Is this normal - drip marks on breather membrane in new roof

[Cellophaneskies]

Hi all

End terrace house had new roof (tiles, battens, membrane) within the last two years).

It’s been rainy gently the last couple of days - no high winds or driving rain - and I see little tiny marks on the breather membrane like wet spots or trickles. These marks were not here a week ago when we last came up into the loft!

They don’t seem to appear where the membrane is overlapped which suggests to me it’s coming from above.

To me, tiles should be taking aaay all water from rain and the membrane is there is an utter last resort in the case of extreme weather but opinions online vary about this. Some say it’s normal. Some say you shouldn’t be seeing it at all.

Looking for more opinions here. My instinct is that I should be seeing this. Roof pitch is quite low but appears to me like the tiles have sufficient overlap etc from the specs I can see online.

 

[catlad]

Photos

 

[noseall]

Hi all

End terrace house had new roof (tiles, battens, membrane) within the last two years).

It’s been rainy gently the last couple of days - no high winds or driving rain - and I see little tiny marks on the breather membrane like wet spots or trickles. These marks were not here a week ago when we last came up into the loft!

They don’t seem to appear where the membrane is overlapped which suggests to me it’s coming from above.

To me, tiles should be taking aaay all water from rain and the membrane is there is an utter last resort in the case of extreme weather but opinions online vary about this. Some say it’s normal. Some say you shouldn’t be seeing it at all.

Looking for more opinions here. My instinct is that I should be seeing this. Roof pitch is quite low but appears to me like the tiles have sufficient overlap etc from the specs I can see online.

Yes it's normal for a building (especially a recent build) with high humidity. We always supplement our breather membrane with OFV's and vented ridge.

 

[Harry Bloomfield]

They don’t seem to appear where the membrane is overlapped which suggests to me it’s coming from above.

Might it be condensation, of moisture, from below in the house itself? It has been a cold week, a few frosts, if the loft hatch has been opened...

It also might be due to inadequate ventilation of the loft.

 

[Cellophaneskies]

Example photo here. Little spots like drops have hit the membrane from above? Have this in a few places. Some are longer, like a drop has run along the membrane.

Unsure if it’s condensation. I am going to look to add some more ventilation to the loft. They seem to be more numerous after rain which is why I didn’t think they were condensation initially.

 

[Harry Bloomfield]

In your photo, it looks like rain penetration, through the roof tiles. Post some photos of the roof, and tiling, from the outside, one of the experts on here, will be able to give an opinion.

 

[Koolpc]

In your photo, it looks like rain penetration, through the roof tiles. Post some photos of the roof, and tiling, from the outside, one of the experts on here, will be able to give an opinion.

I agree

 

[freddiemercurystwin]

The membrane should be draped rather than pulled tight, so that anything getting past the tiles can drain down the membrane rather than getting stuck where it meets the batten.

 

[Cellophaneskies]

Argh. I somehow don’t have any photos to hand. I’ll have a look through. Could there be condensation on the underside of the tiles that then drips - is that something that could/does happen?

Tiles are concrete square ones, flat, interlocking. Theres about 7cm of headlap on where they lay over each other.

 

[Cellophaneskies]

I had loads of photos but I must have deleted them! I only have a snip of a section from another photo. The roof looks like this all over - it’s all very uniform and straight and square. Imagine this.. covering an entire roof. I know it’s not an ideal image.. I’ll get some better photos tomorrow.

 

[Harry Bloomfield]

Argh. I somehow don’t have any photos to hand. I’ll have a look through. Could there be condensation on the underside of the tiles that then drips - is that something that could/does happen?

I would suggest, yes. Especially in the weather we've had recently, very cold, and warm. Very cold tiles, the weather warms up, then moisture condenses out from the outside and the inside of the loft.

Everything large and metal, inside my workshop the other day, was covered with condensed moisture.

 

[AlexBoy071]

In your photo, it looks like rain penetration, through the roof tiles. Post some photos of the roof, and tiling, from the outside, one of the experts on here, will be able to give an opinion.

Out of interest (to a very new first-homeowner) is this something to be concerned with? Similar tiny dots on my 2017-build.

 

[Cellophaneskies]

Out of interest (to a very new first-homeowner) is this something to be concerned with? Similar tiny dots on my 2017-build.

As an update these disappeared in summer so they must have been dampness. Suspect condensation