Quote Originally Posted by devmonkey View Post
Sounds like a proper installation!

I can only suggest you pick up a laser and try it, or even just borrow a rotary laser from a local builder or window fitter.
Jazz will need something far more accurate than the cheap rubbish your typical builder will likely have.

My parents neighbour is a highly regarded surveyor, and has many tales to tell about builders and cheap kit. One was a job to do an independent inspection of a private swimming pool, which after being filled with water, had a 4" height difference between ends.
After a bit questioning, it came to light the builder had used a 'precision' laser to do the setting out, as lasers are "accurate" and less hassle than using a basic water level (aka a bit clear hose). Turned out his 'precision' laser was a special from Screwfix that had never been calibrated, but the builder was really pleased with it as it only cost him a couple hundred pound.
As the neighbour highlighted to him, it had just cost him far more than a couple hundred pound, as the whole swimming pool was going to have to be stripped out and redone.