Building Regulations: Information Sheet

“Where the area of the roof removed is in excess of 25%, and the insulation does not meet minimum standards, then the roof insulation needs to be upgraded. A Building Regulation application would need to be made, even if the work has been carried out in an emergency.“ Extract from T&M BC Guidance Leaflet 8.

The Government is keen to reduce the energy consumption of all buildings by encouraging us to improve the amount of insulation in our houses. To achieve this goal, it has introduced legislation that insists that if a householder renews his roof covering, additional insulation must be added, if there is little or none there already*. Furthermore a Building Regulation application for the proposed work needs to be made.

The most practical method of notifying the Building Inspector is by Building Notice, which can be served as late as 48hrs before works are started (the Local Authority fee to apply for a Building Notice is £120 + VAT (for works up to £ 2,000; and £190 + VAT for works up to £ 5,000).

A significant improvement in the thermal performance of a Flat Roof will not only improve the comfort of the rooms beneath, but also result in a reduction in fuel costs to heat that room.

Upon completion we will provide the customer with a Certificate of Compliance detailing the works that have been carried out and the construction.

* The Building Regulations Part L, Table 5, states that where technically, functionally and economically feasible, an existing Flat Roof that does not achieve a U Value of 0.35 needs to be upgraded to a U Value of 0.25. It further explains that a reasonable test of economical feasibility is to achieve a simple payback of 15 years or less (see SAP calculation right).


Sample SAP (Standard Assessment Procedure)
Calculation; Energy Rating

Assuming an existing 36 m2 Flat Roof with a 100mm fibreglass quilt insulation in the roof void, being upgraded with an extra 100mm of PUR roof insulation. We would expect a saving in heating fuel of approx £33 per annum.

The total saving, based on a simple payback over 15 years would be 15 x 33 = £ 495

The typical cost to upgrade a flat roof of this size with Vapour barrier, Insulation, and increased fascia, would be £1700.

We can therefore argue a case for this not being financially viable, although as mentioned previously there are several good reasons to upgrade insulation;

Comfort in winter; the room will feel warmer in the winter
Comfort in Summer; the room will feel cooler in the summer
Noise; insulation will reduce the transmission of noise through the roof
Environment; Less energy will be required to heat the room; your carbon footprint will reduce.
Cost of Heating; Less energy used = less cost
Home Resale Value; with the advent of the new Home Information Packs legislation (HiPs); when you come to sell your property, any works carried out by you whilst in occupation will need to be disclosed to the purchaser. You will also be asked to what standard the works were carried out. A new well insulated roof will give the purchaser a greater feeling of value / quality
Energy Rating; when you sell or rent a property, you will have to provide an Energy Performance Certificate, this document gives an energy rating for your property….. it will be more favourable if you have upgraded the insulation.

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