Wet underfloor heating system screed enhances a UFH system’s performance.
What are wet underfloor heating systems?
Wet underfloor heating systems consist of a network of pipes laid onto a subfloor in a uniform layout. A traditional boiler or water source heat pump circulates warm water through the pipes to provide evenly distributed heat throughout a room.
A wet underfloor heating system operates at temperatures far lower than radiators, so they are ideal for large spaces. They are also cheaper to run than dry (electric) underfloor heating systems.
Screed underfloor heating
Screed underfloor heating is the installation of an underfloor heating system under a screed floor. The UFH system can be either dry (electric) or wet, which consists of pipework heated from a boiler or renewable heat source.
The cementitious liquid screed we supply is strong and durable with exceptional thermal conductivity. It is also self-levelling, and self-compacts so the liquid naturally covers all the pipework to prevent gaps from developing which would allow heat to escape down into the subfloor. All of these benefits optimise the performance of the UFH system, making liquid screed the ideal choice for underfloor heating systems.
Screed depth and underfloor heating
So, back to our original question. How thick should screed be over underfloor heating pipes?
For wet underfloor heating systems, the required depth is between 40mm and 75mm, depending on the type of screed used. This includes the diameter of the pipes. For all screed types, around 20 to 30mm of the screed needs to be above the pipes.
On dry underfloor heating systems, significantly less screed is required. The minimum depth is 10mm above the cables, although an additional 5 to 10mm improves the heat distribution and reduces the risk of damage during installation.
Wet underfloor heating screed
So what is wet underfloor heating screed?
Wet underfloor heating screed is a thin layer of concrete or mortar that is poured over an underfloor heating system to create a smooth floor, ready for a final floor finish such as vinyl, wood or tiles.
What does screed do in a UFH system?
It is widely believed that screed optimises the output of heat from a UFH system, allowing the floor to heat evenly with excellent response times.
The screed encases and protects the pipework, and acts as a thermal mass that absorbs the heat from the UFH system and then releases it gradually to all areas of the room.
Types of screed used over UFH
The two main types of screed used over UFH are traditional sand and cement screed, and liquid screed.
Traditional sand and cement screed takes longer to install than liquid screed and is prone to air pockets when it is not adequately compacted. These air pockets allow heat to escape which impacts the efficiency of the underfloor heating system.
Liquid screed, as supplied by Clockwork Underfloor Heating through our sister company Clockwork Screed, is now preferred by a large majority of screed installers because of its speedy installation and superior thermal conductivity. Once pumped, its liquid form allows the screed to self-level to produce an even floor. It then self-compacts around the pipework to avoid the formation of air pockets.
How to apply screed over wet underfloor heating
To apply screed over a wet underfloor heating system:
- Prepare the subfloor – check it is clean, dry and structurally sound
- Lay insulation
- Install and fix the underfloor heating pipework
- Decide on the depth of screed
- Pump the screed and leave it to self-level for around 48 hours
- Allow the screed to dry naturally for around 7 days, after which heat can be gradually introduced from the system starting at around 20-25°C, and increasing by a few degrees each day
- Lay the final floor finish.
This is a short summary of the process for applying screed over a wet UFH system. We’d strongly advise appointing a professional underfloor heating installer such as Clockwork UFH to complete the project to the required standards.
Recommended screed depth over underfloor heating pipes
Due to its impressive strength, liquid screed can be laid very thinly which enhances the distribution of heat and saves on material costs.
While a traditional sand and cement screed depth over underfloor heating pipes is typically between 65 and 75mm including the depth of the pipes, liquid screed can be laid anywhere between 45 and 65mm. For a level finish, the screed depth should be measured from the highest spot of the subfloor.
Your local screed underfloor heating system installer
Clockwork Underfloor Heating is your local screed underfloor heating system installer, offering decades of experience. Get in touch for help with your wet underfloor heating system screed installation.
Plan, Insulate, Heat and Screed
Our 4 Step Process
1
Planning & design
2
Lay insulation
3
Install underfloor heating
4
Pour liquid floor screed
PROJECT FOCUS
High end Residential, Manchester
We planned and installed an underfloor heating system into a contemporary home in Manchester. Not only that, we finished the installation with a smooth, even and high quality liquid floor screed.
Our team worked with the end user’s architect, ensuring the home benefitted with a visually striking but also inherently comfortable and environmentally conscious heating solution.
The client now enjoys an enhanced living experience, reduced energy bills, and an aesthetically uncompromised living space that flows through the whole house.
See What Our
Customers Say
“From our initial consultations to the flawless installation, Clockwork’s team demonstrated not just technical prowess, but a nuanced understanding of architectural essentials.
Their underfloor heating system effortlessly merged into our designs, preserving every ounce of spatial aesthetics while embedding an unperceivable, yet palpably comforting warmth throughout the residence.
In Clockwork, I found more than a solution provider; I discovered collaborators who understand, respect, and enhance the architectural journey. Their integrative approach, precision, and unyielding commitment to quality have made them my go-to partners for all underfloor heating needs.”
D. Smith
Architect, Cheshire
Why work with us
For your Underfloor Heating Project?
Expertise in underfloor heating: Specialists in underfloor heating installation for residential and commercial needs.
Unique advantages: Providing distinct benefits over traditional heating methods to both homeowners and businesses.
One-stop solution: Offering a comprehensive four-step process (Plan, Insulate, Heat, & Screed) for a streamlined underfloor heating solution.
Collaborative approach: In partnership with our sister company, Clockwork Screed, ensuring a unified solution for insulation, underfloor heating, and screeding.
Simplified project management: Eliminating the complexity of dealing with multiple suppliers, facilitating a smoother and hassle-free project execution for architects, contractors, and homeowners.
