Question on UFH

[John Benton]

Has anybody installed porcelain over the JG Underfit system?

This has already been fitted between joists and then 18mm chipboard glued and screwed to joists. Plumber says to put insulation boards over top and tile and my supplier is saying Hardi and then tile.

Whats the best route, first time I have come across this system?

Cheers

John

 

[cam_low]

I think I remember reading about this system somewhere previously and the outcome was to hardie over the top That is a guess from memory so best to wait on others reply John.

 

[Ian]

Insulation boards wouldn't be very good for heat transfer, hardies is the logical answer IMO.

 

[John Benton]

Thats what I thought guys, the insulation board would hold the heat rather than let it pass through to the tile. Couldn't see anything on the Speedifit website to indicate what board should be going down other than saying you can use any of the following floor coverings.

 

[John Benton]

Anymore answers?

 

[Sean Page]

I've only come across this type of heating upstairs once. I recommended hardie boards or at least plywood and insulation boards screwed every 150mm.

The customer had other ideas as they had been told the heat would only permeate upto 25mm. The pipework was stapled direct to the underside of the chipboard flooring (22mm) and allowing for the tiles and adhesive would already take the total depth to over the 25mm. I tried to convince the customer of the impending problems but they were very adamant, the people at the Ideal Homes expo had said etc etc etc.

In the end I was told to tile as per their instructions and ignoring my advice and experience they would take full responsibility.

Within six weeks all three bathroom floors had cracked exactly where I said they would. My name was mud with the customer as "I hadn't fully explained" luckily the main contractor had been present throughout our discussions and could back me up totally.

The customer learned an expensive lesson, but the moral is to make the proper preparations.

I personally would go hardie boards

 

[John Benton]

Cheers Sean just backed up the other guys and my thoughts, have quoted and got the job now so Hardie it is

 

[AliGage]

The idea of outting an "insulation" board over the top of UFH is nuts, no?