Insulation and underfloor heating - April 7, 2014 by Anna

Undefloor heating insulated living room

In these days of rising energy costs, it makes sense to install as much insulation in our homes and offices as possible. The correct type can help keep energy costs down plus waterproof and help soundproof a room. Insulated floors typically also reach desired temperature up to 7 times faster than those without depending on the type of heater, sub-floor and insulation levels.

So, in this article we aim to answer these questions you might be asking yourself:

  • When should I use insulation with underfloor heating?
  • What are the different types available?
  • In what situations is it not required?
  • How should it be correctly installed?

When should I use insulation with underfloor heating?

Whether you are opting for a hydronic or electric underfloor system, in most cases you should consider insulating. We all know heat rises but heat radiation can also be absorbed by materials such as screed or concrete in a subfloor. This absorption will lengthen heat-up times and increase energy consumption. It’s a good idea to opt for the maximum amount your budget and overall floor height will allow as this will improve energy efficiency and reduce running costs.

What are the different types available?

There is a wide range available for electric and hydronic heating systems. They come in different materials, finishes, thicknesses, sizes and strengths. The type of heater you have, the situation it is installed in and the budget you have, will all have a bearing on the style you need. The main type suitable for electric installations is made of polystyrene sandwiched between a cement polymer fibreglass mesh which is called insulation board. When using a foil heater product a specially designed foil backed flexible polystyrene roll is advised.

The hydronic installations are more suited to the PIR foam products, one with a foil layer both sides, the other with an aluminium grid on each face which aids with final pipe fixing. both are available in 25mm and 100mm depths and have a BRE rating of A.

In what situations is it not required?

When fitting a heater on an upper plywood floor where the lower floor is already being heated, insulation may not be absolutely necessary. Adding it however, will allow faster heat up times and therefore save energy costs.

How should it be correctly Installed?

Not all insulation is the same, especially the board type. This must be a suitably coated product to stop the tile adhesive unsticking, which could lead to inefficiencies in performance. When laying the boards onto a concrete or wood floor, the joints must be staggered. A flexible adhesive must be used to fix them in place and the board joints taped over with a glass fibre tape. On wood floors or walls, further screw fixings with washers is required.

The foil heaters have a specially designed foil backed polystyrene layer that sits foil down on the subfloor. Self-adhesive overlap strips that connect the segments create a waterproof barrier and no adhesive is necessary.

Always refer to the manufacturers installation instructions that will accompany the heater as installation differs from one type to another.


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