Wet/damp patches at side of patio doorframe

[McKendrigo]

Hi,

I got a new patio door fitted recently (June 2022) which I noticed has some dark patches along one edge inside (1st photo). The door and installation should be covered by a guarantee, but before I get the company out to take a look I wanted to get some advice about what might be causing this so I have a better idea of what the problem could be before speaking to them.

The PVC trims and seals indoors and outdoors all look okay to me. There's maybe one tiny bit where the the sealant has lifted a little away from the trim on the outside, it's hard to see in the photo but I marked it with an arrow on the 4th photo. Otherwise no obvious gaps or cracks.

The rendering on the outside has several hairline cracks in it (2nd and 3rd photos). That faces west, so will get hit by the prevailing wind and rain. From the colouring it looks a bit like it has been patched up in the past by the previous owners. That's my best guess at the source of the problem.

Are there other possible causes I should be aware of? I've heard cold spots and condensation causing problems like this, though I wouldn't guess that's the problem here, as I don't think the room suffers from bad condensation and the affected areas don't feel wet or damp (though I will keep an eye out for condensation there).

 

[chalkywhite]

Hi, I was about to ask similar qu but for older UPVC, the glass is always soaked on the inside with condensation and that leads to the surrounding walls having grey/black mould staining.
I was going to ask whether new UPVC would see less condensation, as the glass would not let as much cold air in and therefore lead the condensation to condense on the windows, but that might instead lead to mould elsewhere.
The rooms in question are ventilated, the heating is regularly on, and I even use those Aero 360 devices on the window sills, which do collect water, however the glass is still soaked