I'm a handyman and my clients have asked me to replace their old gas meter cabinet located at the rear of the building (external). The cabinet covers 6 gas meters (203cm high x 108cm wide x 15cm deep) and is made of chipboard that gradually decayed over the years (see photos)

Instead of chipboard, I am planning to use 2" x 5" C24 treated, sawn, structural timber for sides & top. Instead of the heavy, large door (180cm high x 101cm wide) with butt hinges, I am planning to install a double door made of sealed 18mm hardwood core plywood, fitted with flush fit hinges so the doors won't be concealed but will cover the entire frame. The chipboard plinth (33cm high and 101cm wide) will be replaced by plywood as well.   

I had a look at The Gas Safety (Installation and Use) Regulations 1998, in particular UK Statutory Instruments, 1998 No. 2451, PART C - Regulations (https://www.legislation.gov.uk/uksi/1998/2451/regulation/13) and also stumbled across a document published by Cadent  (https://cadentgas.com/getmedia/3d5f8cb1-0c82-453d-bdf9-a10f977a0a35/LP-Services-and-Meter-Boxes-Guidance-v2.pdf),  i.e. 

>>Purpose-built meter housing. If you have decided to have purpose-built meter housing (which will need to be installed by your builder/developer) the following design criteria shall be met: [...]     • They are resistant to the surface spread of flame in accordance with BS 476-7:1997, Class 2; • Consumer access is gained only by a special key [...]>>

Here my questions:

1. To achieve fire resistance in accordance with BS 476-7:1997, Class 2, I would opt for two coats of clear top coat. Prices seem to vary between £40 per litre and £180 per litre. Does anyone have a recommendation as to which product, reasonably priced, meets my requirements (clear & top coat), BS 476-7:1997, Class 2 standard, and comes with the required certificate, assuming that any fire resistant paint supplied without certificate is of no value if there is an inspection?                                                                                                                 

2. I was planning to seal the gap between cabinet and house walls with universal silicone sealant. Do I have to use fire resistant sealant instead? If so, any recommendations?

3. I was planning to secure the cabinet against the house wall with 4 angled steel brackets & wall plugs. Is that allowed or does the unit have to be free standing?

4. My client instructed me to not add a lock to the cabinet. Cadent mentioned that a lock with special keys that have to be issued to all residents, shall be installed. I consider "Shall"-conditions as not legally binding. Would you agree that compliance is achieved if the cupboard doors are kept closed with ball catches but without a lock.                                                                                                                          

In the UK, the word "shall" is used in legal documents to indicate a requirement that is binding and must be implemented. It is a modal verb, which is a verb used to express an obligation. So I'd put a standard triangle key meter cupboard lock on or a T-bar lock and distribute keys.

 

For the protective coatings and test data I'd suggest visiting https://envirograf.com/ & https://thermoguard.uk/