My building inspector tells me that I must paint the stud walls and ceilings with a fire retardant paint to comply with building regulations.

Has anyone got a recommendation for paint that will do the job and be compliant?

Thanks in advance

Is the garage integrated with house? Or is it a separate building?

27 minutes ago, Arrenite said:

I must paint the stud walls and ceilings with a fire retardant paint

not necessarily. we need to know more. location re house and boundary. construction, why ply?

46 minutes ago, BotusBuild said:

Is the garage integrated with house? Or is it a separate building?

It’s not connected to the house

32 minutes ago, saveasteading said:

not necessarily. we need to know more. location re house and boundary. construction, why ply?

The garage is concrete block, reinforced concrete slab

And the floor area? Over 40m2? Usually under 40m2 walls and ceilings need a spread of flame classification of D-s3,d2 which your plywood could well achieve. However, like in many cases you can't actually prove it. If there are manufacturers details on the boards you may be able to ask them before you spend your cash

is the garage on or near a boundary?

I will assume you have already committed to plywood.

Does the BCO say what the purpose / danger is? They are right that vertical timber can burn vey fiercely once ignited, as the flame races up the preheated wall.

But in an isolated and unoccupied building there is miniscule risk to persons.

So you can get advice ( phone Envirograf, where a real person will advise, and they will have test results) on whether they can supply a surface retarder that will satisfy the requirement.

If it needs long term protection then it gets expensive. Lots of layers then a sealer.

If you are near a boundary then you are required to stop any fire affecting the neighbours (who might build close). A clock wall does this so the internal surface should not matter.

The alternative is to put plasterboard over the ply. not ideal for a robust space esp if you want to hang tools.

Other paint suppliers are available, and merchants will sell you the stuff without any query, some with a diy certificate.

But I've only used the one (Envirograf) for decades, and they are expert and not one of the big companies.

The OP needs to get clarification as the purpose of the request. There is often confusion between the requirement to limit the spread of fire across boundaries between buildings and limiting the spread of fire across surfaces within buildings.

In the former the construction of the external wall, it's proximity to the common boundary and the amount of openings are the key features. These are set out in Requirement B4 of Part B of the Regs.

The latter is more about restricting how quickly flame can spread across an internal surface and whether it will contribute to extending the fire by perhaps dripping burning droplets or particles. Requirement B2 controls this.

I suspect from the very limited information given, that BC are concerned about the amount of plywood exposed on the walls and ceilings may not comply with the limits set by Table 4.1 on page 43 of the Approved Document.

Whenever you get a request to do something by a BCO that you do not understand it is sensible to ask for an explanation and (politely) request the basis of the request so you can at least see if there are any exemptions or minor changes that can be made that have not been made clear to you.