Pipe above ceiling or under floor?

[smudger]

Hi Folks
I'm installing a loo in a chaps back passage (fnaar!) which will have a boarded ceiling. He's had someone look at it and they suggested that the pipes should be taken from the kitchen below the ceiling and run across outdoor ceiling and drop into wc. The stopcock etc is by the external wall they will come through, so I'm inclined to come out there and run them under the floor (which will be tiled over). I guess my concern is with freezing pipes and ease of installation. Do any of you experts (which I'm not!) have any advice or tips from previous installations?
Thanks for your help & support,
Martin

 

[dontknowitall]

If you're suggesting putting pipes outside the building I'd say that's a no-no. It's so easy for them to freeze (even with protection) and you can easily end up with more, and possibly expensive, problems.

Putting pipes under the floor is fairly standard practice but make sure they're 100% leak free before laying the floor.

If you stand back and look at buildings they're pretty basic. Bricks, wall lining (plasterboard) or floor lining (floorboards) then the final finish - paint/tiles for walls and for the floor, wooden flooring/tiles or carpet. In the old days many wires and pipes (especially) were on show. Today we try to hide everything as it looks neater but, of course, that costs more money.

 

[smudger]

The back door opens into a covered passage (corrugated roof) and there is a small area that the guy want into a wc. The passage is outside of the house (outside external wall) and is not heated so both above ceiling and above ceiling will be pretty cold. I think the pipes are more likely to freeze in the space above roof as there is only the corrugated roof, but under floor will also be cold. My opinion is that they would be better under the floor (depth?) but a burst pipe under the tiles will create a lot more problems than one in the void above ceiling.

If I lay under floor what is the best to run the pipes in? Steel pipe or plastic conduit? And what's best way to insulate?

 

[dontknowitall]

You can buy a sort of foam insulation for pipes (two thicknesses - one normal and the other is DontKnowItAll thickness ...)

Whatever you decide, I'd fit isolation valves before it goes into this area so future maintenance is easier. If the ceiling is easier then you could use some extra insulation as well (rockwool type).

If I was being paid for this, I'd alert the customer to the potential of freezing and say that while I'm happy to do as much as possible to prevent this, I couldn't guarantee it wouldn't freeze.

 

[smudger]

Sounds like good advice, DKIA. Think I'll take the overhead option as easier to install and go for max insulation (but will warn customer as you suggest). If I did go underfloor, waht would you duct pipe in?

 

[dontknowitall]

Personally, I wouldn't duct as if there were problems later it could make it impossible to find a leak without tearing everything out. Another thing you can do (but I don't know the details) is have a heated wire running along the pipes which warms when the temperature is near freezing but this makes it more expensive to install and for an outside area is it worth it?