ᐅ Insulation and trace heating for plastic water pipes

Hello,

I have set up an apartment above the garage. For this, I had to install a water pipe from the house. It is made of plastic (32mm) (1¼ inches) and buried in the ground at a depth of about 120 cm (47 inches). The problem is that the pipe freezes during winter. I believe it is the connection point where the pipe leaves the house and enters the garage that freezes. I insulated it using a plastic pipe filled with spray foam. I know that this is not proper insulation, and I apologize for my mistake. Now I want to do it correctly and am prepared to dig again if necessary.

The outlet from the house and the entrance into the garage are quite close to the exterior wall. In the photo, you can see the entrance to the garage. The wall at the back is the garage wall. The outlet from the house is similar.

My question is: what insulation material and thickness should I use? Should I install a heating cable as a precaution? If yes, which type—one with a thermostat or self-regulating? Which type is suitable for a plastic pipe?

Thanks in advance for the answers.

Best regards,
scxx72