Is it necessary to add screed, MDF, and plywood before laying LFT for underfloor heating, or can the LFT be placed directly on top of the pipes?
Seeking help and advice, please!
Hey there, could an admin kindly approve this post? I’m trying to find a solution to a building works problem I’ve come across and I could really use some advice.
I’m a bit confused about the underfloor heating that’s currently being installed in my home. I’ve been told there should be screeding on top of or between the pipes. Do I also need to have MDF and then plywood before my LFT is laid? Apparently, there’s some kind of leveling compound that needs to be added to make sure the floor is all even.
I’ve read online that I can put screed to cover the pipes, let it dry, and then lay the LFT directly on top. Is that correct?
I’ve attached some photos to show the progress of the floor. In the second picture, there doesn’t seem to be any screeding between the pipes!
Any advice would be hugely appreciated. Thanks in advance.
We could use some additional photos
In order to get a proper answer, someone needs to have enough experience with this particular product to be considered an expert. It’s important to follow the manufacturer’s specifications to avoid any potential fire hazards.
Points out that it is a water-based system, not electric. Are you referring to specifications for pipes?
Discussing the heat system. Whether it’s electric or water-based, the goal is to generate heat. Failing to adhere to manufacturer specifications can lead to major issues down the road.
Is unsure why a water pipe would pose a fire hazard.
Makes a good point, everything has a specific temperature at which it can ignite. If heat is trapped and the surface reaches that temperature, it can potentially catch fire.
I heard the water temperature reaches about 120 degrees, I wonder what type of material can catch fire at that heat
In the U.S., permits would be needed for this type of project. If you are located there, inspections should be scheduled while the work is still in progress. It would be a good idea to consult with the officials responsible for approving the work.
Could you clarify which pipes you’re referring to? Are you talking about tubing?
Yep!
Some radiant heat systems utilize a unique underlayment or subfloor with channels cut into the sheets for snapping tubing at specific intervals. I believe poured cement systems came before the special subfloor systems. Getting additional advice and information would be beneficial.
Thank you! However, since the work has already started, I’m not sure if it would be feasible financially or logistically to tear things up and start over.
I wouldn’t recommend using MDF on a floor, electric infloor heating would have been more cost-effective and faster.
I once installed a radiant hydronic floor system. I laid down the piping, enclosed it with plywood as a standard practice, and then installed engineered flooring on top. The tops of the tubing were exposed, with the plywood securely holding them in place. My flooring was click-style bamboo hardwood on top of a thin foam underlayment. No leveling compound or cement was used, keeping it a standard radiant wood floor detail. (I also had radiant floors in concrete slabs, but those were on upper floors).
Effective r-value underneath is crucial. Otherwise, you’re heating up your crawlspace which should be sealed or you could be facing major issues in a couple of years.
The company carrying out the installation should have outstanding reviews and have been in business for at least 10 years. If not, pause the work and consult an HVAC specialist for a second opinion.
Mechanical contractors are the most reliable source of information on climate control.