What is an R-Value?

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Insulation R-Value

Safe-R Explains Insulation R-Values

Insulation effectiveness is measured by its R-value. R-values measure insulation’s thermal resistance or how well it holds back heat. The higher the R-value, the better.

An R-value is a unit of thermal resistance for a particular material or assembly of materials . The R-values depend on a solid material’s resistance to conductive heat transfer. For loose or porous material, the R-value accounts for convective and radiative heat transfer through the material. However it does not account for the radiative or convective properties of the material’s surface, which may be an important factor for some applications.

Different insulation products have different R-Values as some insulation materials insulate better than others. Where you live will make a difference on which product you should choose and the total R-Value required to give you the best result.

The various areas of your home require different levels of insulation which is why many products have very different R-values. It’s best to speak to a professional about your property so they can advise you on the right product to choose for your home.

If you are going to do your own assessment or installation use the following advice

Safety First!

Before inspecting the insulation make sure that the area is safe.

Things to do

  • Read NZS 4246 – it’s free to access through EECA’s Energywise website.
  • Make sure the space is safe before you enter it. If you are entering the subfloor, particularly if it has foil, turn the power off at the mains to reduce the chances of electrocution – see the New Zealand Electrical Code of Practice, NZECP 55, for more
  • Take safety precautions – wear safety equipment, including gloves, dust mask, overalls, protective eye and
  • Be careful when using ladders – see this factsheet from ACC for advice on how to use them
  • Make sure that someone is nearby and able to assist if you need
  • Stand on the framing when you are moving around the roof space to avoid damaging or falling through the
  • Make sure the required clearances are in place for items that get hot, such as downlights, downlight transformers and flues. Ensure that open downlights are free of potentially flammable debris such as loose fill insulation – if you find some debris, call a qualified
  • Get a professional installer in if you have any doubts about the existing insulation or whether insulation can be installed safely and
  • If a professional installer installs new insulation, ask for a certificate or similar to show that they have installed it in accordance with the RTA R-value requirements. Keep this with your maintenance files.
  • If you’re doing it yourself, install it according to the instructions of the manufacturer and NZS4246

Things not to do

Don’t touch foil without turning off the power at the main switchboard – but proceed with caution, as in some instances the foil may still be live – see NZECP 55 for more information.

Don’t enter hot roof spaces – wait until it’s cool, and take a water bottle with you. Take frequent breaks out of the roof space.

Stay out of spaces where there are known health and safety hazards – e.g. asbestos dust, poorly installed electrical wires, or sewerage contamination. Get these sorted out first.

Don’t go into spaces that are too small or hard to exit safely.

Don’t fill required safety clearances, e.g. around downlights, over downlight transformers, or around flues or chimneys.

Don’t tamper with the electrics – if you think you’ve damaged something or a wire comes loose, call a licensed electrician.

Tips

  • To improve the performance of the total R-value you may wish to consider changing older downlights. Many modern downlights allow insulation to be fitted right up to them, and others even allow insulation to be put over them. Seek advice from a licensed
  • Check the price per square meter of insulation before you buy. You may be able to get a product with a higher R-value (higher performance) for less than one with a lower R-value.
  • Remember it is often cost competitive to get a professional installer to do the installation for you due to their ability to bulk purchase

Call us today on 0800 267 992 to speak to one of our friendly insulation experts or read more here