w/c pan fixing points directly over c/h 22mm flow and return pipes.

[TerryH]

The subject line says it all!
The new close coupled pan/cistern I have to fit has its fixing holes directly over the main 22mm c/h pipes. I'd have to pack the cistern off by about 30 mm. to clear the pipes.
I'll fix with some short screws that don't penetrate the flooring but what else can I do apart from that and some deft sealant on the base of the pan?
There is 20mm chipboard floor and 10mm floor tiling to work with.
Your suggestions are welcome,
TerryH.

 

[Last Plumber]

The subject line says it all!
The new close coupled pan/cistern I have to fit has its fixing holes directly over the main 22mm c/h pipes. I'd have to pack the cistern off by about 30 mm. to clear the pipes.
I'll fix with some short screws that don't penetrate the flooring but what else can I do apart from that and some deft sealant on the base of the pan?
There is 20mm chipboard floor and 10mm floor tiling to work with.
Your suggestions are welcome,
TerryH.

There's no point using screw that are too long anyway. Pick some that don't go all the way through.
Run a bead of silicon around the base of the pan after you've screwed it down.
Or, if you can be bothered with this extreme measure and you like things done in a belt and braces way.

Mark out and accurately cut a piece of 20 ply. The same shape as the inside of the pan base, glue that to the floor with that two part wood glue ( forgot name ) or screw it in places with no pipes. Then sit the pan over it and use screws that go through the ply/tile/and into the floor boards.
That way, when the house falls down in 100 years, your toilet will still be there

 

[Radioman]

There's no point using screw that are too long anyway. Pick some that don't go all the way through.
Run a bead of silicon around the base of the pan after you've screwed it down.
Or, if you can be bothered with this extreme measure and you like things done in a belt and braces way.

Mark out and accurately cut a piece of 20 ply. The same shape as the inside of the pan base, glue that to the floor with that two part wood glue ( forgot name ) or screw it in places with no pipes. Then sit the pan over it and use screws that go through the ply/tile/and into the floor boards.
That way, when the house falls down in 100 years, your toilet will still be there

That would work with side access holes but not with vertical fixings. I have moved pipes in the past.

 

[rpm]

That would work with side access holes but not with vertical fixings. I have moved pipes in the past.

All he is doing is increasing the amount of wood for the screws to bite into.

 

[Best]

Just use shorter screws to prevent going through the floor boards and a bead of clear silicone around the outer edge of pan. There is no way the pan (particularily large based pans) will move later if the floor tiles were clean. Silicone actually has an extremely strong grab on ceramics. Tbh, I have fitted pans with bluff screws, as often not required.
Mark below the pan that pipes are just below floor, to remind future workers