Understanding the layers of an underfloor heated floor

As the cosy warmth radiates up through your feet, it’s easy to take for granted the installation of underfloor heating.

Easily installed in many new and existing buildings, it provides consistent, efficient and controllable warmth whenever required.

However, what’s present beneath your feet can vary, depending on the system, property and installation.

So, as the UK’s most trusted name in underfloor heating, we thought we’d look beyond the benefits to explore the various layers which make up underfloor heating.

Layer 1 – The sub-floor

Broadly, underfloor heating sits below the top flooring surface – such as tiles, wood, laminate or lino – and above the solid sub-floor beneath.

In most properties – domestic or commercial – the sub-floor is typically either concrete (often with a level, screeded surface) or floor boards (sheets of chipboard in newer properties or traditional floor boards in older properties).

Whether you’ve opted for electric (dry) or wet (hydronic) underfloor heating may influence whether you can lay the heating system directly onto this surface – or require a further layer.

Layer 2 – Options

The second layer of flooring depends on the type of underfloor heating system chosen.

Electric Underfloor Heating

Electric (or dry) underfloor heating consists of electric heating elements within heating mats or cables which are installed beneath or within flooring. When the electricity is turned on, the heating elements warm up to heat the room.

There are three main types of electric underfloor heating – heating mats, foil heating mats and loose lay heating cables. Each is connected to the mains electricity supply and controlled via a thermostat.

Electric Underfloor Heating – Layer 2 – Insulation board

For solid floors, it is typically best to install a layer of insulation board before an electric underfloor heating system is laid.

Insulation board performs two purposes:

  1. It helps direct heat up through the floor (rather than down into the sub-floor)
  2. It provides a level surface onto which the heating system can be secured with adhesive or levelling compound

Our heating mats feature a mesh mat design which helps secure all elements prior to screeding.

Our loose lay heating cables can be stapled, tacked or glued into place, ready to be screeded.

Wet Underfloor Heating

Wet (or hydronic) underfloor heating uses a network of flexible pipes which are installed beneath the floor. Hot water is circulated through the pipework to warm the room from the floor upwards.

The pipes are connected to an existing boiler – or a renewable source, such as a heat pump – via a manifold which controls the temperature.

Wet Underfloor Heating – Layer 2 – Variations

When it comes to securing wet underfloor heating in place, there are a number of choices depending on the floor beneath:

  • Underfloor heating pipes can be laid directly into fresh screed.
    • If the screed is going to be thick (>2cm), a mesh sheet can be used to suspend the pipes closer to the surface to avoid too much downward heat transfer
    • If not, a castellated panel has a surface pattern similar to an egg box, into which the pipe can again be laid before screed is applied
  • On an existing screed sub-floor, underfloor heating pipes can be fitted into grooved underlay to hold them in place
  • Between wooden joisted floors (typically found upstairs in homes), aluminium plates can be placed between the joists to support the pipework below the height of the final floor
  • For situations where the final floor must not rise significantly, our LowPro+ is an overlay board which allows the pipe to lay securely in recessed grooves. It’s ideal for older buildings with wooden floors

Layer 3 – Underfloor heating system

The third layer in your heated floor is the underfloor heating system itself!

By this stage, you may have already weighed up the pros and cons and chosen either dry or wet.

Despite the different ways they work, there are a number of similar benefits to both systems.

Unlike a traditional radiator which warms the air closest to it, both wet and dry underfloor heating systems heat the whole of the floor. This produces a more evenly distributed and comfortable warmth.

Both use energy more efficiently than traditional radiators by running at a lower temperature. Without the need for bulky, metal radiators, they both allow for greater freedom of interior design.

Wet underfloor heating is typically favoured in larger buildings or homes which already have a traditional hot water based central heating system.

Electric underfloor heating is increasingly popular in smaller properties, renovations of existing properties and where solar panels provide the electricity used.

Layer 4 – Screed

The fourth layer is the screed, levelling compound or adhesive which covers the underfloor heating systems.

It can serve up to four key purposes:

  1. Secures the underfloor heating system in place
  2. Helps heat from the system dissipate evenly through the floor
  3. Provides a smooth and solid top surface for the final flooring
  4. Acts as an adhesive to secure the final flooring in place

Layer 5 – the visible flooring

The final layer is where you – or the purchasers or tenants of the property – get to install the functional and aesthetic flooring of your choice!

Underfloor heating is compatible with almost any available covering:

  • Solid or hardwood flooring or floor boards – durable, timeless and beautiful
  • Laminate or ‘engineered’ wood flooring – affordable, easy to install, hard wearing
  • Concrete flooring – functional, strong, can be polished or painted
  • Vinyl flooring or lino – water-resistant, easy to clean, available in various styles
  • Tiles – ceramic, porcelain, wide variety of designs
  • Low tog carpets – soft, warm and cosy under foot
  • And other surfaces including cork flooring, stone or composites

The choice of flooring will likely depend the room’s function, aesthetic preferences, budget and maintenance requirements.

The top layer choice is up to you!

How can Gaia help?

Here at Gaia, we have 35 years’ experience designing, supplying and installing both wet and electric underfloor heating systems in the UK and Ireland.

Whether it’s residential or commercial, we help our clients choose the best heating solution for their project.

Our expert team are always on hand to help homeowners, architects, contractors, M&E consultants, builders and developers with their underfloor heating needs.

Get in touch today to find out more.

Understanding the layers of an underfloor heated floor

Electric Underfloor Heating

We provide a range of electric (dry) underfloor heating systems, including self-adhesive mats, heating cables and decoupling membrane to warm any room.

Wet Underfloor Heating

We supply wet (hydronic) underfloor heating systems from top brands for a wide range of projects.

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