Posts tagged ‘Building Control requirements’
Thatching Advisory Services (TAS) have received notification that both their Thatch Fireboard System and Thatch Firewall Membrane System has been approved and added to the Local Authority Building Control (LABC) Registered Details database. LABC registration is a one-off certification process proving compliance with building regulations and standards across the UK.
The registered details database contains various products and systems, which once certified, are accepted by LABC building control surveyors in over 300 local authorities across the country. This assures the whole construction industry that a product or system has been rigorously checked by LABC surveyors.
Full details on both systems can be viewed via the LABC links below:
There are approximately 60,000 thatched properties in the UK, of which 50-80 suffer a serious fire each year, most of which are completely destroyed. 90% of the homes struck by thatch fire have a combination of a wood burning stove either a flexible chimney liner or no liner at all.
Chimneys should be checked to ensure the brick or stonework is in good condition. Old or poorly maintained chimneys with loose or missing bricks & mortar and not lined, could allow hot gases and smoke to escape into upper rooms, the loft space or directly onto the thatch. If re-thatching works are taking place and the thatch around the chimney stack is removed, the thatcher will be able to advise on its condition.
Ensure chimneys are regularly swept by an experienced and qualified chimney sweep. This normally needs to be done at least twice a year, however if the chimney is used frequently during the winter period then additional sweeping may be required. Your sweep will be able to offer you further advice. Many chimney engineers and other specialist companies offer a CCTV survey, this is recommended to check the internal condition of the flue. Again check with your property insurer because some of them have a list of approved companies.
A number of thatch fires occur as a result of old or inappropriate flue liners, therefore chimneys serving either an open fire or multi-fuel appliance should be suitably lined. Contact an appropriate professional body such as HETAS so a registered chimney engineer can review the liner (if already installed) to ensure it is fit for purpose for the type of appliance or fire in use.
An engineer will also be able to advise on the condition of the liner and recommend on how often it should be checked. If you are considering installing a wood-burner or similar, again contact HETAS who will advise on the most suitable appliance and liner for the property.
U-Values & Condensation in thatch
Modern living under thatch has changed in the last 10 to 15 years, with the introduction of modern central heating, double/secondary glazing, power showers and more home owners wanting fully vaulted ceilings. In addition, the requirements and associated recommendations from Building Control and insurance companies see the requirement for fire barriers and increased levels of insulation to be installed within the roof structure.
All these areas can have an effect on the performance of thatched buildings, therefore all components of the roof structure need to be built into U-Value calculations/reports.
U-Values are expressed in units of watts per degree of temperature difference W/m²K. Overall U-Values will vary according to actual thickness and density of the thatch. For example:
- 300mm thickness of Water Reed – 0.29 W/m²K
- 300mm thickness of Long Straw – 0.23 W/m²K
For comparison, the standard in Part L of the Building Regulations (2010) for replacement roof insulation at rafter level is 0.18 W/m²K.
A suitable insulation product to help achieve a U-Value of 0.18 would be Thatchbatts® as they are non-combustible, high density slabs which also offer additional protection in terms of fire resistance.
It is widely accepted in the construction industry that in addition to sufficient levels of insulation, vapour control layers are required to control vapour and reduce the risk of condensation. A correctly fitted vapour check will also play an important part in the way the building continues to perform in the long term.
Bespoke U-Value & Condensation Risk Analysis reports can be generated for thatched roofs and will take into account the design and construction, type of materials used and location within the country.
See the Thatching Advisory Services website for further information and product details.
Thatch is enjoying a resurgence. Architects, builders and owners increasingly acknowledge the advantage of thatch insulation and aesthetic qualities. Recognising this increasing popularity the eight building control authorities throughout the county of Dorset reviewed current building controls for a thatched roof.
The result of these controls will:
- Either protect the main structure of the building if a fire occurs.
- Or provide better protection for the roof members if a fire occurs.
- Require an acceptance to treat the thatch as sacrificial in a fire.
Companies specialising in thatch roof insurance welcome the “Dorset Model” and recognise that it will reduce the premiums paid.
Thatching Advisory Services (TAS) were recently involved in an unusual but unique thatched project in Liverpool.
The Lighthouse in Formby saw the majority of the building, including the sides being completely thatched.
The project saw TAS working closely with the main contractor – Kirklake Developments and D-K Architects to advise on and provide the most suitable and comprehensive fire barrier system for the building.
After consultation and submission of test reports, it was deemed that the newly designed and tested ‘TAS Thatch Fire Membrane System’ would be the most suitable system to use for the project.
The TAS Thatch Fire Membrane System, which incorporates Thatch Firewall Membrane and Thatchbatts® is tested to BS476: Part 3: 2004 and CEN/TS 1187:2012, test 4, as recommended by Building Control – Approved Document B.