When installing underfloor heating (UFH) systems under a screed floor it is essential you give due consideration to your choice of screed.
There are different types of UFH systems, and different types of screed. Getting the combination right will ensure the floor remains in good condition, and the efficiency of the UFH system is optimised, to save money in the long term.
Types of underfloor heating systems
There are two main types of underfloor heating systems; wet and dry.
Dry underfloor heating systems consist of cables and matting, and are operated by electricity. Wet underfloor heating systems are connected to a heat source such as a boiler or renewable air source heat pump which supplies heated water to the UFH system’s pipework.
Wet underfloor heating systems are cheaper to run but more expensive to install than electric systems.
Arguably, a wet underfloor heating system works most efficiently, and therefore cost-effectively, under a screed floor. Screed underfloor heating systems are ideal for new builds and extensions and for covering large spaces. Because electric underfloor heating systems are more expensive to run, they are more suited to smaller spaces.
Types of screed for UFH systems
Types of screed for UFH systems are:
- Dry, traditional sand and cement screed
- Liquid screed made from anhydrite materials or cement
Traditional screeds are installed by labourers who manually mix, transport, lay and finish the screed. Lasers and spirit levels are used to ensure the screed is perfectly flat.
Liquid screed is pumped directly to where it is needed. It self-levels, which drastically reduces the labour hours on the project, and self-compacts which means the screed naturally envelopes the pipework without causing voids from which heat could escape.
What to consider when choosing screed for wet underfloor heating systems
Thermal conductivity
The thermal conductivity of a screed floor will have a direct impact on the efficiency of the UFH system. Cementitious liquid screed from our sister company, Clockwork Screed, delivers exceptional thermal conductivity which improves the performance and responsiveness of the UFH system.
Drying time
Traditional screeds can take around 21 days to cure, whereas cementitious liquid screeds can withstand light foot traffic within 24 to 48 hours of being laid.
Strength and durability
Liquid screed is exceptionally strong, to the extent that it can be laid as thinly as 25mm, and it has shrinkage rates of under 0.05% which reduces the potential for cracking.
Compatibility with underfloor heating systems
While most screeds are compatible with both wet and dry UFH systems, anhydrite screeds need to be sealed before the final floor finish is applied. Liquid screeds perform exceptionally well in moisture-sensitive areas, needing to only achieve moisture levels of 2.5%CM, whereas anhydrite screeds need to achieve lower moisture levels at around 0.5%CM.
Guidelines for UFH screeding
Depth: For liquid screeds, a minimum depth of about 20mm above the pipes is required, so 35-50mm in total including the pipework.
Steady pouring: Starting at the furthest point away from the door, allow the screed to flow naturally when pumped, guiding it to ensure an even distribution.
Force-Drying: Before switching on the UFH system, the screed must be fully cured to avoid cracking. Only then should you gradually increase the temperature.
Clockwork Underfloor Heating and Clockwork Screed
Clockwork Underfloor Heating works in collaboration with its sister company, Clockwork Screed to provide a one-stop-shop service for UFH installation with a screed floor.
Get in touch to discuss your underfloor heating project.
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.
