Non drip box sheeting

riddles · 28-04-2021 07:07PM #1

Hi
On a new shed with box sheeting lined with non drip membrane when it rains I notice the non drip membrane is slightly damp a few inches on the inside of the shed. Is the membrane that is on the outside over hang drawing the moisture in. Should I just cut off the membrane on the over hang that is exposed. Thx

Fine Cheers · 28-04-2021 07:27PM

I believe this is called wicking and one option is to remove the anti con membrane on the outside alright, how easy is it to peel off ? What length is the overhang ? Is the outside just getting wet from rain ?

riddles · 29-04-2021 06:41AM

Fine Cheers wrote: »

I believe this is called wicking and one option is to remove the anti con membrane on the outside alright, how easy is it to peel off ? What length is the overhang ? Is the outside just getting wet from rain ?

The over hang is two inches, not tried peeling it off but will give it ago. Thx
I found this guide - seems the edge should have been scored on installation https://www.roofingsheetsbyrhino.com/anti-condensation-roofing-sheets/

dubbrin · 08-01-2025 12:25PM

https://www.boards.ie/discussion/comment/117027604#Comment_117027604

Hey sorry for the thread resuscitation, but did pulling the last few inches of anti-drip lining off stop the water wicking up? Or did you try a different solution. I'm researching here now on the same issue. I've been told to put in foam fillers, but if the anti-drip is still there then it will continue to wick upwards. (Low pitch roof here, 15-20 degrees).

https://www.pistonheads.com/gassing/topic.asp?h=0&f=207&t=1905177

https://diy.stackexchange.com/questions/216039/how-to-fix-capillary-action-on-anti-condensation-coating-on-box-profile-steel-ro

blackbox · 08-01-2025 12:45PM

My understanding is that the membrane should route moisture (that would otherwise drip into the shed) out to the gutters.

If you cut it off, where will the drips go?

dubbrin · 08-01-2025 01:09PM

https://www.boards.ie/discussion/comment/123032703#Comment_123032703

My set up is different. The ridge, eaves and lower walls are not sealed so it's 'well ventilated'. It's single skin. The anti-drip lining on the bottom of the roof cladding stops condensation forming underneath and dripping down. The lining is fabric like, and prevents vapour condensing on the cold underneath of the roof box cladding. It's glued onto the inside face of the cladding. This is typical construction for the more agricultural spec of shed/garage. I've seen it working elsewhere and it's a proven construction method.

My issue is that there seems to be water wicking back from the dripping edge at both sides of the roof. Instead of all the water running off of the cladding and dropping into the gutter, an amount is catching on the edge, which has this anti-drip lining. It's then wicking back up through the anti drip lining and travelling the 8-10" to the nearset timber where it further saturates this timber. The low pitch of the roof would seem to help this process instead of a 40ish degree pitch letting the water fall off much quicker.

I think if I remove 4-6" of this anti drip lining it won't provide a way for water to travel back from the dripping edge. Interested to see how @riddles got on. Or maybe I have an issue with wind blowing it back as well. One step at a time anyway.

Non drip box sheeting

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