Insulation is one of the most important aspects of any home construction or renovation project. Though adding insulation to the roof space and walls during construction is standard practice for architects, designers and builders, insulating the subfloor area remains one of the most overlooked areas for new and renovated homes, creating cold, draughty and uncomfortable spaces.
The floor structures of many new homes and extensions consist of a suspended floor with subfloor space beneath. In the absence of insulation beneath the floorboards, thermal bridging will create a direct link to the external temperature beneath the floor and outside the home, causing undue discomfort to the occupants, and requiring excess heating or cooling energy within the home.
While carpets or rugs may provide a small level of protection from the outside cold in winter, owners of these homes will still be pumping heat into their homes, only for it to escape by conduction through the floor and by convection (air leaks) through cracks in construction surrounding the flooring.
By specifying subfloor insulation, architects, designers and builders can add a little luxury, comfort and energy savings for their clients.
Subfloor insulation solutions
Subfloor insulation helps provide a continuous layer of insulation around the entire building envelope. A bare timber floor on joists with open subfloor and no insulation will have an effective R-Value of R0.3 (heat flow down by conduction); when carpet is placed on the same floor, the R-Value may reach R0.5. In modern homes external walls are likely to achieve R2.5 while ceilings/roofs achieve a total of R4.5; this means the uninsulated floor can conduct 5 times more heat than the wall and 9 times more heat than the roof/ceiling.
Thermal comfort
Bradford Optimo helps reduce thermal bridging through the subfloor of a home. Optimo is best installed during construction using Bradford’s patented Optimo saddle to hold the insulation securely in position between the joists and hard to the underside of the floor, prior to laying the floor substrate.
Bradford Optimo is supplied in R2.1 or R2.5, Optimo saddles are placed over the floor joists and Optimo glasswool batts are placed between floor joists resting on the saddles.
When the carpeted floor in the above example is installed using Bradford Optimo, the total R-Value will range from R2.6 to R3.0 (depending on the Optimo product). The home envelope now ensures winter warmth is contained and summer heat excluded.
Considering ceilings are roughly the same area as the floor, aim for a total floor R-Value, which is at least half of the total roof/ceiling R-Value to optimise the thermal envelope.
Optimo insulation helps keep the internal temperature of a home more stable by maintaining the flooring at the internal ambient temperature rather than conducting the outside temperature to the inside of a home. Optimo also helps reduce air draughts through the floor and perimeter.
If you’re designing or planning a new home with raised floors, specify Bradford Optimo to add that extra luxury, comfort and energy savings for your client.
Technical project support
Consult with the CSR Bradford DesignSmart team for assistance with installing Optimo insulation for any of your projects. As experts in building insulation, the DesignSmart team has a wealth of construction experience and utilises industry-leading building science research for acoustic, thermal and fire performance. The Bradford team can provide assistance with project-specific support – system selection; value engineering challenges; specification documentation; system design detailing; and product installation and certification.
