Tim Lamb wrote:

Andy Burns writes:

With all them 'oles in the metal web, why would you even want to cut slots?

Wet underfloor heating (Speedfit) uses aluminium spreader plates nailed
to the joist tops with the pipe run trapped in pre-formed channels. The
pipe has to go through or over the joist to reach the next joist pair.
Going through involves a lot of pipe threading.....

OK, I see. JG seem to recommend fixing the plates to the bottom of the
flooring when using engineered joists rather than to the top of the
joists ...

https://www.youtube.com/watch?v=gx2jEz3bfkk