Firestop! where does it go in a timber framed house?

[Triassic]

I’m at the cladding stage on my timber frame construction. Following the Grenfell disaster I changed from larch to fibre cement Cedral cladding and part renderboard and render. The TF company supplied lengths of fire stop, insulation in a red plastic sausage.  Where does it go within the wall build up?

Edited June 14, 2019 by Triassic

[nod]

  On 14/06/2019 at 08:37, Triassic said:

I’m at the cladding stage on my timber frame construction. Following the Grenfell disaster I changed from larch to fibre cement Cedral cladding and part renderboard and render. The TF company supplied lengths of fire stop, insulation in a red plastic sausage.  Where does it go within the wall build up?

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Around the top of the roofline Pushed into the cavity 

There to stop fire entering the roof via the cavity 

Normally puncture each one as you put them in 

[dpmiller]

it's a cavity closer, so corners, eaves, and horizontally at FF level IIRC. Check with your BCO.

[nod]

  On 14/06/2019 at 08:47, dpmiller said:

it's a cavity closer, so corners, eaves, and horizontally at FF level IIRC. Check with your BCO.

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  On 14/06/2019 at 08:47, nod said:

Around the top of the roofline Pushed into the cavity 

There to stop fire entering the roof via the cavity 

Normally puncture each one as you put them in 

Expand  

 

[nod]

[Triassic]

What about Timber Frame and exterior cladding?

[Declan52]

At the corners from bottom to the top so from ground floor to the roof. If it's a 2 storey then along where the joists are right round the building. What your trying to do is stop any fire from spreading. So it can't get up the cavity and into the roof or can't get from one side of the building to the other via the cavity.

[Mr Punter]

  On 14/06/2019 at 08:47, dpmiller said:

it's a cavity closer, so corners, eaves, and horizontally at FF level IIRC. Check with your BCO.

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Trouble is, if he closes the cavity the ventilated rainscreen cladding will not work as designed and he may get damp issues.

 

The cladding manufacturer will show continuous ventilation top and bottom.

[Carrerahill]

From building guide:

 

"Firestops to be installed in cavity around all apertures, at wall head, corners and at centres not exceeding 10m in runs of wall"

 

 

[bissoejosh]

Aren't these only needed with an external blockwork skin? As mentioned you don't want to close the timber frame cavity else the ventilation is gone.

 

 

Edited June 14, 2019 by bissoejosh
clarity

[Mr Punter]

You should close the cavity (usually with 2 x 2) around windows and doors.  This stops a fire in the house breaking through into the cavity.

 

You could fix intumescent barriers at the top which would choke down the chimney effect in the event of a fire.  They don't seem particularly easy to find or specify though.

[oldkettle]

I was searching for standard TF details and found quite a few documents available online. For example, https://www.taylor-lane.co.uk/wp-content/uploads/2018/03/TL-Standard-Wall-Details-v4.5.pdf

 

[Mr Punter]

  On 14/06/2019 at 13:02, oldkettle said:

I was searching for standard TF details and found quite a few documents available online. For example, https://www.taylor-lane.co.uk/wp-content/uploads/2018/03/TL-Standard-Wall-Details-v4.5.pdf

 

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But this does not have what @Triassic needs which is spec and detailing for fire barriers in ventilated rainscreen cladding

[dpmiller]

... which is why checking with the BCO is best value.

[Triassic]

  On 14/06/2019 at 16:27, dpmiller said:

... which is why checking with the BCO is best value.

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I’ve installed fire-stops vertically around the building at the intersections of internal walls, so the kitchen is isolated from the dining room, which is isolated from the stairs etc. I’ve also installed fire stops around each of the windows.

 

The BCO is visiting on Monday, I’ll ask him then what he thinks of my efforts so far.

Edited June 15, 2019 by Triassic

[trialuser]

What did he think and what did you use, the intumescent stuff seems specialised andvery expensive.

I will need to firestop and have a ventillated cavity, are there other options?

Thanks

[SuperJohnG]

+1 on this. I have renderboard and also open rainscreen cladding on a SIPS build 

[Onoff]

  On 14/06/2019 at 08:47, nod said:

Around the top of the roofline Pushed into the cavity 

There to stop fire entering the roof via the cavity 

Normally puncture each one as you put them in 

Expand  

 

You say "puncture" as in make a hole in I assume. Isn't that defeating the object? Can't the fire get up through the hole?

[nod]

Just the way it’s done 

Just a stab to let the air out 

[Declan52]

When your nailing it to the outer frame it gets punctured plenty of times. Without doing it you would never get it down the cavity.

[nod]

  On 08/10/2020 at 05:21, Declan52 said:

When your nailing it to the outer frame it gets punctured plenty of times. Without doing it you would never get it down the cavity.

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Exactly 

The plastic is just a cover to keep the sock together 

Throw one on a fire and see how long the plastic lasts 

[Ian]

  On 07/10/2020 at 22:27, trialuser said:

What did he think and what did you use, the intumescent stuff seems specialised andvery expensive.

I will need to firestop and have a ventillated cavity, are there other options?

Thanks

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Yes, you can use a timber batten

[trialuser]

Thanks, but won't that then block the cavity, particularly atthe junction of ground and first floor. and the eaves.

Another problem is cladding on the ff will be wriggly tin, so not easy to block with timber.

I think I understand the method with a masony skin, but I cant see how you can have a ventillated cavity and have it firestopped when cladding with wood or similar

[Carrerahill]

  On 14/06/2019 at 08:37, Triassic said:

I’m at the cladding stage on my timber frame construction. Following the Grenfell disaster I changed from larch to fibre cement Cedral cladding and part renderboard and render. The TF company supplied lengths of fire stop, insulation in a red plastic sausage.  Where does it go within the wall build up?

Expand  

Top of the cavity, corners, around windows and doors, and every 10m vertically in a wall (or whatever your LABC want to see or drawings etc.)  

 

As for ventilation your vent layout should take into account the compartmentalisation of the cavity with the firestops and be laid out in such a way to ensure it is still ventilated. I added lots of weepers to my outer wall, your cladding so a bit different but you will find a way.

 

 

Edited October 8, 2020 by Carrerahill

[NewToAllOfThis]

We are building timber frame with wood cladding, the BCO has asked for all firestops to be shown on the drawings, is this normal or would they just come out and inspect the work once done ?

Edited October 16, 2020 by NewToAllOfThis