Does roof insulation work? Very good question – of course it works, to a certain point or should I say to a CERTAIN DEGREE.
Home comfort is the consensus for ceiling insulation in both summer and winter.
The concept for ceiling insulation is to stop the thermal rays of the sun entering the home in summer and for the extreme elements of winter from entering the home, as well as to keep most of the heated air from inside the home entering the roofspace.
HOWEVER, AFTER A FEW DAYS IN SUMMER OVER 28°CELCIUS, THE R VALUE OF THE CEILING INSULATION BECOMES COMPROMISED and excessive heat within the roofspace is allowed to radiate down into the home.
In winter at least 25% of home heating is lost to the roofspace – this can cause massive condensation problems.
The answer to all the problems of over insulating is for an effective roof ventilation system, an effective roof ventilation system will work with or without insulation see Blog on this site “Does Roof Ventilation Work”.
For a metal roof we recommend R4 insulation on the ceiling, with a blanket insulation under the roof sheet and an effective roof ventilation system to complete the hat trick. For a tiled roof we recommend R4 ceiling insulation and sarking only on 15° or lower. Any pitch above 15° is a total waste of money and rather than keep the heat out sarking will only help keep it in. Whether you sark or not you will definitely need an effective roof ventilation system.
We suggest at this point you should look at a Blog on this site “Warning Read Before You Design Your Next Housing Project” this and other blogs on this site will inform you of the pitfalls of over insulating without effective roof ventilation.
We like to share our experience of almost 60 years in the roofing industry, we have seen all the pitfalls and horrible truths that can happen within the roofspace.
Any reputable insulation company will recommend some form of roof ventilation.