Fire resistant party loft wall.

[Mike DC]

I need to install a party wall in a property we are currently selling. I understand it needs to be fire resistant for 1 hour and If constructed from timber then two walls parallel need to be constructed with fire resistant rockwool in between.

 

Blockwork isnt an option.

 

I’m being swayed towards a metal framed fire resistant plasterboard construction and wanted to check if this is acceptable. The intention would be to build a single wall with fire resistance plasterboard either side,  sandwiching insulation of some sort. Any gaps filled with foam.

 

A few questions for starters. Would the metal frame be appropriate for a fire wall? If so is there a prefer type or size? What is the minimum thickness for the fire resistant plasterboard what is the most appropriate insulation to use?

 

Thanks all.

 

Edited Saturday at 16:44 by Mike DC

[nod]

50 mil MF stud 

Two layers of Fire chech boards Will give you the hour If they are insisting on more You can install a shaft wall 

I stud with 22 mil plank fitted between each stud 50 mil void Then cladded with two layers of fire check board 

This will equal a party wall 

[Gus Potter]

5 hours ago, Mike DC said:

I need to install a party wall in a property we are currently selling.

This can be easyish or horrible in terms of builability. Do you or can you get access from the neighbours side? If you have access from both sides then it can be pretty straight forward as @nod says.

 

If you only have access from your side..it can be a challenge to understate!

 

 

[Mike DC]

Thanks Nod, Gus, I can access both sides no problem. Apologies for clarifying some of the materials, I’m not familiar with some of the terms used.

 

I take it 50mm wide is the size of the cavity/width of the metal stud. I assume 400mm centres. Do I need to double up the boards on both sides of the wall if so what thickness boards? 12.5mm. Can I use a single skin of 15mm boards on each side instead? Any recommendations on what to fill the cavity with?

 

Apologies for seeking out more detail, building standards are a waste of space I can’t make sense of the building regs and the buyer is nailing me to the cross with a Level 3 home survey.

 

Thanks again both the fog is starting to clear.🙂

[saveasteading]

It can be a single stud of timber or steel, and doesn't necessarily need insulation, though you should anyway.

 

You will need a proven detail to satisfy the bco and insurers.

 

Go to " knauf systemfinder " and see the range of standard details.

[Gus Potter]

7 hours ago, Mike DC said:

I need to install a party wall in a property we are currently selling

Hi @Mike DC

 

Are you trying to fire protect the party wall in an attic conversion? Can you provide more detail as we are all guessing here. If you want to get a bit of free help then you need to provide more detailed info.

 

 

[Gus Potter]

25 minutes ago, Mike DC said:

Thanks Nod, Gus, I can access both sides no problem.

Posts over lapping. Lucky you can get to both sides!

 

17 minutes ago, saveasteading said:

Go to " knauf systemfinder " and see the range of standard details

Good tip, also go and create an account for youself on the British Gypsum website and use their deisng tools, you can print off the calcs and so on. To make this relevant you'll need to download the White Book, it has good details and laymans terms guidance etc.. Remember you need to fire protect the perimeter joints around the wall edges so have a look at that too as to how you detail that out.

[nod]

9 hours ago, Gus Potter said:

This can be easyish or horrible in terms of builability. Do you or can you get access from the neighbours side? If you have access from both sides then it can be pretty straight forward as @nod says.

 

If you only have access from your side..it can be a challenge to understate!

 

 

Just to add 

The shaft walling is designed for access from one side only (Lift Shafts ) and will give you 90 minutes exceeding what you are being asked for 

[Mike DC]

15 hours ago, Gus Potter said:

Hi @Mike DC

 

Are you trying to fire protect the party wall in an attic conversion? Can you provide more detail as we are all guessing here. If you want to get a bit of free help then you need to provide more detailed info.

 

 

Hi Gus As per the original post, I need to install a party wall which needs to be fire resistant. I’m not sure what more detail you require? There is no wall at all currently with a brick wall ending at ceiling joist height. If you can be more specific about the detail required I’ll gladly provide it if I can.

 

Thanks for the steer to the white book, it is very helpful with a number of options, making things a bit clearer for me. I assume a surveyor or building control would be satisfied if I followed a spec in the book for 60 minute burn time and submitted that for evidence to them?

Edited Sunday at 15:49 by Mike DC

[Mike DC]

15 hours ago, saveasteading said:

It can be a single stud of timber or steel, and doesn't necessarily need insulation, though you should anyway.

 

You will need a proven detail to satisfy the bco and insurers.

 

Go to " knauf systemfinder " and see the range of standard details.

Thanks that’s helpful, I’ll take a look at the knauf website.

[saveasteading]

3 hours ago, Mike DC said:

You will need a proven detail to satisfy the bco and insurers.

For general interest. About 10 years ago the bco said to me for the first time, that a standard detail was essential in all cases.  ie a manufacturer's tested assembly or an approved iteration.

Prior to that I would sometimes submit a composite design, or a 'common sense' design, plus I had a training certificate to back it.

That change was understandable, given the disasters that had occurred, although on the biggest one the test was fiddled. 

 

My proposals had been, for example, we don't need that layer of plasterboard because we have a skin of brick. 

OR this has been proven with meta stud therefore it works at least as well with timber.

 

@Mike DC  therefore choose not only one that works but also that you can achieve practically.  eg can you get the plasterboard to position and still get your screwdriver in.?

The tests are all carried out in the middle of a sample wall, ie no perimeters. That is somewhere that you can use common sense, in covering all trims and filling all gaps. Do NOT use foam unless it is fire rated. Better compress rockwool into any gaps.

 

 

[Mike DC]

2 hours ago, saveasteading said:

For general interest. About 10 years ago the bco said to me for the first time, that a standard detail was essential in all cases.  ie a manufacturer's tested assembly or an approved iteration.

Prior to that I would sometimes submit a composite design, or a 'common sense' design, plus I had a training certificate to back it.

That change was understandable, given the disasters that had occurred, although on the biggest one the test was fiddled. 

 

My proposals had been, for example, we don't need that layer of plasterboard because we have a skin of brick. 

OR this has been proven with meta stud therefore it works at least as well with timber.

 

@Mike DC  therefore choose not only one that works but also that you can achieve practically.  eg can you get the plasterboard to position and still get your screwdriver in.?

The tests are all carried out in the middle of a sample wall, ie no perimeters. That is somewhere that you can use common sense, in covering all trims and filling all gaps. Do NOT use foam unless it is fire rated. Better compress rockwool into any gaps.

 

 

It’s a good point, jobs evolve, issues arise so I’m always prepared to take stock and adapt as required. I try and be as informed as possible at the beginning and start with a clear end in mind. It avoids that slip into bodging territory if challenges are present.

[ETC]

Just give your local British Gypsum rep a call. He/she will be more than delighted to design and specify the wall. And yes - no foam - fire stop with an appropriate material.

Edited Sunday at 21:30 by ETC