Pipe run query

[jaybeex2]

Im installing a new CH system from scratch, the query I have is regarding the routing of copper pipe. After going through a notch on a joist the pipes have to then run 'with the joists' for some 4m. My question is, do the pipes stay side by side horizontally with noggins between the joists for support or, do they drop down so they're side by side vertically so the can be clipped along the joist itself? Hope I've explained that ok.

Regards
JB

 

[denso13]

One above the other, clipped to the joist, is fine.

 

[footprints]

Whichever works out best for the situation, dropping down onto the side of the joist is fine if you are going down through the ceiling at the end, but no point if you have to come up again to run over more joists.