Engineered joists do not require doubling up underneath stud walls, only the use of partition noggins. They look like they have been installed from the pictures. No herringbone struttting or solid strutting for I-beam Engineered joists are required either.
My guess would would be that the stud walls are fixed down to the floor using nails rather than screws. The slight (Permitted) deflection in the joist is causing a little friction on fixing between stud and chipboard. It is normal practice to use nail (paslode) fixing for stud walls however due to the nature of design for Engineered floors, nails really should not be used as the main cause for squeaks (annoying).
My guess would would be that the stud walls are fixed down to the floor using nails rather than screws. The slight (Permitted) deflection in the joist is causing a little friction on fixing between stud and chipboard. It is normal practice to use nail (paslode) fixing for stud walls however due to the nature of design for Engineered floors, nails really should not be used as the main cause for squeaks (annoying).
