How to fix internal wall hairline cracks

Hi, I'm in a 7 year old double brick house in Perth, moved in about 9 months ago, structural survey all good.

There are lots of hairline cracks on internal (plastered) walls and looking for the best way to fix.
When I accidently knocked into one wall, I noticed the plaster under the paint had a white powder texture when I rubbed my finger over it. Not sure if this is normal or not. I've not come across it before.
I get the impression the previous owner did a quick patch job and perhaps the finish was painted over too soon? Or a sealant missed out? Stabbing in the dark here!

I was thinking of filling in the (very faint) hairline cracks with spec, putting some kind of seal over the wall (what?), and then painting.
Alternatively, it seems I can also paint over with some kind of flexible paint that will fill and paint in the one go?

I did paint over one wall with paint, a couple of coats, and can now only see a few of the hairline cracks.
But as there is so many of them (a big house) was wanting a longer-lasting solution.

Sorry if this sounds a bit dense, have spent ages googling, and still unsure.

First you need to determine if it is structural movement or some issue with the materials and previous methods used.

That's why I posted here, for ideas on that question ... hoping that someone might have had a similar experience and/or have knowledge. The recent structural survey was all okay so I am guessing it was the materials used.
Has anyone any suggestions of what I can try to fix it up?
Thank you!

May be that the white set was applied to thin or was too wet? We have the same problem at our place. Filled with skim coat and repainted.

On a brick rendered wall with solid plaster finish the render/plaster will shrink as it cures.

If the rendered wall is painted too soon after being plastered then hair line cracks will appear everywhere looking like crazy paving (or like crocodile skin) .

When the wall is repainted these type of hair line cracks should disappear.

Plaster cracks that look like zigzags (following the brick mortar joints) are more likely to be due to structural movement.

When I built my first house (about 40 years ago) I was told not to apply the final coats of paint until 1 year after the walls were plastered. Only to initially apply a clean up coat of paint to seal the walls.

I ignored this advice and painted the house throughout immediately and sure enough all the walls looked like crazy paving after about a year.

After 2 years I repainted the whole house and the crazy paving hair line cracks disappeared and never returned.

Thank you for your replies.
I think I'll repaint and see how it goes.

At our old house we filled the cracks with shelleys no more gaps first, just spread it with my fingers and wiped excess with a damp cloth. It looked so good, we can't see the gaps anymore (our paint colour was same colour as the no more gaps) so didn't repaint.




Yikes! Totally deluded by the planning and building process

Hi Penpit
You will need to identify the causes of brick cracking unfortunately masonry walls in perth are not reinforced. More info & pics required
Where is it build,are the internal walls clay V or H cored, where are the cracks located, length & height of wall, etc,etc