The Regulations surrounding Loft Insulation has increased every decade since the 1970's. Therefore, if your Loft Insulation is over 10 years old, the chances are that is does not meet current Regulations. The current Regulations are 250mm to 270mm of thickness. The long term benefits of good insulation are well documented. It assists in keeping your property warmer and therefore saving money on the cost of energy (which will only increase with time). So, your energy cost savings will also increase in time.