The Best insulation for roofs


There are a number of insulation products on the mark today. But what is the best insulation for roofs? This is a difficult question and there are so many different applications application. And certain products suite certain products more than others. In fact, there are a number of factors to take into account to come to the conclusion as to what is the best insulation for roofs.

What is The Best Insulation for Roofs

We will go through some of the major roof insulation products and look at the pros and cons of each to see what is better in the end. You make the decision based on what you believe to be the best insulation for roofs. The thing to take into account is the effectiveness of Roof Insulation lifespan and health and safety of family and loved ones.

Isotherm Roof Insulation

Isotherm is a roll form insulation and is supplied in a number of different thicknesses as well as different widths. The recommend Isotherm product for the Western Cape is the 145mm Isotherm. This insulation is SANS compliant as per the new legislation. Isotherm is also manufactured by a stock market listed company.


  1. Isotherm Roof Insulation is Dust free ideal for families with allergiesisotherm best insulation for roofs
  2. Allergy-free Isotherm Insulation ideal for families with allergies.
  3. Soft to touch and smooth no itch
  4. The Isotherm is SABS approved
  5. The great Isotherm thermal insulation properties.
  6. Cooler in summer with Isotherm.
  7. Warmer in winter with Isotherm
  8. Save money on energy
  9. Reduce noise levels coming through the roof great acoustic properties.
  10. The Isotherm does help with the spread of mould on the ceiling
  11. Great fire rating tested by TIASA isotherm will not sustain a flame
  12. Isotherm thermal insulation for roofs has a great R value that exceeds the recommended R-value for the Western Cape Region. The 145mm Isotherm is SANS compliant for the Western CAPE
  13. In fact, Isotherm Insulation retains very little water and the little that it does retail will dissipate on the next hot day. Isotherm does not rot.
  14. We have our Isotherm rolls cut to size before we arrive on site. As we have a 750mm wide roll and a 1200mm wide roll. So there is a roll for tiled roofs as well as a roll for sheeting roofs.
  15. In fact, Isotherm roof insulation does not collapse over time.

Isotherm Insulation 30 Year Guarantee

  1. Isotherm 30-year manufacturer guarantee.
  2. In fact, Isotherm Insulation is probably the most eco-friendly insulation product in the world. Isotherm is manufactured from recycled plastic bottles PET. and in fact, the isotherm insulation is itself recyclable. As the Isotherm is manufactured in all three major cities there is not fuel wastage getting the insulation to the different provinces so there is a very limited carbon footprint.
  3. In fact, Isotherm has our highest referral rate of all insulation products that we use.
  4. FINALLY, CAN YOU LEAVE A CHILD TO PLAY WITH ISOTHERM INSULATION? YES, YOU CAN IT IS THAT SAFE. In fact, this is what makes Isotherm one of the best insulation for roofs.


  1. The Isotherm Ceiling insulation is not compressed packed. So transporting stock to sites means a little more work. On the other hand, this gives the insulation a far better recovery rate,
  2. Packaging is a little on the weak side if rolls are thrown out of high truck packaging tends to pop.
  3. Isotherm is difficult to cut for the DIY guy. However, if he has a standard tiled roof we have specific rolls pre-manufactured so there is no cutting.
  4. The Isotherm fire rating is not very good with a class BB 1/2 meaning that the insulation will sustain a flame when there is something burning, however, the isotherm will stop burning when the flame stops.

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Aerolite Roof Insulation

Aerolite roof insulation has been on the market for nearly a century. The Aerolite ceiling insulation is probably one of the most installed insulation products worldwide.  In fact, Aerolite is manufactured in South Africa in a number of thicknesses however the 135mm Aerolite is SANS compliant for the Western Cape region. Manufactured by stock market listed company.


  1. Aerolite Insulation is SABS approved.Aerolite best insulation for roofs
  2. Aerolite thermal insulation properties are great.
  3. Cool in summer with Aerolite insulation.
  4. Warm in winter with Aerolite Thermal insulation
  5. The Aerolite 135mm has great NRC 1.2 noise reduction properties. this insulation is very popular for soundproofing.
  6. The lifespan of Aerolite is 15 to 25 years.
  7. Aerolite has a great fire rating Aerolite will not burn.
  8. The Aerolite Roof Insulation will save on energy
  9. In fact, Aerolite is also regarded as an eco-friendly insulation as it is manufactured from recycled glass bottles and naturally occurring silica sand.
  10. The Aerolite is SANS compliant as per the new legislation.
  11. Aerolite insulation does not absorb water. In fact, the water from leaks or geyser burst will run straight through the insulation and you will very soon see that you have a roof leak and can the make plans to repair before major damage. Aerolite is also one of the best insulation for roofs.


  1. Aerolite being fibreglass has the itch factor and some consumers don’t like this especially when they have to work in the roof space. In fact, we find that contractors working on the roof will move the Aerolite to work on whatever but not replace it again because of the itch. And I must be honest the itch can be a little uncomfortable but a hot bath or shower will reduce this in no time.
  2. The Aerolite dust in homes with downlights can sometimes affect people with allergies.
  3. Aerolite must be cut on site in the roof as we only have 1200mm rolls.
  4. Resin binders in Aerolite reduce the lifespan, however, this roof insulation has a long lifespan.

Cellulose Fibre Insulation

This insulation type is a finely shredded paper dust type roof insulation that is blown into the roof space with a pump that sucks the ceiling insulation into the roof space. The operator will then move from line to line pumping this paper dust into the roof space. Many of the manufacturers of these type of insulation products are not stock market listed companies and often operate out of smaller factory units as the product is reasonably simple to manufacture.


  1.  Cool in summer
  2. Warm in winter
  3. Reasonable NRC noise reduction properties.
  4. Save energy with Cellulose fibre insulation.
  5. Very cost effective to install.


  1. Manufactured from recycled newspaper some regard the insulation as eco-friendly. However many believe that our forests are in danger a paper becomes a sought-after commodity. In my opinion, this paper could be put to better use in newsprint etc.
  2. The cellulose has a host of chemicals up to 25% added to give some sort of fire retardant properties as well as chemicals to prevent rats from nesting in the cellulose.
  3. Of all the insulation products that we supply and install this is one product, we will never install as we are not happy with the chemicals in the insulation.
  4. Fine dust type Cellulose insulation will absorb water in the roof space if you have a roof leak. In fact, we have removed this paper dust like insulation with our massive vacuum machine designed to remove the blown in paper insulation or cellulose.
  5. Ceiling collapses as a result of the fine paper dust absorbing water is heard of very often. Especially here in the Cape with our long winters with rain and the wind.
  6. Not ideal for people with allergies because of the paper dust.
  7. Fire retardant properties seem to dissipate with 5 to 10 years and can potentially leave you with a problem if there is a fire in the roof. As paper insulation tends to either burn or keep on smouldering.
  8. Insulation movement in some homes where we have removed the insulation. We find that there is a huge heap on one side of the home and almost no paper on the other side. This is because South Africa homes are designed to breathe and with the strong winds that we get in the Cape. The insulation tends to blow to the opposite side. THIS LEAVES YOUR INSULATION PROPERTIES COMPROMISED.

Is It Possible To Get the Correct Thickness when Spaying In Cellulose

  1. However, the one factor that always bugs me as a person that would rather over specify than under specify is as follows. When spraying the cellulose fibre insulation into the roof space how is it possible with the naked eye to decide that you have now got the correct thickness. Surely the looking at the beams as a reference point to what you think is 135mm thick does not mean the product is 135mm thick in the centre.
  2. In homes tested for thickness before we remove we have found differences of up to 70 mm. Because the cellulose is blown in there is no direct thickness it is just a thumb suck.
  3. In the USA it is recommended that 20% more paper insulation must be installed because the insulation sags with time.
  4. If the paper gets slightly wet but not enough for ceiling damage this can and will cause mould build up.
  5. Some Cellulose suppliers have a 10-year guarantee and others even higher. This is odd as the moisture in the cape region dissipates the fire retardant chemicals in a short period of time.
  6. If your ceiling cornices pull away from the wall and cellulose lands on the floor of your home. This could be a danger to little babies crawling around on the floor. As we know they will lick or eat anything they find. And the same applies to our pets.

So What Then Is The Best Insulation for Roofs

This is a personal choice as we all have ideas on what we believe is best. The idea is to give the advantages and disadvantages so you can make the right decision on what the best insulation for roofs are. What is an advantage for some might be a disadvantage for others in the quest for best insulation for roofs? There are also a number of other insulation products on the market that I would not even consider putting into the category of best insulation for roofs.