Intumescent strips for cladded areas

[Lincolnshire Ian]

Hi folks

We need intumescent strips to close the 50mm void in our timber frame where we use cladding (about 30% of the house). 

I am more than a little shocked by the difference in price between cavity socks for the masonry walls and intumescent strips for the cladded walls. Does anyone have a supplier that offers intumescent strips at a reasonable price? 

Thanks 

[nwnw]

I was reading posts on this recently and it seems that Envirograf is generally cheaper than Tenmat. 

However, I did see that folks were getting away without using intumescent strips if they had an open 'rain screen' cladding format, which is what I'm looking at.  Will need a chat with BCO.

[Mr Punter]

43 minutes ago, nwnw said:

I was reading posts on this recently and it seems that Envirograf is generally cheaper than Tenmat. 

However, I did see that folks were getting away without using intumescent strips if they had an open 'rain screen' cladding format, which is what I'm looking at.  Will need a chat with BCO.

 

Yes I think the chimney effect is much reduced if there are gaps between the boards.

[Kelvin]

I might have some I could sell you at a fair price. Let me know exactly what you need and I’ll have a look at what I have. 

[saveasteading]

4 hours ago, nwnw said:

Will need a chat with BCO.

Firstly Envirograf. My favourite in this field as they understand fire and the products, many of which they first produced. I haven't contacted them for years but always found their advice interested, realistic  and worthwhile.

 

The BCO unfortunately probably will want to see a test certificate for exactly the situation.

The purpose of the strip is to stop the spread of flame, and a lump of wood or metal would do it fine.  But nobody has tested that as there is no market. A product exists so you probably have to use it. 

If the manufacturer made the exact same product but wrapped in red , and tested with timber, or wrapped in blue and tested in metal cladding, then those would be the test certificate that existed, and you have to use the red or  the blue.

 

How about intumescent paint on a timber block or metal profile?  A pragmatic and knowledgeable BCO might agree to it: after all it has the magic word intumescent.

 

I'm not guessing btw. I've worked on this a lot, including a high level course, but there were no qualifications awarded.

3 hours ago, Mr Punter said:

the chimney effect is much reduced if there are gaps between the boards.

Yes, but the effect of heat rising is still there. A fire spreads very rapidly upwards, chimney effect or not, as the material above is preheated, and then a flash flame can occur.

 

[Lincolnshire Ian]

8 hours ago, Mr Punter said:

 

Yes I think the chimney effect is much reduced if there are gaps between the boards.

Our architect gave us the option of having vents added to the cladding or intumescent strips. We thought the vents looked pretty poor, but there might be more elegant solutions. 

[Lincolnshire Ian]

6 hours ago, Kelvin said:

I might have some I could sell you at a fair price. Let me know exactly what you need and I’ll have a look at what I have. 

Ohh, that's a good idea. 

I need 32m to expand to fill a 50mm cavity. 

Thanks 

[saveasteading]

35 minutes ago, Lincolnshire Ian said:

Our architect gave us the option of having vents added to the cladding or intumescent strips

I hadn't seen this vent theory as being accepted practice. Do you have any backup to it as I'd love to know more?

 

The main thing is never to build a bonfire against a timber-clad house.

 

[Kelvin]

56 minutes ago, Lincolnshire Ian said:

Ohh, that's a good idea. 

I need 32m to expand to fill a 50mm cavity. 

Thanks 

I’ll message you separately when I get home tomorrow and let you know exactly what I have. 

[Gus Potter]

10 hours ago, nwnw said:

However, I did see that folks were getting away without using intumescent strips if they had an open 'rain screen' cladding format, which is what I'm looking at. 

And here is the crunch. I made what was a admittedly a rambling post a few days ago about principle designers in response to a thread by @Oceanjules.

 

One point here is that it's not what you can get away with.. much more about designing safely and the onus is now much more on the designer and everyone involved in that process, the liability has now much been past to the designer. 

 

There are two key principles.

 

1/ If a fire starts the occupants need to have time to exit safely.

 

2/ That the fire fighters should not be put at risk. 

 

But here is the business case. The onus is very much more on the designer. One thing my PI insurer broker pointed out to me when we were talking the extent of my fire design liability is, hey Gus.. from the underwriters perspective.. a fire does not need to occur, all it needs is for a Client to potentially later say.. your design could be flawed and it's up to you to prove it's not! This liability does not lie with BC anymore but with the designer, although to support our case we may refer to BC regs and manufacture's data. But as soon as we go off piste life becomes a design and cost adventure!

 

 

 

 

 

 

 

 

 

 

[Dunc]

Just installing ours right now. Envirograf CV strip significantly less expensive than the Tenmat offering. Got ours from www.lifelinefireprevention.com

Probably worth checking with BCO exactly what they would want to see; the regs are pretty general and your individual building may not need "everything".

[Kelvin]

22 hours ago, Kelvin said:

I’ll message you separately when I get home tomorrow and let you know exactly what I have. 

@Lincolnshire Ian I’m still away. Back tonight so will let you know tomorrow. 

Edited Tuesday at 18:00 by Kelvin

[marmic]

[marmic]

 

 

Jit Sehra Senior Technical Fire Consultant Intumescent Systems Ltd T/A Envirograf p: m: 01304 842 555 07831451628 e: Jit.Sehra@envirograf.com a: Intumescent Systems Ltd, Envirograf House, Barfrestone, Dover, Kent, CT15 7JG, United Kingdom w: www.envirograf.com

[marmic]

Jit was extremely helpful........... cost lower than other products i found.  significanty in some cases