sub floor types for installing underfloor heating

Choosing the Best Underfloor Heating System For Your Project

It is important to select the right underfloor heating system that aligns with your building structure. In this guide, we look at various subfloor types and the best wet underfloor heating system to install. This guide will explain the most appropriate systems and which products you require to install an underfloor heating wet system.

Types of floor construction

Each floor construction has a different method of installing an underfloor heating system. Understanding these variations is key when choosing the best underfloor heating system for your project

underfloor heating pipes for wet underfloor heating system

New Flooring (Screed)

Installing a new floor is most common in new builds or extension projects. This provides the opportunity to embed the wet underfloor heating system in the screed. This creates a solid surface and is the most efficient method of installation in terms of conductivity.

solid concrete subfloor

Existing Solid Flooring

Solid flooring refers to surfaces like concrete or similar sturdy materials. This applies to wooden floorboards if you prefer not to lift or replace them. Installing underfloor heating on solid flooring requires an overlay system. You secure boards onto the existing floor.

joisted flooring with no floor boards

Suspended Flooring

Joisted flooring comprises a framework supporting the floor surface. The best underfloor heating systems for this type are fitted between the joists. There are various ways of achieving this method without affecting the structure of the floor.

Underfloor heating systems
New Flooring


In new construction, screed systems involve embedding UFH pipes within a structural concrete floor. As well as being a structural element, the screed is an excellent conduit which facilitates even heat distribution. Pipes are secured to insulation using varying methods:

Staples: Pushed into insulation by hand, mallet or staple gun. Staples have a hooked design to hold pipes securely in place.

Self-adhesive rail: used alongside clips to allow easier & more secure pipe placement. Reducing installation time and costs for underfloor heating systems.

Screed Panels: Used instead of rails & staples. Perfect for ensuring accurate pipe spacing and even heat distribution. Made from 100% recycled high-impact plastic. Spaced in 50 mm increments.

Key Features

  • Excellent heat conductivity
  • Ideal for consistent and efficient heating in newly built properties
  • Longer installation time
  • Less feasible to retrofit existing structures

Ideal Applications: A screed system is best suited for new constructions where it can be integrated during the building phase. Either a newly built property or an extension.

screed covering pipes of a wet underfloor heating system

Underfloor heating systems
Existing solid floor


Screed is also applicable to solid floors (excluding timber or joisted structures). The subfloor is solid, a screed applied on top doesn’t need to serve a structural purpose. A thinner layer of screed can cover the underfloor heating pipes. This becomes an excellent choice when using wet screed panels. The reduced thickness compared to standard screed.

Ideal Applications: Solid concrete floors. Where a floor build-up of around 20 mm-30 mm is acceptable. Longer installation time is acceptable due to curing time.

Overlay Panel System

EPS moulded panels enable quick and simple installation of underfloor heating onto both suspended and concrete floors. EPS panels are made from lightweight expanded polystyrene with pre-formed grooves in which the heating pipe is inserted. The panels are installed directly on top of both solid and timber floors. The panels are foil-coated and have a low thermal mass, which is conducive to swift responses to changes in temperature. With a minimal height increase of just 20mm and a high compressive strength of 400 kPa, they are very lightweight meaning they are simple to fit and unobtrusive. The panels are made to house 16mm pipework, spaced at 150mm. The panels should be secured with adhesive and can be laid onto any existing, level flooring.

Key Features

  • Low Profile only 20mm
  • installed on existing flooring, minimal preparation
  • Easy installation
  • High compressive strength

Ideal Applications: Perfect for retrofitting projects where floor height constraints exist and minimal disruption is desired.

eps overlay panels placed in a room for underfloor heating system

Underfloor heating systems
Suspended timber flooring

Dry Screed

Underfloor heating can be installed on a suspended floor using a dry screed mix. The underfloor heating wet system is installed onto a layer of rigid insulation between the joists. A dry screed is laid, neatly containing all of the pipework and bringing the level to the top of the joists. As screed is an effective heat conduit, it is the ideal material to fill the void between the insulation and the floorboards.

Care should be taken to ensure the joists can support the weight of the dry mix. The dry mix is not intended to be structural – it merely acts as a conduit for heat transfer.

Key Features

  • No floor build-up
  • Excellent heat transfer
  • less expensive as no plates required
  • Increased weight on the joists
  • Can be difficult/messy to install

Ideal Applications: Good heat conductivity, can be used when retrofitting when there are no fears of overloading joists.

timber straps with underfloor heating pipes between. Being covered by a dry screed mix

Spreader Plates

Spreader plates are ideal for underfloor heating wet systems on suspended floors. The void between joists must be insulated to minimise airflow to reduce heat loss. Plates are placed between floor battens or timber joists by the installer. Joists are notched to allow pipes to pass across the room at 1 end.

Spreader plates are made of aluminium due to its excellent thermal conductivity. The flat upper surface which is in contact with the floorboards applies heat evenly across the area. Plates are grooved with either 2 or 3 ridges which hold the heating pipes in place.

Key Features

  • No floor build-up
  • Lightweight
  • Quick installation
  • Cost of plates
  • Noise due to expansion and contraction

Ideal Applications: Perfect for retrofitting projects where floor height constraints exist and minimal disruption is desired.

spreader plate underfloor heating system

Spreader Plates – fit from below

When renovating the room below and the joists above are exposed, this provides the perfect opportunity to install underfloor heating on the upper floors. Fit from below aluminium spreader plates are ideal for installing underfloor heating in this instance. It doesn’t raise the floor height and no screed is required, thus being the most convenient solution for fitting heating between joists on any storey.

Each plate is secured to the existing flooring from below before pipe runs are then secured. Insulation wool is required to improve heat conductivity, placed below the plates before a new ceiling is installed. Each panel is 1000 mm x 250 mm to give an average spacing of 200 mm (between 400 mm joists). Single fit from below spreader plates are also available which hold one run of pipe. These can be used alongside a standard plate to increase pipework density and heat output.

Key Features

  • Don’t need to remove floor boards / floor coverings
  • Pipes accessible from below
  • Can be difficult to instal reaching above head height
  • Less efficient than other methods

Ideal Applications: Perfect for adding underfloor heating to upper floors.

Fit from below spreader plates underfloor heating system

Choosing the correct underfloor heating system is the first step to instating a wet underfloor heating system. Evaluate your floor type in each area of your home and choose the relevant system. If you are unsure which type will suit your project best or need a little information for your project give us a call.

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