breathable membrane over or under roof battens

[fourteen0407]

hi all,

can anyone please advise me if this the correct way or whether this will cause problems later.

i am making a pithed roof and have got to the part where i need to lay the breathable membrane, only thing is i have already fixed the roof battens and now want to lay the membrane over the top of battens and then fixed tiles on top.

they are standard vangaurd 83 interlocking roof tiles that will sit ontop of the membrane once its laid along battens.

i know now the membrane should go under the battens but ive fixed battens now. so can i carry on the fix tiles now or does all battens need to be ripped up.

thanks
Margaret

 

[^woody^]

 

[fourteen0407]

sorry what does this mean

 

[Laggy]

Seriously tearing up over that perfect gif

 

[Laggy]

OP, I am an inexperienced DIYer and I thought the description sounded bad then when I saw Woodys gif I thought oh it isn’t some fancy new method then

 

[fourteen0407]

so the membrane has to go under, as some sites suggest it can go on top

 

[^woody^]

as some sites suggest it can go on top

Really? Are you sure these weren't Australian sites?

Got any links?

 

[fourteen0407]

breather over or under counter batten - Green Building Forum
http://www.greenbuildingforum.co.uk ›

 

[fourteen0407]

i would appreciate it if you could advise me and explain if i left it like this, why this would be a problem

 

[Notch7]

breather over or under counter batten - Green Building Forum
http://www.greenbuildingforum.co.uk ›

That isn't the same scenario as yours.

They talk about counter battens.

 

[^woody^]

i would appreciate it if you could advise me and explain if i left it like this, why this would be a problem

That link is apparently describing a counter-battened roof. Yours is not.

This is counter-battening, and the membrane could be fitted above or below the counter-battens (bottom ones), but not above the battens (top ones)

 

[stuart45]

A counter batten is different to the battens. It runs with the rafters, not across them. The membrane need some slack to fall into the gap between the rafters to allow any moisture to run down to the bottom and away. The way yours is done won't allow this.

 

[Notch7]

i would appreciate it if you could advise me and explain if i left it like this, why this would be a problem

It looks like you are building a conventional cold roof with an air gap directly below the tiles.

With such a construction detail the breathable membrane is unsupported - and any rain water getting under the tiles will pool on the membrane and can't escape.

Same issue with condensation.

I'm sorry but your best bet is to remove the battens.

As far as I know breathable membrane never s goes over tile battens, it may however go over counterbattens which run in line with rafters.

Edit: Woody posted whilst I was typing - see pic
Edit: and so did Stuart45!

 

[fourteen0407]

Ok i understand. Thankyou all for you help and advise. Looks like all the battens are coming up. Any advise how to take them up without snapping them or breaking. They each are 3.4m in lenght

 

[stuart45]

Did you use ring shank nails?