Rain soaking through paint and render?

[Johnboy54]

Hello to all.
I'm sort of grasping at straws here.
I erected a DIY conservatory 2 years ago.
It's built against an existing brick extension, rendered and painted with masonry paint.
No problems until a few weeks ago when rain came through a corner all the way down.
See photos.
Trouble is, I can see no sign of rain running from the roof or down the corner.
I've not been home much lately but each time I do the wallpaper has a stain radiating from the corner all the way down. It reaches a good 18 inches in.
I've pulled the paper back and the wall/render is wet.
I've resealed everything inside and out and still it happens.

Now I'm reduced to wondering if it's possible for the driving rain to penetrate the paint/render on the corner outside and spread through to the inside.
It was painted about 8 years ago but still looks perfect.
In desperation I was going to try some Thompsons water seal inside and out, but is it effective over masonry paint?

It's raining now. Not heavy but constant. Nothing showing on the inside.
Any thoughts?
Please?

Many thanks,
John

 

[Notch7]

Is it a lean to?

How did you seal between conservatory roof and wall?

Im guessing there is no vertical dpc cut into the wall behind where the upvc window frame abuts the wall?

 

[Johnboy54]

Thanks for the reply Notch7.

Yes it's a lean-to.

There's an aluminium section that is bolted through the fascia and through the first 2 width-way 7x3 ceiling joists. (Long expensive bolts!)
This is sealed all around with LMA silicone.
On top of and around the sides is 6 inch fascia board for added sealing. The board was siliconed all over the back before being screwed to the original fascia.
This added fascia was again sealed on all edges.
As I said there's nothing coming from anywhere along the insides around the top.

There's no dpc on the uprights.
It's two metal channels screwed to the wall at each end.
Any gaps I filled with expanding foam.
I siliconed over this top to bottom inside and out.
There's a plastic strip which clips on outside, which I again siliconed.
Just to be sure I put a wider plastic strip over this and siliconed again.

I'm as sure as I can be there is nowhere for rain to get in along the top and sides.
Plus I can't see any rain coming in.

This is why I wondered if it could get through the paint and render.
Your suggestion that it needed a horizontal dpc seems to say it does.
There was no mention of a dpc in the installation manual.
The pattern of the damp on the wallpaper seems to radiate away from the corner horizontally, which isn't too clear on the photos because it's drying out.

Just read a post about rain coming through render which you were involved with.
The guy who did it had done rendering and plastering all over this area for many years and was well known for the quality of his work.

He used SBR in the mix because I provided it. Gallons of it. I had a lot of rendering.

Thank you.

John

 

[Johnboy54]

Bit late but it took me a long time to figure out.
It was condensation!
Baffled, I eventually found the inside top ledge against the house was wet through and running down the corner.
Then, I had a light bulb moment.
We have a tall, bushy Umbrella plant in the opposite corner.
I noticed the condensation happened when my wife watered it.
I told her not to give it too much water.
I bought a portable air-condenser unit and the problem was solved.
Couldn't believe the amount of water that thing sucks out of the air in the conservatory.
regards, John

 

[Notch7]

Bit late but it took me a long time to figure out.
It was condensation!
Baffled, I eventually found the inside top ledge against the house was wet through and running down the corner.
Then, I had a light bulb moment.
We have a tall, bushy Umbrella plant in the opposite corner.
I noticed the condensation happened when my wife watered it.
I told her not to give it too much water.
I bought a portable air-condenser unit and the problem was solved.
Couldn't believe the amount of water that thing sucks out of the air in the conservatory.
regards, John

thanks for the update -condensation can be a real problem -look at old single glazed windows, they often rot on the inside as much as the outside.