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Flat Roofing Insulation.Insulation.Insulation.

What is Part L Regulation

Part L is the section of the Building Regulations relating to thermal efficiency standards and affects insulation and heat loss. The Part L Regulation is renowned for being a complex set of requirements, particularly with the amount of revisions it has seen over the past six years. The 2013 changes will be the third of four planned revisions between 2007 and 2016 to help implement the zero carbon homes standard for which Government has committed to. The 2013 amendments to Part L contain three key changes: Energy Performance Certificates, major renovation of existing buildings and the analysis of high-efficiency alternative systems. The latter are the two most significant changes for contractors.

Major renovation of existing buildings

This is probably the most significant change to Part L for roofing contractors. The amendments give clarification on the major renovation of existing buildings and how much of a ‘thermal element’ must meet the Part L requirements when it is being replaced or renovated. For the purposes of Part L, a thermal element is a roof, wall or floor which separates a heated dwelling from the outside. Any unheated part of a building is exempt from Building Regulations.

The 2013 amendments

Any renovation that accounts for either 25% or more of the total building envelope or over 50% of an element’s surface means the renovation of the whole element must comply with Part L thermal requirements. For example, if more than 50% of the existing roof is being repaired or removed then the insulation for the whole roof needs to improve on the relevant U-Value as stated in the Part L requirements.

There has been a lot of confusion about what types of renovation need approval under the existing Part L regulations. So to clarify this, renovation of a thermal element can mean: – Adding a new layer, i.e. cladding or rendering an external wall – Replacing existing layers, i.e. stripping down a roof to rafter level and replacing the tiles, taking cladding off a wall down to brick or block work and then re-cladding and replacing the waterproof membrane on a flat roof. So if a contractor is renovating or replacing more than 50% of a thermal element Part L compliance will be required.

The importance of ventilation solutions

The risk of condensation can increase with the use of insulation, so to avoid any condensation due consideration should be made to ensure compliance with BS 5250 (Code of practice for the control of condensation in buildings).

Warm Roof


What happens if a roof doesn’t comply

If you view various web sites such as NRFC or CompetentRoofer they state you, the contractor or both can be fined up to £5000.00. I personally do not believe any such fines will ever be issued and these comments could be viewed as scare mongering, although this cannot be guaranteed and governing bodies as reputable as the NRFC would not make this statement if we’re not true. The fact is there are many 1000’s of roofs have been installed and are none compliant due to the total confusion of the Regulation.   The time has come to be compliant as the problem will arise when a property is sold and the relevant paper work is not in place. It could be like trying to sell a property without a Fensa certificate for double glazing.

Can the Part L Regulation be avoided

No, any avoidance is at the property owners own risk, although if you have the roof surface overlaid the roof does not have to comply.

Do I have to insulate my roof

In the Part L document page 23 states if there is 100mm of fibre type insulation i.e. a Rockwool type product (or an equivalent resistance) and if it undamaged and is not being removed as part of the work the roof will comply. The homeowner can opt out if it can be proved that the payback period will be more than 15 years or the work is not technically feasible.

Cold Roof