Fire rating calculation

[henkeson]

I need some help calculating the fire rating that the following external wall construction meets.

From the outside:
22mm wooden panel
28mm air gap (wood battens)
Wind barrier
145mm stud frame with mineral wool insulation
12mm OSB

 

[fgo]

No plaster?

 

[witten]

Which requirement do you need to meet?

 

[henkeson]

Would prefer to avoid plaster since it's a storage. Needs to fulfill EI30 due to proximity to the neighbor's garage.

 

[Rickard.]

It is more than enough for ei30. Then one might wonder how moisture-resistant the construction is, but that's another matter.

 

[henkeson]

Need something more concrete that shows it meets EI30. A calculation using the addition method or similar.

 

[Rickard.]

Need something more concrete that shows it meets EI30. A calculation with the addition method or similar.

It shouldn't be necessary. A wall of 45x95 insulated with stone wool and with 12mm plywood or OSB on both sides meets EI30, so anything above or equivalent to that is approved. Yours is so far beyond that it seems irrelevant to justify why it should be approved.

 

[henkeson]

Feels good to have something to lean on when ticking the box on the control plan.
Haven't found any examples with a board on just one side of the stud frame, but maybe the facade compensates for that.

 

[henkeson]

It is more than enough for ei30. Then one might wonder how moisture-proof the construction is, but that's another matter.

Why wouldn't it be moisture-proof?

 

[Rickard.]

I haven't found any examples with panels on only one side of the wall frame, but the facade might compensate for that.

It does, I can't find a super good source (in 1 minute of searching) but melbygarage writes this: "For example, we construct our insulated garages with: 12 mm chipboard, at least 95 mm glass wool insulation, and 22 mm exterior wooden cladding. This construction meets fire rating EI30."

With that much insulation, I assume you plan to keep it heated year-round, and then some form of vapor barrier/vapor brake is recommended. You might have planned for that but didn't mention it since it wasn't relevant to the topic

 

[henkeson]

The starting point is to skip the plastic. As mentioned, it is a storage space and the addition of moisture to the air is practically non-existent. Will keep it frost-free but nothing more.

 

[Mikael_L]

My link doesn't work anymore, don't click on it, it seems to lead to something suspicious, maybe. I will report to the moderator that they can feel free to scrap the link there.

I'm including a PDF from Paroc instead, where the addition method can be found on the last pages:

 

[Mikael_L]

I can insert what was sensible from the deleted post here:

Here you have the addition method
page 24

It is easy to apply and calculate with.
Feel free to download the document to your own computer.
Pages 24-25 can also be printed out and included as an appendix to the calculation.