Intumescent fire cavity barriers

[Blob the Builder]

My timber cladding is arriving this week, with thousands of nails. But first prep still to do including holding down straps to my timber stud panels, rodent mesh to the bottom of the cavity, and fixing of intumescent fire cavity barriers. As my wall construction is timber stud panels with OSB sheathing and membrane, 50 mm cavity, then horizontal timber cladding on vertical 50 x 50mm battens, i am needing to maintain ventilation of the cavity for the back of the cladding from dpc to eaves. But i need to install ventilated cavity fire barrier horizontally at mid floor to compartmentalise, and possibly elsewhere.

Does anyone have experience in which barrier to use?

I'm supposing intumescent as it allows ventilation of the cavity, but the strips are really expensive, £20+/m

 

[Mr Punter]

I have used these in a sloped roof covering 2 dwellings and yes, they are expensive. I got mine from Envirograf. They may be able to give advice on what product.

 

I am not sure they would be all that effective with timber cladding, as they need to get fairly hot to expand, by which time the fire may have gone beyond the fire stops. Again Envirograf should be able to let you know.

[Blob the Builder]

On 04/02/2019 at 09:38, Mr Punter said:

I have used these in a sloped roof covering 2 dwellings and yes, they are expensive. I got mine from Envirograf. They may be able to give advice on what product.

 

I am not sure they would be all that effective with timber cladding, as they need to get fairly hot to expand, by which time the fire may have gone beyond the fire stops. Again Envirograf should be able to let you know.

I'll check them out; ive been looking into Tenmat who do one specifically for timber cladding......

[Cambs]

On 05/02/2019 at 21:37, Blob the Builder said:

I'll check them out; ive been looking into Tenmat who do one specifically for timber cladding......

 

Resurrecting this thread - how did you get on with this?  I have a similar requirement - timber frame, 50mm vertical battens and timber cladding

[jamieled]

Has anyone else got examples of ventilated firestop detail for a timber clad house? Either proprietary intumescent barrier or something else? Could use some inspiration.

[Visti]

Envirograph stock a good range for this purpose. Our neighbour went with their CV strips mounting them on battens to cover the distance of the full cavity. They come in various thicknesses, but would have cost us £13.18/m2.

 

We went with the RSM/I range which are able to cover a deeper cavity than those above at less price.

We paid £10.38/m2 for 100mm deep ones, with the intumescent able to cover the final 40mm in case of a fire (138mm cavity on ours)

Attached documentation on this range FYI.

 

Tenmat also do similar products but we found they were about double the cost of the envirograph. 

 

Cavity detail of ours was:

IS-55-RSM-WEB.pdf 2017-Efectis-R001685[Rev.2]_Intumescent_Systems_snp.pdf

[jamieled]

Cheers @Visti, very useful!

[eandg]

On 03/02/2019 at 21:08, Blob the Builder said:

My timber cladding is arriving this week, with thousands of nails. But first prep still to do including holding down straps to my timber stud panels, rodent mesh to the bottom of the cavity, and fixing of intumescent fire cavity barriers. As my wall construction is timber stud panels with OSB sheathing and membrane, 50 mm cavity, then horizontal timber cladding on vertical 50 x 50mm battens, i am needing to maintain ventilation of the cavity for the back of the cladding from dpc to eaves. But i need to install ventilated cavity fire barrier horizontally at mid floor to compartmentalise, and possibly elsewhere.

Does anyone have experience in which barrier to use?

I'm supposing intumescent as it allows ventilation of the cavity, but the strips are really expensive, £20+/m

 

How did you work your cavity barriers with your battens for the cladding?