Radiant Heating Solutions can Design, supply and install a number of different types of underfloor heating solutions.
Most owner-builders now install underfloor heating into their homes.
How the system performs depends, to a great extent, on the floor construction. Concrete floors are ‘high mass’ and will act like a giant storage heater, staying warm for many hours without any heat source.
In contrast, a timber-based floor is relatively ‘low mass’: underfloor heating in a timber floor therefore tends to heat up (and cool down) fairly rapidly, more like a conventional radiator system.
Thermal mass is the ability of a material to absorb and store heat energy.
Installing into a Solid Floor (Types A,B,C & D as shown)
Most underfloor heating is In-screed heating. It is a direct acting system and is installed just before the contractor screeds the floor.
Screed or Concrete floor types can drive the highest output underfloor heating systems with lowest running costs
Traditional or liquid screeds options can be used
Fast to install - staple or clip rail system directly to insulation
Zero increase in floor height
Floor Type offers great Thermal Mass
Probably the most common of all the floor constructions that we supply underfloor heating systems for.
One of the major benefits of installing into this floor type is its compatibility with low temperature heat sources, such as ground or air source heat pumps. The pipe spacing can be reduced or increased depending on the heat loss of the building and the water temperature being supplied by the heat source.
With On top of the ‘slab’ or the block & beam you will need to lay some insulation. This is normally a high density board type such as ‘Kingspan’ TP10 or similar. Designed to prevent the heat from being lost downwards.
If being installed in a basement or ground floor, the floor build up would normally stop after the damp proof membrane had been installed. At this point the insulation for the underfloor heating would be laid and the vapour barrier would then be installed on top of the insulation. The pipes would then be clipped to it using a barbed clip pushed into the insulation from a clip gun.
Once the pipe work and manifold has been installed and pressure tested, the screed would then be laid. If using liquid screeds, then particular attention should be paid to ensure that the screed does not run between the boards and through gaps in the vapour barrier. The screed supplier will always advise you of any specific requirements for their products.
Installing into a Suspended Timber Floor – with NO Thermal Mass (Types E,G,& H as shown)
Joisted floors are suspended timber floors that use joists to support the floor deck. The underfloor heating system lies either between or straddling the joists.
This method is best suited to well insulated buildings that are using oil or gas boilers.
Water flow temperature is around 40°C – 60°C depending on how well the building is insulated
Often used on First Floors
Quick and easy to install with a fast response time
Can be applied to both new and existing buildings and installation can be relatively quick due to the use of Alluminum plates.
Note: These floor type cannot be used above any uninsulated areas such as a garage, without the correct thickness of insulation to comply with building regs.
Installing into a Suspended Timber Floor – with Good Thermal Mass (Type D as shown)
If you are wishing to use a Heat Pump for underfloor heating these considerations need to be made.
Thermal mass allows the water flow temperature to be much lower (30°C – 45°C) and still give out high energy performance.
The depth of the ridged insulation boards would be 60 - 100mm for ground floors (or any floor where the space below is unheated) and 25mm for first floors etc. A space of 20 – 25mm is left between the top of the insulation and the underside of the floor boards for the pipes and the sand/cement filling.
This is a just a weak semi-dry mix that has no structural strength. The additional weight on the joists is approximately 25kg/m2. You must design the floor joist to accommodate this extra load.
Note: The sand/cement filling can be omitted when using this floor type with oil or gas boilers. When using a sand/cement filling it must be allowed to fully dry before the floor boards are fitted. Failure to do this will result in moisture from the cement distorting and damaging the floor boards.
Installing onto an existing floor (solid or suspended timber) floating floor - No Thermal mass (Type J as shown)
A floating floor is a floor that does not need to be nailed or glued to the subfloor.
Used when putting underfloor heating onto an existing floor. This is a special type of system comprising of grooved insulation panels with foil diffusion layer.
The insulated panel is available in different thicknesses for floors that require a higher amount of insulation, and also with different pipe spacing for different outputs.
Existing floor (concrete of timber) in good sound condition
Insulation panel – 25 – 50mm (including pipe)
Sub-floor – Either timber floor boards or specialist solid floor panels
Floor covering - Stone/Tile, Timber, Laminate, Carpet on top of chip board flooring
The term floating floor refers to the installation method, but is often used synonymously with laminate flooring but is applied now to other coverings such as floating tile systems and vinyl flooring in a domestic context.
A sprung floor is a special type of floating floor designed to enhance sports or dance performance. In general, though the term refers to a floor used to reduce noise or vibration.
A domestic floating floor might be constructed over a subfloor or even over an existing floor. It can consist of a glass fibre, felt or cork layer for sound insulation with neoprene pads holding up a laminate floor. There is a gap between the floating floor and the walls to decouple them and allow for expansion; this gap is covered with skirting boards or mouldings.
Floating floors as used in sound studios can be either just larger versions of the domestic variety, or much larger constructions with slabs of concrete to keep the resonance frequency down. The manufacture of integrated circuits uses massive floating floors with hundreds of tons in weight of concrete to avoid vibration affecting mask alignment.
Floating floors are one of the requirements for the THX high-fidelity sound reproduction standard for movie theatres, screening rooms, home theatres, computer speakers, gaming consoles, and car audio systems.
While floating floors add to the appeal of a home, they are not recommended for areas that may get wet, i.e. bathrooms and near exterior doors.
Technique often used when putting underfloor heating onto an existing floor that already has insulation in it or where the space below is heated.
This is a special type of system comprising of insulated panel, pipe and heat diffusion plates. The insulated panel is available in different thicknesses for floors that require a higher amount of insulation.
Floor Insulation – what type and why?
On all ground floors and even raised floors where the space below is unheated, floor insulation must be used.
It is important to put down a good thickness of insulation when fitting Radiant Radfloor underfloor heating (UFH) pipe.
In a standard concrete floor expanded polystyrene (EPS) is placed below the concrete sub-base. This sub-base is often referred to as the oversite concrete base.
This EPS insulation will be just enough to comply with current building regulations.
However, with UFH the insulation should be to a higher thermal value because the floor will now be heated.
With normal heating such as radiators the floor temperature is around 19°C whereas with UFH the floor temp can be as high as 29°C.
This higher temperature leads to what is known as greater down losses. In other words, the floor is much warmer than the base below and so more heat will be lost downwards.
To prevent this waste of energy a better quality or thicker floor insulation is used. Furthermore, the floor insulation is now positioned above the oversite concrete base.
The reason for this is to reduce the overall amount of thermal mass to a manageable level. If the mass is too great (too thick) the floor will take a very long time to both warm up and cool down.
There are two main types of floor insulation for solid concrete floors, high density expanded polystyrene (HDPS) and foil or linen faced polyurethane (PU). Both of these are supplied in ridged sheets or boards.
For floor heating another requirement is the compressive strength of the board. When laying the pipe for the UFH the insulation boards are walked over many times. Weak boards such as normal ESP and some types of PU will crush making the floor uneven. Some are even too weak to hold in the pipe clip or clip rail in place.
Radiant always recommend using a very ridged board such as Kingspan TF 70 or similar. If we are designing the UFH scheme, we will state the required thickness and type of insulation board in our quote.
When using a heat pump it is very important to use a minimum thickness 0f 70mm (100mm is recommend if practical). This is because the water temperature of the UFH pipes is very low and down losses have to be virtually eliminated.
How thermal mass works
Thermal mass acts as a thermal battery. It absorbs heat slowly and releases it slowly, keeping the house comfortable.
When the mass is up to temperature it requires very little energy to maintain that temperature.
Thermal mass is therefore ideal for heat pumps because it smooths out the peaks and troughs normally associated with heating a building.
Floor Type A: Solid floor using barbed clips
Floor Type B: Solid Floor using clamp track
Floor Type C: Solid floor using foil insulation and clamp track
Floor Type D: Solid floor using floor timber battens
Most common floor construction for a solid floors including block and beam. Heat outputs up to 120W/MT² are achievable and ideal for low flow temperatures.
For Installations where standard barbed pipe clips are
unsuitable due to the insulation product used on the floor, Clamp track can used to ensure that the pipe is secure well prior to the screeding process.
Ideal for installation where the floor insulation has been
Installed below the subfloor or for renovation where floor
heights are limited.
Solid floor construction with battens for fixing wood floor
finishes. A ‘Pug’ (6 : 1 semi dry sand and cement) screed can
be used as the battens become the load bearing part of the
floor construction. Also only having a low water content in the screed helps create a good environment for the timber finish.
Floor Type E: Suspended timber floor with foil insulation
Floor Type H: Suspended timber floor with cross battens
Floor Type G: Suspended timber floor with spreader plates
Floor Type D: Solid floor using floor timber battens
Suspended timber floor construction using foil insulation and cross battened is ideal when the finished floor level can be lifted by 25mm and the floor joists cannot be notched like when using ‘I’ beams and dramatically shortens installation times.
Suspended timber floor construction using aluminium spreader plates is a option for a high output floor if a Pug screed cannot be used because of the extra weight.
Suspended timber floor construction using foil insulation for
a light weight option over areas which are heating. Uses a
slightly lifted flow temperature compared with solid floor.
Suspended timber floor construction using solid floor insulation
and a Pug screed Infill. Ideal for use with renewable technologies where it is essential to maintain low circuit temperatures also aids with sound proofing. Typical weight is around 25KG/MT²
Floor Type J: Suspended timber floating floor panels
Suspended timber using floating floor panels onto existing floor or when a deck has to be put down at a early part of the build. Gives lower thermal conductivity and better sound proofing than foil insulations.
Handy 1 page PDF of the floor types for you.