Solid Shed build,vapor barrier question

[yuzi87]

There's no lintel over the door opening.

You mean reinforced double header etc above where the door will be?........

No, not header. We're not American. When I said lintel, I meant lintel.

:lol: :lol: :lol:

 

[yuzi87]

For your next build leave the top plates off until the walls are up and put them on overlapping the corners. A touch stronger that way.

Pete

Ah good point!

 

[Inspector]

Given that you want double skins of OSB I propose you build as the others suggest to a point. OSB, insulation, vapour barrier, strapping, but at this point instead of siding put your outer OSB on, strap again and then the siding. No need for any additional membranes. Caulk and paint the inside of the OSB for better moisture resistance. Use long screws when you put the OSB on the outside that go through the strapping and deep into the studs. The downside is because you already have the walls up the siding will overhang the slab more. Upside is getting the more secure wall. With the advent of cordless tools like reciprocating saws and chainsaws crooks won't be slowed for long if they get past the electronics, so I don't know whether the extra OSB is worth it. Up to you though.

Pete

PS. Don't know why you guys don't like bigger roof overhangs to keep the rain off the walls? Also great place to hang wind chimes from.

 

[MikeG.]

No, Pete, you can't put a vapour barrier on the outside of a wall, unless you live somewhere very hot and intend air conditioning the building.

What do you mean by "strapping"?

 

[MikeG.]

No, not header. We're not American. When I said lintel, I meant lintel.

:lol: :lol: :lol:

And it's "vapour", not "vapor". :wink:

 

[Inspector]

Look once more Mike. I did write vapour. :wink:
Whoops. That wasn’t meant for me. Sorry.

Okay incorrectly wrote vapour barrier instead of breathable membrane. Here I would call it house wrap.

By strapping I mean narrow boards to create an airspace to vent and drain moisture and water between two surfaces.

Pete

 

[MikeG.]

Look once more Mike. I did write vapour. :wink:

You did, but our OP, who I quoted, didn't.

Okay incorrectly wrote vapour barrier instead of breathable membrane. Here I would call it house wrap.

That's a really important mistake! Pretty much the subject of this entire thread.....glad you corrected yourself.

By strapping I mean narrow boards to create an airspace to vent and drain moisture and water between two surfaces....

Thanks for that. They're counterbattens over here.

 

[yuzi87]

Given that you want double skins of OSB I propose you build as the others suggest to a point. OSB, insulation, vapour barrier, strapping, but at this point instead of siding put your outer OSB on, strap again and then the siding. No need for any additional membranes. Caulk and paint the inside of the OSB for better moisture resistance. Use long screws when you put the OSB on the outside that go through the strapping and deep into the studs. The downside is because you already have the walls up the siding will overhang the slab more. Upside is getting the more secure wall. With the advent of cordless tools like reciprocating saws and chainsaws crooks won't be slowed for long if they get past the electronics, so I don't know whether the extra OSB is worth it. Up to you though.

Pete

PS. Don't know why you guys don't like bigger roof overhangs to keep the rain off the walls? Also great place to hang wind chimes from.

I am just doing the one osb skin inside now.
I didnt have a larger overhang as the wood was 2.4m so i just went with that to save time and money

 

[yuzi87]

So should i raise this OSB roof up with some battons then?

 

[MikeG.]

Batons are what a conductor uses to conduct an orchestra. You mean battens.

I have no idea of your roof construction so I couldn't begin to comment on what you need to do to make it work. Is it a warm deck or a cold deck? What is your construction, inside to outside?

 

[yuzi87]

Batons are what a conductor uses to conduct an orchestra. You mean battens.

I have no idea of your roof construction so I couldn't begin to comment on what you need to do to make it work. Is it a warm deck or a cold deck? What is your construction, inside to outside?

It will be osb inside, pir insulation enough to leave 50mm void then breather and osb

 

[MikeG.]

So long as the 50mm void is open both ends (via insect mesh) then that's fine. Apart of course from the silly breather membrane location.

What is going on top to keep the water out?

 

[yuzi87]

So long as the 50mm void is open both ends (via insect mesh) then that's fine. Apart of course from the silly breather membrane location.

What is going on top to keep the water out?

What is wrong with breather location? On a traditional roof breather goes on rafters then battens then tiles. Except in this case its osb instead of tiles?

The osb will be covered in felt which i will wrap around the fascia

 

[MikeG.]

So long as the 50mm void is open both ends (via insect mesh) then that's fine. Apart of course from the silly breather membrane location.

What is going on top to keep the water out?

What is wrong with breather location?..........

You've already been told by Blackswanwood. Again, this is basic stuff. Tiles are vapour permeable (through the gaps), the void below them is ventilated, and they are spaced 25mm above the "breather" membrane. That is fundamentally different, indeed opposite, to what you have done with the OSB.

 

[yuzi87]

So long as the 50mm void is open both ends (via insect mesh) then that's fine. Apart of course from the silly breather membrane location.

What is going on top to keep the water out?

What is wrong with breather location?..........

You've already been told by Blackswanwood. Again, this is basic stuff. Tiles are vapour permeable (through the gaps), the void below them is ventilated, and they are spaced 25mm above the "breather" membrane. That is fundamentally different, indeed opposite, to what you have done with the OSB.

There are a lot of messages on here saying a lot of things! It might be basic to you with your years of shed building but its new to me so stop being condesending.

So should i raise the osb with 25mm battens or not? I notice there was no membrane on your shed diagram

 

[MikeG.]

Look, these things have been explained to you repeatedly in this thread. Telling you that is not being condescending, and is nothing to do with my years of experience. All the information you need is here in this thread, and in the threads I have linked you to. All you have to do is follow the advice you have been given. You are remarkably lucky that anyone is still helping you. You may want to note the comments made by our moderator early on in the thread, and note too the positivity of the other thread I linked you to, here. That's how 99% of threads go here, if people approach them with the right attitude.

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No, don't raise the OSB. Cut the membrane away from underneath. It is doing more harm than good.