I would hire a structural engineer to come look and make a report with recommended ways to repair this. You might want to get a second opinion too. Once you have that information, submit it to your builder, in writing, telling him what repairs you expect him to do to fix the problem.

If you builder refuses, then get a lawyer involved.

I'd get a caulk gun before an attorney. Much better odds of winning and much less expensive.

If you're in B.C., Alberta, Ontario or P.Q, your home should be covered for structural defects by mandatory provincial programmes. However, minor settling and truss uplift cracking is unlikely to be covered unless it is a sign of a structural defect.

In Ontario, cracks in excess of 4mm would, however, be required to be repaired. See below.

But Alberta's Construction Performance Guide appears to take a stricter stand:

However, it doesn't cost you to file for an inspection and claim.

Here's an excellent guide to avoiding and disguising truss uplift in new home builds.

One crackup definitely not covered!

(When I was an Ontario licensed builder, I did only stick framing--except for one where the client's architectural technologist speced trusses to save a buck.)

Latex caulk is a good way to fill these gaps. Spread a bead of caulk along the gap with a caulk gun. Smooth the caulk with your finger and let the caulk dry overnight.

We had many cracks like this when we built on 2018. Our builder and his team came in several times to correct it within the first Year of us living here and lots of it was settling I believe. Other than some unrelated issues with painting all the cracks stopped by one year mostly. We are in BC Canada and had no problems with getting this part fixed by builder. Other deficiencies were a headache big time. My big tip to you is to go through your new hoMe warranty and start a claim. If you don’t do this within the first year then it’s too late down the road and won’t be accepted

Now when people ask you how you like your home you can tell them it is up-lifting.

Just like a truss for inguinal hernias!