We had Karndean (Van Gogh) fitted over electric underfloor heating about 18 months ago. In the last 6 months or so, we have noticed lines running across the floor boards which didn't used to be there. These must be related to the underfloor heating as they're only in 3 out of the 5 rooms fitted with Karndean which have underfloor heating, the 2 rooms without underfloor heating are fine. Note the thermostat is set to floor temperature and has never been set above 24 / 25 degrees (maximum temperature recommended by Karndean is 27 degrees). The lines are generally fairly straight and run across several floor boards, and are also often (although not always) a uniform distance apart. They run at 90 degrees to the direction of the underfloor heating wires i.e. do not follow the direction the wires run. We're of mixed opinion regarding whether the lines are indented, raised or discoloured (sorry not very helpful!) - although as you can't see them if you stand right on top of them and look down I suspect it's not discolouration but a different level. The original floor was tiled. Insulation boards were put down followed by the electric heating wires and then covered in 2 levels of latex. The electrician who fitted the underfloor heating instructed the floor fitter how much latex to put down (8mm I think), so to the best of my knowledge sufficient latex was put down although I can't be certain as this hasn't been checked. The underfloor heating (installed by a qualified electrician) is on 2 different systems and thermostats, making it less likely (but still possible) that there's a fault with the underfloor heating system which is allowing the floor to get above the 27 degree limit. Would appreciate any advice regarding how to take things forward. In particular: - Has anyone else experienced this issue with Karndean (see photos - the lines run from left to right of the pictures in the opposite direction to the way the floorboards are laid) - Do the lines look / sound typical of what might happen if the Karndean floor gets too hot (whether due to insufficient latex or the underfloor heating getting too hot?) - How do we best check whether the required amount of latex was put down? - Is there a specific type of latex which should have been used over the underfloor heating? - Could the lines be cause by cracks in the latex? Anything else you can think of too would be most appreciated. Thank you!
Looks like the latex may have cracked. Maybe uplift a section and check the subfloor? Sent from my iPhone using Tapatalk
Thank you. What are possible reasons for the screed cracking over the underfloor heating? I'm guessing either the screed isn't thick enough, the wrong type of latex was used (is there a right and wrong type?) or the underfloor heating is getting too hot? How easy is it to lift a bit of floor to find out? When I suggested this to the floor fitter he said that it might pull up the latex and damage the underfloor heating. Also that it will be difficult to get the screed level again to refix it. Not sure if he was trying to deter us from going down that route though!
Heat gun and warm the plank up and peel back slowly, too quick then it can rip up chunks of screed especially if its already cracked then its likely to come away anyway. Its got to be investigated either way do your fitter just needs to do what is required......and thats to have a look under the planking.
Could be lots of reasons. Wrong screed, unstable subfloor, lvt fitted before screeds dried. Shouldn't be hard to lift....unless the subfloors really bad! Sent from my iPhone using Tapatalk
Thanks - if the Karndean was fitted before the screed was dry, or the ufh was turned up too quickly following installation (can't remember exactly what we did but would have followed the instructions we were given), would the cracks have occured sooner? I'm guessing I first spotted the lines on the Karndean after about 12 - 15 months. Now they're multiplying and the floor is starting to resemble spaghetti junction.......
Cut a plank into strips about an inch wide and use some heat while you pull them up. Also I would have recommended a fibre based smoothing compound, and that the underfloor heating was turned on gradually until at normal operating temperatures, as smoothing compounds take several weeks to reach full strength. Sent from my SM-G930F using Tapatalk
