Can I get away with a small section of exterior pipe below the drain cock?

[pedr0]

In order to route a 15mm water pipe out into my garden, it needs to first go down and under an obstacle in an inaccessible space before coming up to the height of the patio which is the first accessible point. In this case then, there'll be a short section of pipe (300mm) below the drain cock.

Is that liable to freeze and burst the pipe even if the rest of the pipework is drained?

 

[oldbuffer]

Yes, it is likely to freeze.

 

[pedr0]

Oh no. It gets even worse. I've just had a closer look at how the pipe emerges from the house.

Our tiled kitchen floor and the patio are at the same height to make it look like the kitchen floor just carries on outside through the sliding doors. The builder seems to have routed a speedfit pipe under the kitchen floor, then somehow out through the wall below floor level, and then it pops up just outside. I.e. the speedfit pipe comes up through the floor outside. It's actually hidden behind some cladding.

In this picture, the OSB is where the cladding goes. You can see the speedfit pipe coming out to the left where the bulider has just jimmied the bottom osb panel.



I managed to slide my phone in to get a photo looking directly down behind the OSB. This picture shows the speedfit coming out of the floor at the bottom of the cladding.


So now I have at least three problems:

1) How on earth do I route that speedfit out from behind the cladding?
2) Even if I do route it out, how am I ever going to be able to drain it sufficiently? because it emerges at floor level and I can't drain lower than that.
3) There's a concealed join somewhere because it's copper under the sink in the house where the pipe disappears under the floor, and it's speedfit when it emerges on the outside. Isn't that a recipe for disaster?

 

[oldbutnotdead]

1 Routing-can't tell what you're trying to achieve from pics/words.
2 Draining. Long as you get water out of the taps and other fittings and there's mostly air in the pipe you should be fine- if/when the water does freeze if it is free to expand along the pipe it is unlikely to burst the pipe. If you're really paranoid, put a drain point indoors where you can get at it and another access point outside (a T with a pushfit stopend on the dead leg would do). Come winter, open yr indoor drain cock, attach a cheap compressor to the dead leg, blow it out at 2 bar or so.
3 pipe isn't going to freeze indoors. Worry is if builder has buried pushfit or compression coupler in concrete or in an inaccessible void...