Regulation changes make a point about pitch roof insulation
Recent changes to the Code for Sustainable Homes have again focussed attention on the increasingly stringent demands which surround the creation of new homes. However they may also have helped simplify the choice of insulation, especially for pitched roofs, as Recticel’s Chris Hall explains.
As the UK focussed its attention on the General Election at the start of May it would have been easy to overlook the changes that came into effect regarding the Code for Sustainable Homes. However specifiers, contractors and other roofing professionals certainly can’t afford to ignore these changes.
One of the key differencesintroduced was the requirement for all new homes to now achieve a Level 3 rating under the Code. To put this into context, it translates into a 25 percent improvement over the current Building Regulation requirements for domestic properties and an even greater jump of 44 percent for public buildings. Energy efficiency is one of the key areas that are considered when a building’s Code level is being assessed. Overall environmental performance and levels of energy usage for items such as space heating are carefully examined and this creates the opportunity for roofing insulation to play a crucial role in helping a building achieve the best possible Code rating.
Limiting the amount of heat lost through the roof decreases the amount of energy used to heat the home and will help boost the likelihood of achieving a Level 3 rating. So it follows that simply increasing the insulation performance of the roof is a good choice to help meet the new Code requirements.
Insulation for pitched roofs
However some insulation products are better suited to this than others, especially where a pitched roof is involved. Of the different options available, installing a thicker layer of mineral wool insulation might be an obvious choice but it is not necessarily the best, particularly if you intend to use the loft space as part of the living environment. Closed-cell PIR insulation board installed in between and under the rafters is a better solution which helps maintain the potential for immediate or future use of the loft space as part of the living environment.
From an installation perspective, PIR insulation board is light in weight and along with its rigid construction this makes it far easier to handle and install into a pitched roof. A good quality PIR board will often have excellent compressive strength, and while we’re looking at practicalities it will create minimal dust, both when cutting the boards and when it’s finally installed.
Environmental and economic savings
PIR offers another far more important advantage in terms of insulation performance. A typical 200 mm layer of mineral wool can often be replaced by a thinner 150 mm layer of PIR board. This also offers the potential for shallower fixings and reduces unnecessary increases in rafter depth. The reduction in the amount of timber used then translates into to another environmental and economic saving.
Some of the better PIR boards on today’s market have also recently seen improvements to their lambda value. This achieves a better thermal performance whilst maintaining the original thickness specifi ed and can also create the potential for thinner boards if required. Let’s not forget also that PIR is far superior to mineral wool in respect to resistance to damage caused from rain or water. PIR insulation with its closed cell structure does not absorb water in the same way as products that have an open cell structure, such as mineral wool.
So if you’re used to specifying and installing open cell insulation such as mineral wool, the next time you’re faced with the new Level 3 Code requirements it might just pay to look at PIR as a different option – your project’s Code rating may depend on it!
