Water ingress from above patio windows.

stuart45

It looks like the tray is on top of the soldier course, especially as there is a slight break in the mortar bond. It's possible that the lintel has rusted enough to allow moisture through. I've seen older Catnic lintels rusted away in really exposed areas, although they were much older than yours. Even though they are galvanised, nowadays in exposed conditions they usually have extra protection like a tray. 
It's difficult to be really sure, without knowing the type of lintel used. If the simple things like repointing the soldier course and new sealant don't work, you will have to expose the lintel by removing a few bricks.

WIAWSNB

Thanks for the photos.

As Stuart has said, the lintel arrangement does appear to be unusual. The weep vents are seemingly in the 'wrong' place. (I say 'seemingly', 'cos I don't know). If they are 'wrong', then it would appear that either the cavity tray is mounted too high - in which case, what's holding up the soldier bricks?! - or else the cavity tray is correctly positioned, but the weep vents too high, so cannot drain!

I really don't know. It would need a builder or surveyor to determine.

This would theoretically be good news as it would be an 'obvious' cause (always good) and be very fixable, tho' requiring that section to be redone - surely an NHBC concern?

But, I don't know.

Q - do you have LP?

plumb1_2

In the last photo you can see the lintel is starting to corrode , and the mortar is crumbling away underneath the solider course.
My guess water is running down the brickwork and being sucked in(capillary action ) 
it all needs raking out and repointing including the solider bricks , plus remove the plastic bullnose trim.

When it’s all been raked out, I would clean any rust/ loose metal and paint it with galvanised paint before repointing.

stuart45

WIAWSNB said:

Thanks for the photos.

As Stuart has said, the lintel arrangement does appear to be unusual. The weep vents are seemingly in the 'wrong' place. (I say 'seemingly', 'cos I don't know). If they are 'wrong', then it would appear that either the cavity tray is mounted too high - in which case, what's holding up the soldier bricks?! - or else the cavity tray is correctly positioned, but the weep vents too high, so cannot drain!

I really don't know. It would need a builder or surveyor to determine.

This would theoretically be good news as it would be an 'obvious' cause (always good) and be very fixable, tho' requiring that section to be redone - surely an NHBC concern?

But, I don't know.

Q - do you have LP?

He does say that's it's not covered by the NHBC, although didn't say who provides the cover.
The problem seems to have started in the last couple of years, It's unusual to get a leak there nowadays, because apart from the tray, a Catnic lintel stops any moisture getting in. When Catnics first came out they were advertised as not needing a tray. It's only in really exposed areas where one is needed to protect the lintel. 
As that is such a long span, the lintel would normally be a Catnic CXL, or equivalent. A cheaper method could be a UB with a steel plate fixed to the bottom. 

WIAWSNB

stuart45 said:

He does say that's it's not covered by the NHBC, although didn't say who provides the cover.
The problem seems to have started in the last couple of years, It's unusual to get a leak there nowadays, because apart from the tray, a Catnic lintel stops any moisture getting in. When Catnics first came out they were advertised as not needing a tray. It's only in really exposed areas where one is needed to protect the lintel. 
As that is such a long span, the lintel would normally be a Catnic CXL, or equivalent. A cheaper method could be a UB with a steel plate fixed to the bottom. 

Ah, yes, he only said "I have contacted the insurance warranty company as the property is under 10 years old..."

It would be useful to know who they are.

What are your thoughts, Stuart? What construction arrangement is there? Why are the weeps so high up?

If the CWT is above the soldier course, could the miscreant gaps be as below?

stuart45

WIAWSNB said:

stuart45 said:

He does say that's it's not covered by the NHBC, although didn't say who provides the cover.
The problem seems to have started in the last couple of years, It's unusual to get a leak there nowadays, because apart from the tray, a Catnic lintel stops any moisture getting in. When Catnics first came out they were advertised as not needing a tray. It's only in really exposed areas where one is needed to protect the lintel. 
As that is such a long span, the lintel would normally be a Catnic CXL, or equivalent. A cheaper method could be a UB with a steel plate fixed to the bottom. 

Ah, yes, he only said "I have contacted the insurance warranty company as the property is under 10 years old..."

It would be useful to know who they are.

What are your thoughts, Stuart? What construction arrangement is there? Why are the weeps so high up?

If the CWT is above the soldier course, could the miscreant gaps be as below?

Water would penetrate where the yellow arrow is, although it shouldn't get past a Catnic. I don't know why the tray is over the soldiers. It should be like shown in the image.

Scottish_Dorset

Thanks everyone for your advice, it is very much appreciated.  I will be looking into the suggested options.  A builder, friend of a friend, suggested using this stuff.  He said he has used it for damp problems on several properties with success.  Is it too good to be true?  

Swipe

I'd go for Stormdry (which is breathable) over Permaseal and is good for 20 years. It completely solved the issues with my chimney.

stuart45

On an 8 year old house I'd want to know why there's moisture getting in first. You shouldn't have to resort to sealers. 

plumb1_2

stuart45 said:

On an 8 year old house I'd want to know why there's moisture getting in first. You shouldn't have to resort to sealers. 

That would be my call as well,