New workshop insulation??

[martyn55]

Hi can anyone help, i am building a workshop at the end of my garden and am unsure how to properly insulate it,
I am using 95x45 treated timber for the framing and was going to clad the outside with 11mm osb covered in breathable membrane then clad straight over the top with 16mm shiplap cladding, then on the inside fill walls with 100mm insulation slabs and then finish off with 18mm osb, then basically the same for the roof apart from covering it with corrugated roofing sheets .
I am concerned about condensation build up in the walls and roof space, do i need to vent the roof ,leave gaps ect or add vapour barrier to the walls ,
I could really do with some expert advice as the is so much mixed information out there as i am a bit lost ??????

Thanks Martyn.

 

[Lons]

Do a quick search on the forum Martyn as there are absolutely loads of posts on the subject which should answer your questions

Bob

ps welcome btw - it's a great forum with some excellent members

 

[Peter Sefton]

I am no expert in this but from my own experience I would add a 25mm baton on the outside before fitting the shiplap to form an air gap, possibly fit a DPM on the inside to stop moisture from the workshop entering the studwork and trapping dampness forming rot. Have a plasterboard finish on the inside to kill both sound and fire spread.
Sounds like fun Cheers Peter

 

[longinthetooth]

Vapour barrier inboard of framing & insulation to prevent moisture from the inside air entering wall structure where it will migrate towards the outside & condense in cold outdoor conditions. This can be a sheet of polythene. Lap & tape the joins.

Cladding needs venting behind. Use 25mm battens.

Similarly the roof. There are many options but that's a basic scheme.

 

[WoodMangler]

Have a plasterboard finish on the inside to kill both sound and fire spread.

I lined mine with 1/2" ply, fireproofed with 'Flametect' and coated with white emulsion, and I surface-mounted all the electrics. This means that I can attach shelves, brackets etc to any part of the inside walls, move and add to the electrical sockets as I need, and drill holes without having to worry about hitting hidden wiring. It costs a bit more than plasterboard, but I think it's worth it overall.

 

[Peter Sefton]

Have a plasterboard finish on the inside to kill both sound and fire spread.

I lined mine with 1/2" ply, fireproofed with 'Flametect' and coated with white emulsion, and I surface-mounted all the electrics. This means that I can attach shelves, brackets etc to any part of the inside walls, move and add to the electrical sockets as I need, and drill holes without having to worry about hitting hidden wiring. It costs a bit more than plasterboard, but I think it's worth it overall.

Sounds like a good plan

 

[martyn55]

Thanks for all the advice, plasterboard sounds like a better idea than osb and cheaper.
Does anyone know if i can use regular roofing breathable membrane on the outside walls or do i need what they call housewrap which sounds like the same thing to me, also im trying to find out if the roof needs to be vented from the inside in any way as it has no loft space just rafters connecting to a ridge board and insulated between ??????

All help much appreciated

Martyn

 

[Peter Sefton]

As I understand it the roof and wall membranes are much the same, roof possibly more expensive but if you have got one roll I would use it for both.
Cheers peter

 

[martyn55]

ok thanks i thought that might be the case ,

Much appreciated

Martyn

 

[martyn55]

Hi, i am still a little confused over whether i need to vent the roof space between the insulation and the osb and have soffit vents, since i am having no roof space i thought a vent high in the roof either end of the building would be sufficient the let air flow through and if i am using a vapour barrier on the inside would there be any need to vent the roof space ??
Help !

Thanks Martyn.

 

[cammy9r]

Hi, is it a pitched or flat roof, the method is the same really as long as air can flow one side to other.
The roof should be from top to bottom -
Tin sheathing fixed to counter battens
breather membrane or underlay felt
In Scotland we tend to put in another layer of osb3 or sarking boards
min 50mm air gap with continuous, meshed air gap at both eaves 10-20mm wide
insulation
vapour barrier ( I left this part out as I used painted osb, but for the extra £30 maybe I should have put it in)
plasterboard or osb
I used Permavent Eco as a house wrap around my shed and on roof it was not expensive, say £70 for 100m x 1m.