Tilling on a floor with Karndean already on floor & underfloor heating

[raylincs]

Hi Everyone
Looking for some advise.
I have just been to look at a job that has, Karndean flooring on a concrete floor substrate, and has electric underfloor heating.
1. Would you take up the Karndean floor (in V good nick)
2. If not taking up the Karndean, what adhesive would you use?

Many thanks
Raylincs

 

[cam_low]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Karndean up, remove as much glue as physically possible, prime with SBR, self level, or not, then tile.

 

[raylincs]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Karndean up, remove as much glue as physically possible, prime with SBR, self level, or not, then tile.

Hi Cam_low
Thanks for replying, the area is 40sqm and the Karndean has been put down with special adhesive for underfloor heating. I was wondering if i could rough-up the surface of the Karndean, then prime with SBR and tile with flexible adhesive.
Thx

 

[Rookery]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

I've tiled straight onto Karndean with 600 x 600 porcelain using BAL tile and stone PTB. As long as the Karndean really is well fixed, give it a good clean, rinse, dry and tile away.

 

[nybor62]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

take up karndean imo, what tiles are u fixing

 

[ythan]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

are you sure it's electric underfloor heating within the concrete floor substrate? sounds unusual but maybe there's insulation under the concrete to prevent large heat loss.

if it is electric then maybe a few problems:

- the electric matt/cable will have been laid in a relatively thin screed on top of the concrete slab- removal of the karndean may result in damage to screed and the electric matt/cable. the karndean can be pretty difficult to remove.

- is it possible the karndean will overheat when covered by tiling - probably not.

don't think there's any problem with tile tiles sticking to the karndean - to be safe use Bal single part Fastflex, which is lower cost and much easier to use than the 2 part fastflex.

suggest you could do a trial fixing of say a square meter of tiling to check for any problems - it is a large floor area.

 

[peteablard]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Take it up, why risk it? If a jobs worth doing.........

 

[raylincs]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Thanks to everyone who has replied. Just to clarify I have found out; the electric underfloor heating is a thick cable laid into a weak sharp-sand and cement substrate (insulation under this) with a thin self-levelling compound on top. The Karndean has been put on with Karndean's own underfloor heating adhesive.
The area to tile is 40sqm with Porcelain 390 x 590 x 10mm tiles.
It sounds as though the replies are split between taking the Karndean up and leaving it down.......
I appreciate the replies

 

[ythan]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Risk = (probability of something happening) times (the consequence of it happening).


Why it worrh taking a risk? - to win benefit for the risk taker.



Solution:
Share understanding of the risk with the customer, get the job, and share the benefit with the customer.

How much would it cost to take all the Karndean up, level etc? And what's the risk of damage to the electric underfloor heating?

I'd go with tiling over the karndean with Bal single part fastflex.

Talk to your customer.

 

[Ajax123]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Thanks to everyone who has replied. Just to clarify I have found out; the electric underfloor heating is a thick cable laid into a weak sharp-sand and cement substrate (insulation under this) with a thin self-levelling compound on top. The Karndean has been put on with Karndean's own underfloor heating adhesive.
The area to tile is 40sqm with Porcelain 390 x 590 x 10mm tiles.
It sounds as though the replies are split between taking the Karndean up and leaving it down.......
I appreciate the replies

That has failure written all over it.

Also the adhesive will have a temperature condition on it. From memory i thinkthe karndean adhesive is such It should not exceed 35degrees c (or might be a lower spec a 29degree adhesive). This is important because as you are tiling you will significantly increase the temperature at the gue line as your tile will move the temperature thresholds within the floor strata upwards. This could easily increase the temperature at the karndean glue line above its safe threshold causing it to soften and delaminate.

i am firmly with the "take the karndean up and remove as much glue as possible then self level and tile" crowd

 

[ythan]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Ajax - are you also going to take up the ''weak'' screed and the electric underfloor heating?

who is going to pay for all this???

 

[raylincs]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Hi everyone again thanks for taking the time to answer my post.
The underfloor heating never goes above 25c so that shouldn't impact the glue line (glue is Karndean's own for underfloor heating, so I will check their temperature threshold), also the tiles should disperse any temperature build up, I would have thought.
The customer of course is hoping for the Karndean to be taken up, and all the problems and costs this would entail.
I take pride in my work and rely on repeat business, so in a fix about this job.
Thx

 

[peteablard]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Hi everyone again thanks for taking the time to answer my post.
The underfloor heating never goes above 25c so that shouldn't impact the glue line (glue is Karndean's own for underfloor heating, so I will check their temperature threshold), also the tiles should disperse any temperature build up, I would have thought.
The customer of course is hoping for the Karndean to be taken up, and all the problems and costs this would entail.
I take pride in my work and rely on repeat business, so in a fix about this job.
Thx

If the customer wants it taken up then why are you asking about leaving it down?

 

[raylincs]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

Sorry missed the word Not, out..
The customer of course is hoping for the Karndean NOT to be taken up, and all the problems and costs this would entail

 

[ythan]

Re: Tilling on a floor with Karndean already on floor & underfloor hea

if cost to the customer is no problem, then it's all down your own professional responsibility.

and if your customer is pleased & can put your way other customers, that also do not consider cost, then you've have even more professional responsibility and plenty of work.

beware damaging the electric underfloor heating.....

talk to your customer and get him/her to agree to what you recommend doing.