to walk on even for maintenance. I've 12mm on one of my flat roofs (I didn't do it) and that's a bit springy even at 400mm centres.

 

Ply doubles up as vcl in this buildup.

 

Agree with other comments re 9mm as the board for epdm. I'd suggest considering using the 9mm play on the inside of the roof (unless that's already planned) and then either doubling up as @TonyT suggests or getting in either osb or ply in 18mm.

[Onoff]

3 minutes ago, SimonD said:

Ply doubles up as vcl in this buildup.

 

With taped joints?

[SimonD]

26 minutes ago, Onoff said:

 

With taped joints?

Yes ?

[Omnibuswoman]

On 15/05/2021 at 16:46, Onoff said:

Any vcl in the wall makeup?

No, I got muddled between breathable membrane and VCL, so have gone with breathable membrane around the outside of the stud walls. 
 

Thanks for the advice about the roof. I’ll see if I can drop some of the ply from the order and get some OSB for the roof. 
 

This forum is worth its weight in gold!! I don’t know what I would do without your fantastic input!

Edited May 16, 2021 by Omnibuswoman

[Marvin]

Breathable membrane let's the moisture out of the studwork = outside side of the stud wall makeup.  

Plastic sheet stops moisture entering the studwork = inside side of the stud wall.

[Omnibuswoman]

5 hours ago, SteamyTea said:

Have you heard of a company called MacSalvors?

They are in Pool.

Always worth a call when you are stuck for stuff. And well worth a visit if you are in the area.

Pool is real Cornwall, not the nice picture postcard bit.

Down near Camborne! My boss (in London) is from Camborne. He comments on how people imagine Cornwall is just a county of pretty fishing villages with no rough bits, but there was an excellent TV programme featuring Camborne food bank a few months ago. Simon Reeves I think. It really highlighted rural poverty and social exclusion. 

[Omnibuswoman]

3 minutes ago, Marvin said:

Breathable membrane let's the moisture out of the studwork = outside side of the stud wall makeup.  

Plastic sheet stops moisture entering the studwork = inside side of the stud wall.

thank you. Should I put a layer of plastic sheeting between the ply and the stud, or just tape up the ply joins?

[Marvin]

Outside to inside:

Cladding

Batten

Tyvek

Thin ply

Studwork

Insulation and services in studwork.

Plastic sheeting 

Internal finish say plasterboard or ply or OSB.

 

There are discussions about the plastic required by building regs but not mandatory for sheds

[SteamyTea]

3 minutes ago, Omnibuswoman said:

Down near Camborne! My boss (in London) is from Camborne.

He will know, was he ex Holman's.

 

I used to know Don that run the food bank. Good bloke.

 

Camborne, Pool and Redruth was known as CPR, been renamed to Camborne, Redruth and Pool. CRAP.

There was a sign up for over a decade that said 'Pool is the Future'. It was modified a few days after installation to 'Poo is the Future' noone put it back. Just left it there for 10 years.

I think they will be bypassing the area when the G8 is one. They even put the Communication Centre in Falmouth, an hour from Cardis Bay. Heartlands is 20 minutes from there. But why show them one of the poorest places I Europe. Show them the vibrant, pretty but.

[Omnibuswoman]

10 minutes ago, SteamyTea said:

He will know, was he ex Holman's

No, he left Camborne for London in the early-mid 90s His mum was a local youth worker. His dad is a bat expert, so some of you may have come across him in the planning process!! His dad actually helped me out when I had a phone call from Cornwall Nature Police after a vindictive Neighbour tried to report me for “crimes against bats” when we had a hedge trimmed!! (The only bat nearby was in fact the Neighbour herself...)
 

I was deeply moved by Don - his hard work and compassion. He had just lost his wife when the programme was made. Incredible man! 
 

Where is the G8 being held? Scrub that - Carbis Bay! You did say that. Sorry!

Edited May 16, 2021 by Omnibuswoman

[SteamyTea]

13 minutes ago, Omnibuswoman said:

Where is the G8 being held? Scrub that - Carbis Bay! You did say that. Sorry!

It is sealed off like Royston Vasey at the moment. A camp has been built between PZ and Helston for the extra security staff, helicopters and extra police cars about. Almost like London after 7/7.

Drains and lampposts have been inspected and tagged, and the larger potholes in the A30 repaired.

Still wondering who is going to fly into Newquay, or Lands End International. Probably into the  Base at Culdrose. Except a plane crashed near there the other day.

I would have put them all at Lands End, then just cut that bit off from everyone. One road and two footpaths, easy. And plenty of space to land helicopters.

Edited May 16, 2021 by SteamyTea