Why is retro fitting UFH expensive + how much more?

[u587162]

Why is retro fitting under floor heating to an existing house more costly than for just a new extension with concrete floor?

How much more will it cost, percentage wise if the house does not have concrete floors but wooden joists?

 

[noseall]

Wet UFH or electric mat?

 

[Nozzle]

Is the floor of the old bit insulated? If not, that is where the cost is - cutting up an old floor laying the pipe and chucking in more screed

Nozzle

 

[ey143]

Wet UFH.

But I thought if you had old wooden floor boards/joists then they put the polystyrene type stuff between the joists (I could be wrong) and then the pipes rest on that?

How would you screed a 1st floor wooden floor anyway?

How much extra percentage wise would you say it costs?

 

[seasickstevie]

Just curious ... how come you show up under two different names?
(the other thread's like that as well)

 

[u587162]

Depends on if I'm using my husband's computer or mine (if my 2 year old allows me). Must be still logged in his profile as I click on my email notification.

 

[mointainwalker]

[/quote]But I thought if you had old wooden floor boards/joists then they put the polystyrene type stuff between the joists (I could be wrong) and then the pipes rest on that? [/quote]

And what would hold up the polystyrene when the 130 kg/m2 screed mix was poured on ?

[/quote]How would you screed a 1st floor wooden floor anyway? [/quote]

Polystyrene or foam 120 mm high, min 7 mm thick, around all sides allowing for expansion, plastic-sheet over floor to prevent screed running through cracks. Obviously assuming joists strong enough.

[/quote]How much extra percentage wise would you say it costs?[/quote]

Too vague, be more specific as to what it is being compared with.

P.S. My comments above given from point-of-view using an anhydride
liquid screed but biscuit screed not really any different.

PPS Is it just me or are other posters also finding that the quote function no longer works correctly (see above )

 

[noseall]

PPS Is it just me or are other posters also finding that the quote function no longer works correctly (see above )

Mines ok.

 

[SimonH2]

But I thought if you had old wooden floor boards/joists then they put the polystyrene type stuff between the joists (I could be wrong) and then the pipes rest on that?

Or, you pull up the boards, put the UFH pipes in with aluminium heat spreader plates, then re-board. That's how my brother's upstairs was done, apart from being a near total internal rebuild so no "lifting the old boards" first.

PPS Is it just me or are other posters also finding that the quote function no longer works correctly (see above )

It's the way you do it.
Each quote needs to start with a "quote" tag and end with a "/quote" tag. You've opened with a "/quote" tags so all you have is a load of unmatched closing tags. The way I do it is to copy the "/quote" tag from the end (including the square braces) and paste in where I want quoted bits to start/end. The important bit is deleting the "/" at the start of a quoted section.