Insulation in UK homes, as well as commercial and industrial premises, is on the rise. In part, this is the result of a government push for better energy efficiency. Installing insulation throughout different areas of your home has undeniable benefits, particularly lower energy bills, and more comfortable living quarters when the cold hits. The majority of homes have some sort of wall and roof insulation, as these are the areas accounting for over half of lost heat. However, an overlooked area is the floor. Here, roughly 15 per cent of heat is lost, depending on the floor type and materials, as well as the level of overall insulation. A biting fact is that over three-quarters of older homes lack any sort of insulation in floors, so suffer from higher bills and colder ambient temperatures in winter.  

Insulating Your Floor 

A large portion of heat escapes from an uninsulated ground floor. Though this might not be as much as wall or roof cavities, floors above unheated areas like garages will definitely feel the cold. Most homeowners first insulate walls and the roof. The next logical step is the floor. There are several insulating materials, like the popular rigid-foam PIR floor insulation boards, that help prevent heat loss, seal areas from drafts, and lower monthly or quarterly energy bills.  

Your choice of materials largely depends on the type of floor. These are either solid concrete walls seen in newer homes, or suspended timber floors in older houses. Older timber floors are easier to work with, and benefit more from installed insulation. For concrete floors, there are some added labour costs, and your initial investment is recouped over a slightly longer period.  

Insulating Suspended Timber Floors 

Timber floors consist of floorboards attached to timber joists. There are two ways to insulate a suspended timber floor, depending on whether you have access below or above the joists. It is easier to insulate from below, as this doesn’t require lifting the floorboards. Though mineral wool is the cheaper option, it needs to be at least 150mm in thickness to compare to the same thermal properties provided by 90mm of rigid foam boards. PIR floor insulation will give you the best results here, provided pieces are cut to fit precisely within joists, and any gaps sealed. Timber needs adequate ventilation, so do not block airbricks in outer walls. Insulating timber floors from above does take a little more work, including detaching the floorboards. For a detailed how-to guide in insulating suspended timber floors with rigid foam boards, see here.  

Insulating Solid Floors 

The benefits of thinner rigid foam insulation boards are more evident when insulating solid stone or concrete floors. Though these will retain heat better than timber floors, an added layer of insulation will mean less heat is needed to sustain comfortable dwelling temperatures, and therefore, lower energy costs. Rigid boards also allow for lower temperatures during the summer, and thus, prevent the buildup of moisture and mould. New properties allow for insulation to be installed under the floor and thickness is not an issue here. Existing homes, on the other hand, are insulated with floor insulation board under a layer of concrete screed and plywood or OSB boards on top, in effect slightly raising the floor. Floating floors, without the use of screed, are another way of effective insulation when renovating or retrofitting existing floors.  With better thermal retention for the thickness compared to other insulation types, and a high level of rigidity, rigid boards, especially PIR are the best options in such instances. If doing this as a DIY project, make sure to comply with current British Building Standards concerning ceiling heights.  

Top 10 Benefits of PIR Floor Board 

I’ve touched upon the high thermal retention, or R-values, of PIR floor insulation boards, as well as the ability to use thinner boards where space is restricted. But PIR boards also offer other advantages, compared to other rigid boards, and other insulation materials like mineral wool blankets and foam spray.  

• Polyisocyanurate, or PIR, boards have some of the highest thermal efficiency rates, coming close to phenolic boards, without the typically high prices 
• PIR can be optioned thinner precisely for this reason, and this also saves money. Thinner boards are cheaper and can be used in insulating floors in homes with restricted heights. As for comparison, EPS and XPS boards can be used in floor insulation, but need almost double the thickness for the same results. 
• The closed-cell structure, consisting of a combination of polymers, polyols and isocyanates, lends to several favourable physical properties. PIR is lightweight, weighing in at just 3.2 kilograms per square metre, so is also easy to lift and handle during installation. 
• PIR is extremely durable, keeps its structural stability throughout the lifetime of the building and lends its rigidity to other building elements.
• Boards don’t shrink or deteriorate over time. 
• PIR boards are resistant to pressure and impact. This makes them the best choice for roofing and floor insulation. The boards won’t bend or deform in any type of floor insulation and can withstand high loads.  
• PIR is resistant to humidity and moisture. Boards with aluminium backer and facer materials help wick away moisture and liquids, which also means they also retain their form in different weather conditions. This is especially useful in roofing applications.  
• PIR is fire-resistant. This is another selling point of PIR boards. It doesn’t catch fire, emit smoke, melt or drip. For this reason, it also qualifies for fire-safety standards. In flooring, this means PIR insulation will help in resisting the spread of fire to other elements in the building.  
• PIR floorboards are eco-friendly. It requires a lot less energy to produce and contains considerably fewer toxic substances than other insulation boards. 
• Boards come in the standard sizes of 1200 by 2400mm but differ in width. Thicker boards are naturally more expensive. They are easy to cut to shape, create little to no dust, and separate pieces can be combined with minimal effort. You can install them yourself, or have the work done by a pro. Look for British manufacturers of PIR floorboards from retailers stocking insulation solutions.