NAMM are aware that attempts have currently been made by a company with ulterior commercial interests to discredit the NAMM Stability Device Accreditation. To set the record straight, NAMM have published the attached document, also drawing attention to the fact that video recordings of public demonstrations have been published where attempts to discredit NAMM accredited devices have been made. These tests did not install stability devices in accordance with the manufacturer’s instructions, or record device and test memorial dimensions.
The safety parameters established by NAMM and British Standards 8415 coupled with the NAMM accredited stability device manufacturers designs have resulted in no recorded cases of injury over 20 years, since the introduction of then NAMM Code of Working Practice requirements.
The National Association of Memorial Masons (NAMM)
Anchorage System Verification in accordance with BS 8415 Annex F
Background Information
In 1995 the National Association of Memorial Masons became concerned with the safety of old memorials. This followed deaths in 1995 in Derbyshire and Liverpool and a serious injury at Burnley involving unstable 5ft high, old memorials. A further fatality occurred in Harrogate in 2000.
Back in 1995, NAMM took the decision to commission a report on memorial safety from John Knapton, The Professor of Structural Engineering, University of Newcastle upon Tyne.
Following a series of practical tests, Professor Knapton published his recommendations 29th June 1995. Based on his report, members of the NAMM Technical Committee designed and tested a NAMM stability system. It was decided to use a test area at the Towcester Road, Northampton Cemetery and employ The John Parkhouse Partnership (JPP) as independent structural engineers. Since this time, all NAMM testing has been witnessed and recorded by Mr Nigel Thornton B.Sc (Hons) C.Eng MICE CMHT FGS. Whist NAMM recognised that stability devices could be independently tested at suitable independent establishments, because of the rigorous procedures, stability device manufacturers decided to seek NAMM accreditation. NAMM accreditation is only available when device performance is evaluated and witnessed by the NAMM appointed independent structural engineer.
The soil classification at the Northampton test area is defined as “medium sand and gravel” by Mr Thornton, of JPP, a Fellow of the Geological Society.
NAMM Accredited Stability Devices
Details for the NAMM stability device accreditation system are available from NAMM, but summarising there are 2 systems.
Continued……….
The Rigid System
A force of 100 kg is applied for 1 minute, the force is gradually increased and maintained at 150 kg for a further minute. Devices which meet this requirement without sudden collapse are recommended for accreditation.
The Collapsible System
A force of 100 kg is applied for 1 minute, the force the gradually increased and between the force of 100kg and 150 kg the system is permitted to gradually bend until it deflects to a safe 30 degrees from the ground level. A sudden collapse is deemed as a failure.
Tests are repeated with a backward and forward force applied, all structural elements and dimensions are recorded, but in particular the diameter of the stainless steel stability device and the diameter of the foundation and memorial base holes are recorded. In addition to the independent structural engineer overseeing, recording and witnessing the tests, 2 representatives from NAMM are present. The published test results are considered by the NAMM Technical Committee and subject to meeting the published requirements, accreditation is granted. It is a condition of accreditation that a device must be used in accordance with the manufacturer’s instructions and dimensions recorded at the time of accreditation. NAMM accredited manufacturers also provide training and CPD on their devices to ensure safety standards are maintained.
NAMM and British Standards
Post 1995 members of the NAMM Technical Committee revised the then long published “NAMM Code of Working Practice”. This comprehensive document provides a practical guide for memorial masons to install all types of memorials fabricated from natural quarried stones from suitable softer limestones to slate and granite. NAMM Technical Committee members served on a committee which led to the publication of BS8415 in 2005 and the revision in 2012.
In addition to manufactured stability devices The NAMM Code of Working Practice provides details of a low cost, safe, pre-poured concrete foundation which is installed at least 14 days before the memorial is installed.
The British Standard 8415 requires memorials to withstand a test force of 70 kg without sudden collapse. This figure was suggested by Professor John Knapton who stated that a 14 stone man would normally exert a force of 30 kg when attempting to stand by pulling himself up using a standing headstone.
Soils such as loose sands and silts
BS8415 states: “For soil types other than medium sands and gravels, clays and rock, e.g. loose sands and silts and loose clays full engineering computations should be submitted for burial authority approval”.
In addition NAMM accredited stability device manufacturers provide technical support and specialised fixings for loose sands.
NAMM also recommends that consideration should be given to the use of continuous raft foundations to overcome possible stability problems. These should be designed in accordance with local building regulations in conjunction with the appropriate British Standard.
Current Developments
The NAMM Technical Committee continues to work alongside British Standards to ensure that future development can take place in future.
Philip Potts
National Executive Officer
Founder Member of the InternationalMonument Federation
Member of the Council of British Funeral Services
VAT Reg: No: 596379180
Registered in England No. 2104686