Hairline horizontal cracks in plaster the widen throughout the day

[james.wrigh]

Recently moved into a converted bungalow and had the front room totally replastered however over the past few weeks I have noticed hairline cracks in the corners of the front window wall (marked in red) These cracks seem to become more evident throughout the day & in the mornings almost not visible
This is causing me some sleepless nights so reassurance or a possible course for these would be most grateful

 

[mrrusty]

Probably thermal movement. Big roof areas on a bungalow will mean material expansion as it warms up can be significant. It might even be the window. 2m wide. Coefficient thermal expansion of uPVC (is it a uPVC window?) is ~0.07mm/degree/m so 20 degree rise is 20x0.07x2 = 2.8mm If the window is tight in the wall it will be trying to force the walls apart every time it warms up.

 

[james.wrigh]

Thank you so much for your time in replying and yes a UPVC window.
Your reply does provide me with some comfort so thank you again
Presumably I have to live with these issues?
In essence this cracking wouldn’t cause you concern?

 

[mrrusty]

If it is thermal movement, then yes, probably not much you can do, but neither is it really a cause for great concern if they just stay as micro-cracks. Obviously if they progressively get wider and wider you'll have to think again.

I put a flat roof on a utility room once and didn't leave expansion gaps in the boards. As the roof expanded, it bent upwards and used to open up a 5mm gap along the ceiling/wall corner when the sun shone, and close up when it was cold....

 

[^woody^]

Horizontal cracks in that location are typically roof movement related. That's not to say its bad, as it may be thermal, not structural, but its still something to look into.

Des this happen on the opposite elevation? What's the conversion? Is that plaster or plasterboard? (sound hollow when tapped)

 

[james.wrigh]

It’s a converted chalet bungalow & that is new plaster, 2 months old perhaps

I can’t see anything like this on the opposite wall if that is what’s classed as the opposite elevation

If thermal do we have to simply live with it?

Will a proficient builder be able to tell me if thermal or structural?

 

[^woody^]

Is the wall behind new?

It may be that there is a different material on the wall behind, and that moves differently to the wall below the crack, hence thermal movement. And if so, is more of a quality issue as it could be prevented.

It's not really a builder's job to diagnose the causes of cracking or movement. Builders build, and I suspect would love to diagnose some remedial work for themselves to do.

Structural Engineers or competent surveyors (not an oxymoron) deal with the diagnosis.