Fire rating with chipboard + plasterboard?

[Mrlewies]

Hi. I am building new and will have a garage in the same building as the main house. The garage is located under the living area. I have heard from several sources that to achieve 30-minute fire protection on the exterior walls, you can use a regular 13mm drywall + a regular 13 mm chipboard/OSB board. But my inspector is not sure about this!

So, what applies? Is it okay with 1 drywall + 1 chipboard = 30-minute fire rating?

If so, what about the ceiling? Do I have to achieve 60 minutes there? If so, 2 drywalls + 1 chipboard? Is it worth the extra work, etc., with 3 boards in the ceiling? It's always nice to have chipboard behind to attach things to, I think. But it's annoying with all the electrical boxes, etc.!

But the most important thing is if it works with the boards? Anyone who is an expert on this and knows for sure?

 

[thomas33]

This provides some tips on different boards and studs to achieve fire rating.
http://www.traguiden.se/tgtemplates/popup1spalt.aspx?id=1406

 

[Mikael_L]

In this brochure, you will find both typical constructions as well as a good description of the addition method and values for different materials to use together with the method.
It is quite easy to calculate by yourself.
Sketch out the wall you envision and then calculate exactly according to the instructions, with the correct (specified) coefficient for the different parts.
http://www.stenull.paroc.se/produktdat/pdf_down/Brand_ljud.pdf

 

[ronolo]

We use Gyproc's classifications in many cases when designing walls. Their handbook is free to order and is also available online. Here is a shortcut to a convenient compilation if the wall is built with metal stud/frame. http://www.gyproc.se/files/Gyproc/Library/Handbook/SE/HB8-2.1.6.pdf

It also describes which classification is required in many common wall types here: http://www.gyproc.se/files/Gyproc/Library/Handbook/SE/HB8-2.1.0.pdf

There is nothing mentioned about fiberboards among their classifications, but in an example like an EI60 wall with 2*13mm gypsum/side, it is okay to replace the innermost board in both layers with, for example, a 12mm OSB board. It's slightly worse, but still meets EI60.

 

[Mrlewies]

thanks for all the nice answers. That almost has to mean that it's okay then?

 

[Mikael_L]

thank you for all the nice answers. It almost has to mean that it's okay then?

Yes, but only almost then ...

I didn't read an answer here saying that what you assume is correct.

I gave you a good starting point on how you can calculate and check that yourself with very little effort and at the same time learn a bit more.
And besides, it might be pretty good for you to know it yourself later when you talk to your KA.

Showing your own calculations and/or sources is 1000 times more impressive when you talk to the KA than just saying that you read on "a forum" that it is OK.

 

[slacker]

I haven't checked the links above but the requirement still exists for FireSeal, or an equivalent product, after each layer!?

 

[mycke_nu]

In that case, what about the ceiling? Do I need to achieve 60 minutes there? If so, 2 gypsum + 1 chipboard? Is it worth the extra work with 3 boards on the ceiling? Always nice to have chipboard behind to attach to, I think. But troublesome with all the electrical boxes, etc.!

Since there are both intermediate beams and spacing panels above the gypsum, there's usually a decent amount to attach to, but you obviously have to find the right spot before screwing up something heavy.

Electrical boxes I don't think are too bad, just measure carefully.

 

[ronolo]

I haven't checked the links above but the requirement for FireSeal, or equivalent product, still exists after each layer!?

I have no additional source, but the fire engineer we use says that fire sealant is required on each side of the wall. This should be placed closest to the fire and thus applied after the last layer of boards is mounted.