When it comes to underfloor heating, ensuring a flawless installation is crucial. While the idea of warmth radiating evenly from the ground up is appealing, errors during project planning and installation can lead to inefficiency, discomfort, and costly repairs.
Mike Beck, Managing Director at Trade Underfloor, shares the nine most common mistakes and how to avoid them, so you can meet – and exceed – your customers’ expectations.
Proper insulation is vital in any UFH installation. Without it, heat can escape into the subfloor instead of rising into the room, causing inefficient heating and increasing your customer’s energy bills.
Sometimes, when there are limitations on floor height build-up, it can tempting to reduce insulation or even leave it out altogether. If your project subfloor doesn’t have insulation (common in older houses), it doesn’t always mean a costly dig out and re-screed.
Our insulated panel systems – RetroTherm® Lite and RetroTherm® Backer Board – are designed for retrofits, combining insulation and heating in one low profile system. Using premium high-density XPS polystyrene, with heat conducting materials on the top face of the board, also enhances performance.
When floor height is an issue and even a low profile system is a squeeze, there are work arounds for certain issues. For example, low thresholds at external doorways can be overcome with a mat well. It’s best to discuss these possibilities with the homeowner in advance, before they come to light during install.
How to avoid it:
Know your project build up heights and always include insulation or an insulated retrofit panel system in your install plan, if the floor is not already insulated.
Customers are often undecided on their floor coverings at UFH quoting stage, but it’s still a good time to provide some pointers and prevent problems later in the process.
Not all floor types work well with UFH – incompatible coverings can restrict heat flow, increase bills, or even be subject to costly damage.
Tiles and stone are excellent conductors, while certain natural woods and thick carpets can restrict heat flow and reduce UFH performance. Engineered wood is generally more stable than solid wood, and carpets should have low tog ratings with UFH-compatible underlays that allow more heat to permeate through. Where a customer has specific floor coverings in mind that are heat-sensitive, advise them on installing floor sensors to protect the floor.
How to avoid it:
Discuss floor finishes with the homeowner early, recommend UFH-friendly options and install floor sensors to prevent overheating where necessary.
Even a simple single-zone extension benefits from a CAD design. Professional underfloor heating designs tick many boxes when ensuring the system can deliver adequate and consistent heat outputs, and saving valuable time on site:
Benefits of a CAD design:
✓ Optimum manifold location
✓ Efficient pipe spacings and layout
✓ Maximum loop lengths
✓ Accurate kit quantities
✓ Water temperature and flow rate settings
✓ A record for future reference
Working with a professional design and supply business such as Trade Underfloor guarantees compliance with BS EN 1264 and gives homeowners reassurance that their system has been designed and installed to the highest standard.
How to avoid it:
Invest in a CAD design for every project, regardless of size or complexity.
Wiring mistakes are a common cause of UFH faults and poor system performance — from swapped live/neutral connections to thermostats wired to the wrong actuator.
Poorly positioned floor sensors are equally responsible for problems down the line. Floor sensors are not always necessary, but in some scenarios, such as heat-sensitive floor coverings, they are crucial. Place them too far from pipes and they’ll under-read; too close and they’ll over-read, leading to inefficient control.
These errors lead to nuisance call-backs, wasted time, and strained customer relationships.
How to avoid it:
Use a qualified electrician, refer to wiring centre instructions, maintain good cable management, place floor sensors according to manufacturer guidance, and double-check connections before commissioning.
Paying attention to manufacturer advice is particularly important when it comes to product compatibility. Products specified within an underfloor heating system are rigorously tested to ensure they perform when used in conjunction with one another. Switching primers, adhesives, boards and screeds for alternatives can cause unintended costly consequences.
If products are not installed as per manufacturer instructions, warranties and insurances will often be affected as well.
How to avoid it:
Seek advice on compatibility when using products for the first time.
There are many screeds on the market and the right screed for your project depends on the system you’re installing, as well as other factors such as build schedule.
Typical pitfalls include opting for an anhydrite flow screed when floor coverings need to be installed quickly – leaving moisture in your subfloor. Going for the wrong self-levelling compound over a panel system can pull the boards off the floor. And remember that low-profile systems require different screed properties than more traditional pipe in screed floors.
How to avoid it:
Get advice from your UFH or screed supplier when installing a new type of system for the first time.
Rushing installations often leads to mistakes. Each floor system has its own requirements — from priming substrates to panel cutting — which take time. Skipping steps can compromise system integrity, durability and performance.
Investing in the right time-saving tools (such as clip guns and pipe decoilers) is the best way to speed up installs.
How to avoid it:
Allow realistic time for each stage and equip yourself with the right tools.
The importance of a thorough pressure test before leaving site or pouring screed can’t be underestimated. We recommend pressure testing with water, unless site conditions dictate that an air pressure test is the only viable option. This is because whilst air can be compressed, water can’t, so an air test doesn’t accurately simulate a water test.
Fill and vent the system, ensuring no air is trapped, and pressure test at 6 bar for at least one hour. Once tested, the system pressure can be dropped to 1-2 bar, or released entirely.
In hot summer conditions, pressure can rise due to thermal expansion — so be prepared to release excess pressure if required.
A second round of testing should be completed at commissioning, including checks on thermostat communication, actuator response, water temperature, and flow rates against the CAD design.
How to avoid it:
Test every system thoroughly with water, and before screeding. Account for seasonal temperature changes.
No matter how professional the install, the final impression matters. Leaving without a proper handover can undermine trust in your hard work and create frustration at a later date.
Providing project documentation — CAD design, commissioning sheet, and control manuals — wraps the job up professionally and leaves a lasting positive impression.
How to avoid it:
Always leave clear documentation and walk the homeowner through their new system.
In the world of modern construction, trade professionals know that heating systems are a critical component in both new builds
As part of our extended range we now stock the Gerpex Multilayer and Press Fittings Range The pipe system has
