Firestop garage wall

[fatmcgav]

Hey there

We're mid-extension build currently.
Unfortunately we've had a falling out with the builder over progress and money, so think it's going to be on me to finish up...

On the last building control visit, he advises that the dividing wall between the utility and "garage/storage" room needs to have a 30min fireproof wall all the way upto the underside of the warm roof deck.
We've used posi joists for the roof, and the stud wall lands inline with a posi joist, so I'm trying to figure out how to handle the area above the stud wall.

Can I just run a layer of fireboard plasterboard all the way to the roof deck?

The other complication is that I've got a load of pipes that need to run perpendicular to this dividing wall as we're moving the boiler into the new garage area..
The inspector mentioned an intrumisent color for a 110mm waste pipe. I'm assuming the same would work? Or mastic around the smaller pipes...

Thanks in advance for any advice.

Cheers

 

[Wayners]

Don't think this will help.

I've got a thermalite block wall with fire door in at the end of garage. Its not ideal as the door was causing blocks to move. I had to add timber at top fixing to roof. Wish i could of used concrete blocks.
Garage is double plasterboard. Chicken mesh then insulation with a few floor boards.

At office walls are stud and plasterboard and said to be 30min fire rated. Not sure about that.

Contact building inspector for clarification. They are helpful

 

[^woody^]

Does the wall also need to be thermally compliant with Part L?

 

[fatmcgav]

Does the wall also need to be thermally compliant with Part L?

Yeh, I believe he said it needs to be compliant as the garage is treated as an "uninsulated" area..

 

[thomp1983]

Is the dividing wall a cavity wall?

To meet the fire requirement both the wall and ceiling will need to be either pink fireboard or a dual layer of 12.5mm plasterboard either option will then need plastering too.

You'll need to speak to the building inspector re. the pipe openings, at one point intumescent sealant wasn't acceptable so you need to be very clear about what he'll accept before you make the holes.

Your other option with the pipes is to box them in with fireboard and plaster over them.

 

[fatmcgav]

So the intention was to build a stud wall to divide the area.
I could fairly easily board either side of the posi joist with Fireboard to try and build a separation there aswell...

I wasn't planning on boarding the ceiling in the storage room to save on time and costs...
And either way I'm going to have to deal with pipe penetrations, as there's guna be 12 or so pipes that need to be run for heating, hw and cw to new boiler location...

 

[^woody^]

One layer of 15mm pink board does not necessarily make a 30 minute fire break wall. It's to do with the joints, and you may need Rockwool in the frame to add to the fire protection.

Easiest would be two staggered layers of standard board, they could be 9mm or one layer could be plus skim. These would be on the garage side. Then you could insulate the frame for thermal only, and this could mean a thinner frame.

Intumescent collars in domestic builds are extreme. If the garage is no longer capable of taking a car then the fire risk is much lower. But yes if you just want to placate the inspector then fit one. Be aware that the wall or celling needs to be constructed for the collar.

 

[fatmcgav]

Thanks for the suggestions @^woody^ ...

Double layer of board sounds like the simplest option. Just need to work out how to handle the posi joist area above the new divinding wall...

Intrumiscent collars did sound a bit extreme to me, especially given not guna have a car or flammable liquids... And there will be a mains interlinked smoke alarm aswell...

 

[freddiemercurystwin]

The proven way to achieve this is with a tested fire barrier eg Rockwool Fire Barrier EN eg: https://p-cdn.rockwool.com/syssitea...ctors-installation-guide.pdf?f=20240904084957 I'm not aware of a test where a posi joist with boards each side has been tested like this, in realty a layer or two of board each side as already suggested is likely to be accepted by Mr BC.

 

[^woody^]

If you put the fire protection on the garage ceiling, you won't need to compartmentalise the roof void.

 

[freddiemercurystwin]

Sure but he won't achieve that with 1 layer of PB.