First look for a leak.  If you find and stop it, the osb will dry out, and you are sorted.

90% chance it is a leak.

53 minutes ago, saveasteading said:

90% chance it is a leak.

My feeling as well.

Just what is leaking, an edge or a flat, badly laminated, surface.

We had a suspect leak in our Sika Trocal membrane, and the team turned up an electrical device where they wet the roof ( i think, cant remember if it needed to be wet or dry) and used a sort of electrical handheld roller to go over all the joins. Something about water 'leak route' making the electrical circuit which made leak finding pretty reliable & quick even on large roofs with lots of joints.

 

It was over a year ago so i cant remember the details, but I suggest a leak detecting specialist in your area would know of this tool & if it would work for you?

 

Telclad were the company we used & a helpful bunch, Lewis was our main guy who used the device...I only saw it for about 10mins before work, then we found the leak around a skylight through other means - not enough flashing and water was rushing don the roof & up the skylight and in.

 

 

20 hours ago, SteamyTea said:

Did you take pictures while it was being done?

It was raining 3 weeks ago, it's been wet for 5 weeks now.

@SteamyTea - thank you for your concern. Thinking about it, the GRP was laid about 4-5 weeks ago now (time flies when your having fun), so just as the wet weather imposed itself on Kernow. As you know it can be raining in the North and bone dry in the South of the county. We caught the dry(er) bit.

 

I did not take pictures. It was covered before hand. It was not raining when they laid and while it was curing, or when they painted. They did re-cover in between "sessions". Nosey neighbours do come in handy for such info 🙂 

 

That said, the guy was honest about some wet OSB board (where some rain seeped between overlapping plastic sheet) which was allowed to dry in the sun before they laid that couple of square metres (out of approx 200 sq m). I am keeping a very careful eye on what is happening. So far, all seems well apart from the two areas discussed in this thread.

Edited August 15, 20233 yr by BotusBuild

3 minutes ago, BotusBuild said:

the guy was honest about some wet OSB board which was allowed to dry in the sun before they laid that couple of square metres

Well that was good.

There are ways around the damp issue, but for that knowledge my palm has to be crossed with many pieces of silver.

3 minutes ago, SteamyTea said:

There are ways around the damp issue

So far, we have no evidence of that particular area being a problem, only the two parts by the outflows, but of course, time will tell

1 hour ago, BotusBuild said:

only the two parts by the outflows

Which is where the leak is....are the photos coming?

 

90% chance of a leak and 99% chance it is a joint at an outflow.

19 minutes ago, saveasteading said:

Which is where the leak is....are the photos coming?

 

90% chance of a leak and 99% chance it is a joint at an outflow.

5.5% chance is neither.

 

Apologies, I dont have photos yet, and now i've been called away to work (for 2 weeks)

UPDATE:

- I went up on the roof, swept and cleaned.. examined every inch of the GRP in pooling area especially along joints - no evidence of cracking or de-lamination

- I spoke with our supplier, he said typically its unlikely to be a leak, but he's happy to come back and inspect

His first thought was condensation and he asked what kind of building works we had recently carried out. I told him 65mm of liquid screed about 1 month ago!

We vented the house for a week during the drying process, but doors and windows closed since (we have air-tightness membrane 80% installed).
He advised to fully vent the house for a few weeks and monitor the situation.


I have taken a 120mm hole-saw and punched out the worst of the damp OSB and exposed the wet EPS to help drying.


 

On 15/08/2023 at 14:49, saveasteading said:

are the photos coming?

Away from site for 3 weeks, so not yet

wet EPS is a leak, its summer you shouldnt be getting tons of condensation anyway.

 

Alutrix as a VCL on the warm side, lapped down onto the internal walls. Insulation above (or up onto the parapet walls if you have upstand)and sealed with a weatherproof covering, EDPM far more forgiving than fibreglass.

 

Get the installers back to fix the leak.

15 minutes ago, Dave Jones said:

Get the installers back to fix the leak.

 

This is the obvious answer. I would leave it alone to allowing them to inspect it first. 

 

 

 

 

45 minutes ago, Dave Jones said:

wet EPS is a leak, its summer you shouldnt be getting tons of condensation anyway.

 

Alutrix as a VCL on the warm side, lapped down onto the internal walls. Insulation above (or up onto the parapet walls if you have upstand)and sealed with a weatherproof covering, EDPM far more forgiving than fibreglass.

 

Get the installers back to fix the leak.

Interesting

Does Alutrix have any 'self-healing' properties similar to bituminous nail tape?

Any VCL I put in is going to be riddled with screw-holes from the GRP fixings...

15 hours ago, westcoast said:

Interesting

Does Alutrix have any 'self-healing' properties similar to bituminous nail tape?

Any VCL I put in is going to be riddled with screw-holes from the GRP fixings...

 

another reason to ditch the stuff. yes it will take fixing from thermally broken mushrooms. You see a lot of bodges using various types of cheap plastic sheets that are not brought down the walls, all useless.

21 hours ago, Dave Jones said:

 

another reason to ditch the stuff. yes it will take fixing from thermally broken mushrooms. You see a lot of bodges using various types of cheap plastic sheets that are not brought down the walls, all useless.

Cool, I dont understand 'brought down the walls' though?

We have a parapet design, so surely if should be 'brought up the parapet wall' to keep condensation moisture within - like a big basin or swimming pool? 

At the edges of a flat roof the VCL should be continued up through the thickness of the insulation to join with the waterproof layer.

Harebrained idea #43:

 

We’re having an extremely dry September so I’m trying to dry out the roof as much as possible with dehumidifier.

 

The plan is to block scupper drain and fill the roof with about an inch of water and add a tracing dye.

 

 

Interestingly I cut some of the EPS out and found it to be dry higher up away from OSB..

On 19/08/2023 at 08:02, westcoast said:

Cool, I dont understand 'brought down the walls' though?

We have a parapet design, so surely if should be 'brought up the parapet wall' to keep condensation moisture within - like a big basin or swimming pool? 

 

run the alutrix up and over the parapet.  like this