Technical Handbook / Environment / combustion appliances / 3.17 - 3.22 Versus Part J

Google "Building regulations, Combustion appliances" and the page will fill up with references to "Part J". Be aware, you are NOT seeing Scottish building regulations.

You need to go via Scot.gov to access the Scottish "Technical handbook / Domestic" to find the Scottish equivalent. (Its a fairly long winded menu affair to get there rather than the English, catchy "Part J")

However, with a bit of effort you can start to make comparisons. I am going to draw attention to one difference herein, (But its NOT the only one!) Minimum flue diameter.

(Quick qualification here, and a wee factoid that many are not aware of. Building regs, north and south of the border are NOT set in stone. In one important respect they can be altered. IF A PRODUCT MANUFACTURER TELLS YOU TOO. Both nations recognise that confining manufacturers to build regs could stifle product development so manufacturers have some license in install instructions to defer from build regs)

FLUE DIAMETER

Scotland

England

So, in shorthand, (Assuming a manufacturer hasn't said otherwise) "Eco" appliances in England can legitimately be installed on a flue diameter of 125mm (5") In Scotland given the same qualification, the minimum requirement is 150mm (6")

Is it a difference that makes a difference?

Consider this. The difference in surface area between a 5" or 6" flue is 20% so a 5" flue will inevitably soot up faster. Gather a half inch of soot on a 6" flue and you will reduce the diameter to a still useable 5". Do the same in a 5" flue (And it will occur faster) and the flue is reduced to an unusable 4".

I see so many liner installers habitually fitting 5", its marginally cheaper, and easier to install, but it may be contravening Scottish regs, this could be vital in the event of a fire and insurance claim.

Still, keeps me in a job!

 (Another difference between north and south in another area of construction was noted as being important enough to cause debate in parliament.

Post Grenfell, consider these statements from the respective building regs with regard to external cladding on buildings

Scotland

Mandatory Standard

Standard 2.7

Every building must be designed and constructed in such a way, having regard to the height, use and position of the building, that in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building is inhibited

England

Requirement

 External fire spread B4. (1) 

The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another having regard to the height, use and position of the building

Do "Resist" and "Inhibit" mean the same thing? Discuss.)