A Best Practice Approach To Insulating Suspended Timber Floors (2024)

FAQs

What is the best way to insulate a suspended timber floor? ›

Answer: Ideally a fibrous insulation such as mineral wool or sheep's wool performs best between timber because it will take up thermal movement and cut down air movement around the insulation. 'Thermal bypass' affects performance, so cutting out draughts is preferable.

Many suspended timber floor constructions have discontinuous insulation between the joists. That leaves an opening to improve moisture management and airtightness – by fitting a Tyvek^® membrane and carefully sealing the gaps and joints. Tyvek^® membranes are ideal for suspended timber floor construction.

Underlayment. Most homes with hardwood flooring use underlayment to add a layer of insulation between the subfloor and floor. So, materials that act as insulators, namely rigid foam, polyfoam, silicone, fiberglass, or rubber are used to keep the surface from getting cold in winter.

Insulating Suspended Floors From Above

If the cost and disruption of taking up floorboards cannot be endured, and there is no access to the space below the floor, then insulation must be done on top. The insulation must be thin to avoid affecting door opening height.

Now, when choosing the best floating floor insulation, you need a material that will not only control the heat movement, but that will also strengthen the entire construction. This is why we believe your best choice would be rigid insulation boards, which are among the most efficient insulation materials.

For warm climates, the U.S. Department of Energy suggests using R-11 (3½”) insulation under floors, while in cold climates, they recommend R-25 (6″ to 8″) insulation. This practical advice helps ensure energy efficiency and optimal comfort in your home.

The thermal performance of suspended floors can be very significantly upgraded by insulating and/or by draught-proofing.

Deflection or movement in suspended floors may be caused by inadequate joists or by joists at incorrect centres. Changes of use can result in increased loadings, particularly in older buildings. Excessive deflection can cause the outer walls to bow.

However, where there are suspended floors, carpets can be great for helping to reduce footfall noise. While carpet is not a good conductor of heat, it will let the floor breathe and air can permeate from the underfloor cavity through any gaps and then through the carpet.

With solid hardwood, since you'll be dealing with at-grade or above-grade installation, you'll likely have a plywood subfloor. Do you, therefore, need a moisture barrier under wood floors, even if you're installing over plywood? Although a moisture barrier is not required, we highly recommend using one.

Does insulating floor joists help? ›

Insulating in between your floor joists is one of the best ways to upgrade your home comfort and energy efficiency. Some homeowners worry that installing floor insulation will do more harm than good, but if the job is done well, you won't see any drawbacks.

The best solution is to insulate underneath your floor with a Polyester Underfloor Insulation and/or fill any cracks or gaps with UltraClear. This is where and how to start: Find out if you have gaps between your floorboards. Look for gaps between your skirting board and your floorboards.

An uninsulated ground floor can easily add up to 30 percent of the heat loss of a building – especially when the crawlspace is heavily ventilated. Why do you call a ground floor suspended? When the ground floor has a crawl space underneath the floor, beams or concrete slabs are suspended from wall to wall.

Complying with building regulations

The U-value is a measure of how quickly heat will travel through the floor. To achieve this standard, you will normally need at least 70mm of high-performance foam insulation, or 150mm of mineral wool, but this will vary depending on floor type, shape and size.

In order to prevent an excessive build-up of moist air in the underfloor space in a suspended timber floor, underfloor ventilation is necessary. An even distribution of vents will ensure the elimination of stagnant air pockets where moisture might accumulate.

Q: What are the drawbacks to suspended timber floors? They can tend to deteriorate more quickly as the timber can rot, so they need a little more maintenance than other flooring types. They can also feel a bit draughty which is why they need to be properly insulated.

Ventilation should be provided to precast and timber suspended floors. This is generally provided by ventilators on at least two opposite external walls, with air bricks properly ducted in accordance with Chapter 6.1 'External masonry walls'.