Speedfit "loose" under floors

[Pete Verdon]

I want to lay some 22mm speedfit (the coiled kind) from one location upstairs to another. This needs to pass under a room whose floor I really want to avoid taking up. Fortunately, the joists run parallel to the direction I want to go (I can see them in a cupboard downstairs where the ceiling has been omitted). It should be practical to run the pipe in at one end and push it all the way to the other, running between a pair of joists. I could probably clip it into place at both of those ends. But in between, a distance of maybe 3-4 metres, it would be floating loose. Is this permissible, or a horrible bodge? I've never worked with Speedfit before.

The house is of conventional early-90s construction.

Pete

[Pete Verdon]

Actually, having just been and poked a webcam onna stick into it, it isn't. There are some cross-pieces between the joists (noggins?) in the way. Bum.

Still, a lesser form of the question applies - how thoroughly does one generally need to fasten speedfit in place in areas that are out of sight?

Pete

[RubberBiker]

From memory, the manufacturer recommended horizontal distance between clips is about 400mm. In practice, with mains pressure *cold* water, and jointless, I don't it would make any difference. Hot pipes will sag quite a lot within days/weeks - this may give you airlocks at high- points, if low pressure.

Comprehensive guidance in a pdf on their website:

it be possible to clip a section of pipe to a backing board, and slide that into the void, and then screw it to a joist?

[Pete Verdon]

As I said, the under-the-floor plan is on hold anyway, until I take the kitchen ceiling down (which is planned eventually) in which case I can clip at the recommended distances. I am now just wondering how fully I need to clip things in place inside my bathroom false wall.

Pete

[jim]

but if it's lying on top of ceiling sagging shouldn't be an issue.... assuming hot water is at worst an upstairs cylinder don;t think airlocks will be problem either.. I'd just shove it through and forget the clips that are beyond reach.

cheers jim