Underfloor heating (UFH), the best option for garage conversion? If you’re researching heating solutions for your garage, check out our main guide on heating a garage conversion to see what we recommend.

Underfloor heating doesn’t feature in the main guide as we consider it of limited application for most garage conversions. In this article we discuss why and delve into the scenarios where it does make sense to at least get a quote on underfloor heating.

Garage conversions are on the upward trend with main drivers being home offices, home gyms and multigenerational living. A huge part of making the space comfortable for use as a room is the heating and insulation details. We would advise you pay particular attention to the latter and aim to reduce the energy demand of the new space to reduce the ongoing costs of heating your garage conversion.

Water based systems

This article discusses underfloor heating from a water fed also known as a Hydronic system perspective. Electric underfloor heating will be covered in another article. Electric underfloor heating has higher running costs than water-based systems and the other solutions covered in our main heating guide.

UFH The obvious choice for garages?

Most garage spaces will be lower than the main house, typically by about 150mm which provides the perfect opportunity for the multiple layers of insulation, pipework and screed required in an UHF system. Furthermore, gas boilers are commonly installed in the garage space which allows convenient access to install the UFH manifold. UFH also has a great reputation as an energy efficient way of heating your home so its easy to see why it may appear the obvious choice in situations when your home offers a straightforward install.

Cheapest garage underfloor heating kit

We found this kit online at a surprisingly affordable price point, although it did state last few. While we have not fitted the kits ourselves I did research the kit and found it comes with everything you need to provide underfloor heating to a garage. See our pricing table below for further details and options for double and triple garages.


Should you do it and is it better than the other options?

In terms of ongoing cost its hard to argue against the benefits of underfloor heating. Currently gas prices are far lower per kWh than electricity. And when you use that gas to heat a large body of water to a low temperature it’s an extremely efficient way of heating a space.

why is underfloor heating so efficient?

This boils down (no pun intended) to the lower input temperature required by a UFH system. A gas boiler will heat water in a conventional radiator-based system to between 60-80 degrees depending on the size of your radiators and your comfort level. Whereas a boiler feeding an UFH system will heat water to a far lower temperature of 40-55 degrees which is of course cheaper as it requires less energy/gas to be used. The lower temperature can achieve the same room temperature and comfort level because the volume of water is greater and more evenly distributed.


Drawback of underfloor heating systems for garage conversions

Simply put its more expensive to buy and more difficult to install than most other solutions.  Additionally, experienced UFH engineers can be hard to find or have long lead times. Of course, the extra upfront cost will be balanced out over time if the room you intend to heat is in frequent use.

UFH Finished Flooring Options

Finish flooring options can compromise the performance of the system and your preferred flooring surface could even be incompatible. This table summarises what you need to consider and clarify at the outset.

Finished Floor Surface

Consideration

Carpet

The tog rating which could restrict heat being dissipated to the room. Aim for a combined rating under 2.5

Wood Flooring

The moisture content which should be under 8% (Solid Wood Flooring Company, 2010)

LVT and Laminate

Maximum surface temperature advised by manufacturer vs the designed system temperature. (Typically 27 Degrees)

Tile

Generally compatible, decoupling layer should be included.

Deciding between Underfloor Heating vs Aircon and other alternatives

As we have already discussed the existing construction of your home may increase the feasibility of installing UFH as the system of choice. However, the ultimate decision should include a range of other factors and your own personal preference. As a man that suffers from cold feet and works 3-4 days a week from a home office I would appreciate the luxury of underfloor heating. That being said I would still opt for air conditioning as concluded in the main heating guide as I feel it offers the best balance of upfront costs, ongoing cost and features. On the other hand, if I were planning a yoga studio conversion where lots of time would be spent lying on and in contact with the floor then UFH would be my system of choice.

The lists below will help you to make the decision or at least guide how much further thought you should put into researching UFH as a solution. They are based somewhat on my own opinion as a surveyor and influenced by my goal of balancing value for money for both upfront and ongoing costs.

When to favour UFH

  • Your existing garage floor is at least 100mm beneath the desired finished floor level.
  • Your room will be used extensively and require heating to be comfortable, for example a home office used five days per week.
  • A double or triple garage conversion or granny flat conversions
  • Your existing system is fed by a heat pump

When to forget UFH

  • Small single conversions that will be used infrequently, for example guest bedrooms and utility rooms.
  • When the garage floor slab is level with existing house, and you are knocking through to connect the to the new space. UFH requires a floor build up of around 100mm which would cause a step into your new room.
  • You have limited budget for upfront costs.

Underfloor Heating Kits and installation costs

Trade suppliers seem to recognise the demand for small retrofit UFH systems and have produced packages developed with such projects in mind. They offer a one zone garage underfloor heating kit with everything you need including manifolds, pump, blending valve, actuator, pipework, track and even the room thermostat for a fixed price. The table below shows the costs for standard garage sizes.

Garage Size

Square Meters

Kit Cost - Click Image

Single

Up to 15 sqm

Double

25-35 sqm

Triple

35-60 sqm

Final Thoughts

Additional costs for labour and screed materials will vary depending on the part of the country due to local labour prices. Use this free quote service to get an install price for the kits from a local UFH engineer.  

I would be interested to hear from any readers who install these kits and don’t mind sharing the install costs for their part of the country. This data would improve the article and help future readers.

Frequently Asked Questions

Q. Can I use UFH to heat my garage conversion and remaining garage space.

Yes you can use a single zone kit to provide heating across the entire floor area. Although this is difficult/costly as a retrofit project due to the floor build up required. It is of course still possible but may require a complete new floor slab. If you only want background heat to the garage side to keep your workshop and car at a controlled temperature, then I advise you to increase the spacing between loops to 300mm.  

Resources and Further Reading

The Solid Wood Company (2010) WOODEN FLOORS AND UNDERFLOOR HEATING [online] Available at: https://buildingcentre.co.uk/media/_file/pdf/22183_pdf9.pdf

Nu Heat (No Date) 5 Must ask questions when considering UFH in your home

Beama (2020) Beama underfloor heating control guide for domestic properties [online] available at: https://www.beama.org.uk/static/49eb801f-0bfd-4499-a4fe7a32c3fa6b11/228b4d50-f795-4817-ac957ba0d1c66f64/BEAMA-UNDERFLOOR-HEATING-CONTROLS-GUIDE-FOR-DOMESTIC-PROPERTIES.pdf

About the Author Michael NEGC


Michael is the Architectural Designer and Surveyor at North East Garage Conversions.
Michael has a HNC in Civil Engineering and a HND in Construction Management. Previous experience includes multiple renovations, a self build plus working as an Architectural Technician, Designer and Project Manager.

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