Big crack at top window reveal, potential cause? Can I fix it?

[homerenovationnoob]

Hello,

Background info: Roughly 1.5 years ago got uPVC windows replaced with new uPVC windows. House is 60s construction, likely originally timber frame. Exterior of window has row of soldier bricks and surveyor said likely no lintel. I am not sure when the crack appeared as it was covered by a blind, but doing some renovations noticed it today. I can't recall seeing it before or atleast not as bad, but cannot confirm that.

Today I noticed that there was a large horizontal crack on the top window reveal - photos attached. Material feels plasticy but inside is like plasterboard or something, not sure exactly what it is. I am wondering if its the brickwork on the exterior "coming down" causing the crack and a minor slope on the top of the reveal. The slope isn't massive but its noticeable, further down after where the crack is. Not sure if it was sloping originally when bought the house 2 years ago.

Can't see any obvious cracks outside or nearby inside. Trying to figure out if its the brickwork sagging down externally causing slope + eventual crack or what other causes, and potential remedies - ideally one I can DIY.

Photos:

 

[noseall]

Hello,

Background info: Roughly 1.5 years ago got uPVC windows replaced with new uPVC windows. House is 60s construction, likely originally timber frame. Exterior of window has row of soldier bricks and surveyor said likely no lintel. I am not sure when the crack appeared as it was covered by a blind, but doing some renovations noticed it today. I can't recall seeing it before or atleast not as bad, but cannot confirm that.

Today I noticed that there was a large horizontal crack on the top window reveal - photos attached. Material feels plasticy but inside is like plasterboard or something, not sure exactly what it is. I am wondering if its the brickwork on the exterior "coming down" causing the crack and a minor slope on the top of the reveal. The slope isn't massive but its noticeable, further down after where the crack is. Not sure if it was sloping originally when bought the house 2 years ago.

Can't see any obvious cracks outside or nearby inside. Trying to figure out if its the brickwork sagging down externally causing slope + eventual crack or what other causes, and potential remedies - ideally one I can DIY.

Photos:
View attachment 346645
View attachment 346644
View attachment 346643

Looks like a bit of slam movement, i.e. the door dynamics are causing the brickwork above to give a wee bit, because they are directly attached to the frame via silicone, foam, fixings etc.
Needs and angle steel or proprietary external steel lintel fitting. Remove the headers, prop with strongboys, fit the steel and re-lay the headers. Not a job for the faint hearted, especially the masonry.