Workshop construction

[trevorbayliss]

I have been reading a couple of posts about workshop construction.

What do folk think of this for a plan starting outside:

Vertical larch
Horizontal 25x50 roof batons
Breathable membrane (tyvek etc)
125mm frame
100m full fill insulation in the frame
Poly sheeting
12mm ply finish

My main difference is that i am not using an external ply skin. I would prefer to have the ply on the inside so i can use it to screw/nail stuff into it. I don't want a plasterboard finish on the inside.

I don't need to meet any build regs for this.

 

[Fred61]

Yes your close. I build many timber buildings like this. Just a few pointers for you. You only need a 50x100 frame or as is now sold 47x95 regulated size. This is plenty sturdy enough. Yes the ply on the in side. Then a fill of 90mm celotex between the studs. As they are not 100mm timbers. Then cover the frame with tyvek or similar. Then you must fit a 25mm baton to each of the vertical studs to then fit your outer cladding to. This provides a very important air flow to your building that will help stop it rotting. Hope this helps. Fred.

 

[trevorbayliss]

Thanks Fred.

I have listed by 25mm baton, but i want them to go horizontal because i want to use a vertical larch board. Are you saying i need to add ANOTHER 25mm baton to the one i have put in.

The smaller frame is fine, but i can get 125 x 50mm treated timber for £1.80 per m inc vat. So this is a pretty good price. Plus i have a load of soft fill cavity insulation to use up and this is 100mm. I am not going over board on the insulation as just a workshop.

 

[Notch7]

If you want vertical boarding, you need to fit battens vertically onto the studs, then counterbatten horizontally. Otherwise there is no airflow.

You need insect mesh at the bottom over the cavity.

Tyvek housewrap is very good, although quite dear. You can also get the special tape which sticks very well.

I used 18mm osb3 on my shed, its not as strong as ply but quite waterproof so doesnt get spoilt during construction phase and 18mm thickness takes a screw well.

I didnt bother with a vapour barrier but used foil tape to join all the celetex together. Im always unsure on a polythene vapour barrier on an outbuilding because I cant decide if the inside of such a building is always the warm side which is the presumption to avoid condensation.

 

[Fred61]

That cross baton would work you need to ensure there is a air flow at the top. I would fit the top baton 4-6 inches down to let the air get round behind. If you can get a larger timber at the right price then great. soft fluff is fine but as I’m sure you know it’s got its limits. Hope it goes well for you. Fred.

 

[trevorbayliss]

Ah i understand now, the batons laid horizontally will stop airflow going in the bottom and top.

Ok, so maybe i will go for horizontal cedar.

Looking at the cromar pro product. It is 175g i think, so quite heavy compared to ones around 100g's.

The OSB isn't as nice to look at though is it. I want the ply to be a bit of a feature as well. Maybe oil it.

 

[Fred61]

If you go to your local builders merchant they will have a breather roofing felt at a much cheaper price. They will also have a wbp ply that looks nice you can’t oil ply as the oil will attack the glue that holds it together. You can use varnish.

 

[John D v2.0]

Vertical cladding is more tricky to detail, I read somewhere you should avoid horizontal surfaces on your cold side battens if possible. But slanted battens would be silly and I don't know who wants to rip and retreat battens at an angle! You're basically building a cold roof construction on its side, if that helps your thinking

 

[ban-all-sheds]

I don't need to meet any build regs for this.

Part P re safety and almost certainly ⃰ Part 12 re notification.



* Because if done properly, the electrics for a workshop will be notifiable.

 

[trevorbayliss]

Yes i have a sparky who will sign off the new fuse board. Just don't need regs for foundations, and the general build

 

[endecotp]

I would prefer to have the ply on the inside so i can use it to screw/nail stuff into it. I don't want a plasterboard finish on the inside.

Plasterboard has the advantage of not being flamable.

 

[John D v2.0]

If you want to fix into walls you can use that fancy plasterboard they keep advertising, alternatively use OSB or ply and then a layer of plasterboard on top.

 

[ban-all-sheds]

Just don't need regs for foundations, and the general build

I assumed that would be the case.

Yes i have a sparky who will sign off the new fuse board.

If you mean you are going to install it and then he is going to rock up, he can't honestly sign documents to say he did the work.