Intumescent paints on Lath & Plaster

[Dannyboyski]

So my building controller says Lath and plaster ceilings do not meet the 30 min fire protection, so as part of our loft conversion we are required to insert rockwool Flexi within a galvanised steel mesh between the joists in the floor above.

My LBC says since grenfell they no longer accept intumescent paints on the L & P. I retouched this topic with him recently and he seemed to get a bit angry and suggests we've covered this and they're no longer accepted. I'm just not quite sure why?

The intumescent paint is costly but I suspect still cheaper than the labour cost of pulling up all the skirting boards and original floorboards.

Is this something others have encountered in different regions? I'm in east Devon.

I'm reluctant to pull the lot down and replace with gypsum. seems so wasteful.

 

[freddiemercurystwin]

Since Grenfell, with regards to fire protection, LBC typically won't accept anything that's not been tested specifically for its proposed use. Yesteryear before Grenfell LBC would have just rolled with it like everyone else because historically 'it's always been done like that' and an 'it'll be fine' attitude but that's all gone out the window now.

So to use your paint you'd need to find an intumescent paint manufacturers test for such a situation and that product would need to meet Building Regulations Approved Document 7 - Materials and workmanship. Alternatively you could potentially employ a fire engineer to provide a backup or justification for your proposals (if they can) but that's gonna cost hundreds of pounds at least so likely to be prohibitively expensive.

I don't know your setup but generally in loft conversions there are no boards so some rockwool is a sensible solution.

 

[Dannyboyski]

Thanks for your reply Freddie, the loft (2nd floor) is easy because it’s not boarded. So I can just Chuck rock wool in it from above.

It’s the first floor that causes massive disruption, and I’m trying to avoid lifting all the floors.

Dan

 

[frutbunn]

I've never heard of intumescent paints being used on a Lath and plaster ceiling to increase fire resistance and I've dealt with thousands. If its independently tested then BC have to accept it. I'll have a look at the details at may update this reply once I've had time to digest the information.
The requirement is for 30 minute fire resistance, this hasn't changed since Grenfell. The method used is entirely your choice as long as it has been tested. The method you are proposing is OK, however it can be difficult to install correctly if there is pipework, services etc in the way, the Flexi must be laid tight to the ceiling and existing joists and cover the entire ceiling area. I've condemned quite a lot of half arsed installations of this where the mesh/insulation was laid just over the top of the joists or only under the new floored area only or have just used (cheaper) loft fibreglass!

 

[Nakajo]

If the floor boards are 'original' what exactly is being 'converted'

 

[frutbunn]

If the floor boards are 'original' what exactly is being 'converted'

Its the first floor, the loft conversion is a material alteration under Part B so the means of escape to the loft has to comply with means of escape as well as upgrading the fire resistance of the elements of structure. Although to be fair I've never (or heard of anyone else) required it at first floor apart from on first floor flats, but strictly speaking the LA are correct.

 

[freddiemercurystwin]

Well this one says it's been tested on a L&P ceiling but you'd need to check it out properly and your BCO might look for the Part 7 too so you might have to do some detective work.
https://envirograf.com/product/fire-resistant-coating-for-lath-and-plaster-ceilings/

 

[Dannyboyski]

Thank you for the replies everybody.

Yes we need a protected stairwell, but LBC have also insisted we upgrade the fire resistance on the first floor. Our new 2nd floor (loft) is easy as there are no floorboards laid. So I will install the rock wool flexi (1 hr protection apparently) between the joists (tight with the L&P below)

This is the article I read regarding potential coatings on L & P here:


https://www.buildingconservation.com/articles/fireresist/fire_resistance.htm

 

[Dannyboyski]

Well this one says it's been tested on a L&P ceiling but you'd need to check it out properly and your BCO might look for the Part 7 too so you might have to do some detective work.
https://envirograf.com/product/fire-resistant-coating-for-lath-and-plaster-ceilings/

yes this is the company I had seen. Maybe I will compile an email and send it across to the LBC.

appreciate everyone’s responses.

many thanks

Dan

 

[Dannyboyski]

I should add I feel the L & P would hold up quite well in a fire. It is 1” thick plaster and in excellent condition for the age. We are taking another wall down elsewhere and I’m tempted for my own curiosity more than anything to hit it with my blow torch first to see how it behaves.

I wonder whether a fire engineer might be able to pass it without modification if it is substantial enough.

My LBC has made reference to fire engineers before. And I’ve tried to get in contact with several on numerous occasions. It appears there are only a handful in the uk and they are fairly elusive beasts.

 

[freddiemercurystwin]

I really can't imagine going the fire engineer route is financially viable.

 

[frutbunn]

I've had a chance to have a look and it appears to be tested, though it doesn't give any other information as to who carried it out but the site does list a whole range of independent bodies. There may be conditions laid out regarding an assessment of the ceiling as to its condition and suitability for the treatment, hence B Controls possible(?) reluctance to accept it, its certainly an issue I would raise if only to confirm its accreditation. This may be why they mentioned a fire engineer as a way of absolving any responsibility as to the ceilings suitability.

 

[^woody^]

Surely the requirement, albeit tenuous, would only apply to the floor of the protected escape route? And you should take this up with the BCO's manager or his manager as the existing ceiling and floor should be a suitable arrangement.

An upgraded alarm for early detection or a suppression system would be suitable alternatives.

 

[frutbunn]

Surely the requirement, albeit tenuous, would only apply to the floor of the protected escape route? And you should take this up with the BCO's manager or his manager as the existing ceiling and floor should be a suitable arrangement.

As well as the means of escape issues, there's an argument that could be made that by increasing the number of floors all elements of structure would need to have the required fire resistance.

 

[Dannyboyski]

My understanding is that this is in addition to the early Detection fire alarm system.

I am deliberately trying to avoid a sprinkler system as IMO this is overkill for a domestic residence. And the costs are absurd. Particularly as our water pressure isn’t high enough to run it so would require another very large tank in the roof.