Help - Damp patches in plastering on loft conversion roof - 2nd opinion

Hi Everyone - new to this forum, I'm hoping somebody can help me with my problem.

Damp patches/water marks apeared last year in my loft conversion. My roofer took a peak under the tiles and the insulation was saturated. So he took the roof off and installed new breathable insulation.

Fast forward 6 months and the patches are back, See pics. The roof has no damage or leaks.

He is suggesting two options -
stain block then paint and see how he goes or redo the lot and use moisture resistant boards as it’s in the attic.

He says the the roof can't breathe - so i'm not too sure about his thoughts.

Don't we need more ventilation (ventalation vents) if so what would you suggest? And will everything need replastering?

So condensation forming because of a lack of fresh air blowing through?

Watch this for information on subject...

damploft said:

Hi Everyone - new to this forum, I'm hoping somebody can help me with my problem.

Damp patches/water marks apeared last year in my loft conversion. My roofer took a peak under the tiles and the insulation was saturated. So he took the roof off and installed new breathable insulation.

Fast forward 6 months and the patches are back, See pics. The roof has no damage or leaks.

He is suggesting two options -
stain block then paint and see how he goes or redo the lot and use moisture resistant boards as it’s in the attic.

He says the the roof can't breathe - so i'm not too sure about his thoughts.

Don't we need more ventilation (ventalation vents) if so what would you suggest? And will everything need replastering?
View attachment 78674View attachment 78675View attachment 78676View attachment 78677

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So you let a roofer rip out the correctly speced insulation (celetex) and put in a breathable insulation. Where exactly does he think this moisture needs to breathe from? There should be a membrane between the insulation and the plasterboard, the only moisture that could possibly need to breathe out is the moisture in the timbers (usually minimal) and that shouldn't be able to appear on the inside of the structure.

Did you see what horse they rode in on? We could check it in our checkaturd account.

You ain’t gonna get the answers you want here it’s nothing to do with plastering as @essexandy said VCL behind plasterboard is as far as plastering trade gets with it. The other side of the insulation needs through ventilation in from eaves vents or vented soffits and flow up to ridge vents or high up tile vents allowing flow under the felt.
People often show pictures of wet plaster but it’s like showing a picture of a flooded front room but really pictures of the burst river banks are the ones that show where the problem originated rather than showing the symptoms. Put up some pictures of the roof from outside (ideally on a roofing forum maybees?)

Thanks so much…. I’ll do that

Here’s the invoice of the work he did

Take roofing materials off
put back with inch gap but should be 50 mm min
£4300 lol

damploft said:

Here’s the invoice of the work he did

Click to expand...

Ah so it was your description of his works that was wrong.
It sounds like he's done things to the correct spec. give or take.

Monkey Boy said:

Take roofing materials off
put back with inch gap but should be 50 mm min
£4300 lol

Click to expand...

Don't think I've ever seen a 50mm gap on any set of plans mate. Felt is supposed to have a 25mm sag between rafters if I remember correctly?
On top of that architects can't add up. Nine times out of ten the speced insulation is as deep as the roof timbers, give or take.
If there's moisture getting in from above it's my guess that there isn't a membrane. Of course foil backed board is supposed to do away with the need for a membrane, but in practice is rarely doing the job.