Plywood w/one hour fire rating - Contractor Talk - Professional Construction and Remodeling Forum

fireguy · 09-10-2008, 04:01 AM

A client is building a concession trailer. He builds about 50 - 75 specialty trailers per year, but has never done a commercial kitchen before. The theory is any concession trailer is to be built to Oregon Mechanical Specialty Code. Code requires a 1 hour fire rated wall between the Type I exhaust hood and combusables. Of course, I told him all he needs to do is screw a single layer of 5/8 sheet rock down and hang the hoods. He told me the sheet rock would not last 10 miles on the hiway before it broke all to pieces. He then asked if I knew of 1 hour rated plywood. I am not aware of any 1 hour plywood. Is there such an item as 1 hour plywood? And if so, who makes it?

Jason W · 09-10-2008, 08:38 AM

Google is your friend.......

http://www.google.com/search?sourcei...+rated+plywood

Meetre · 09-10-2008, 09:12 AM

why not use some frp?

fireguy · 09-12-2008, 03:17 PM

Quote:

Originally Posted by Meetre

why not use some frp?

Customer;s customer wants S/S backsplash. My experience w/frp is that it does not clean as well as S/S. I have also seen it blackended by the heat and grease.

I printed & faxed some stuff to the customer.

Thank you for the help.

neolitic · 09-12-2008, 04:21 PM

Interested in why they would think
that after a one hour fire anyone
would care that there was one wall
left on that trailer.

Ivinni · 09-12-2008, 05:07 PM

Quote:

Originally Posted by fireguy

A client is building a concession trailer. He builds about 50 - 75 specialty trailers per year, but has never done a commercial kitchen before. The theory is any concession trailer is to be built to Oregon Mechanical Specialty Code. Code requires a 1 hour fire rated wall between the Type I exhaust hood and combusables. Of course, I told him all he needs to do is screw a single layer of 5/8 sheet rock down and hang the hoods. He told me the sheet rock would not last 10 miles on the hiway before it broke all to pieces. He then asked if I knew of 1 hour rated plywood. I am not aware of any 1 hour plywood. Is there such an item as 1 hour plywood? And if so, who makes it?

A 1 hour wall is only a 1 hour wall if it has both sides of the wall, which, in the case of a vent hood, would mean you have to have a shaft wall and you probably don't have room or money for that.

I insulate vent hood exhaust systems in restaurants that are wood frame contruction and the latest in technology is the fireblanket from 3M Firestopping. The installation instructions seem to be very intricate but after you read them for the 5th time, things become more clear.

Google "3m firestop distributor+your closest big city name" and you should be able to find a fast, cost efficient solution.

If you need specifics, shoot me a pm or email at rrowe@firestop-llc.com

Good luck.

fireguy · 09-13-2008, 04:36 AM

I usually use the 3M 15A on ducts. It is expensive, but faster and much less expensive than framing a chase and putting in a layer of 5/8 sheet rock and getting it mudded. In Oregon, we are allowed to use a single layer of 5/8 for a 1 hour rating. For complete hood installs, I use a local sheet metal shop. They use another brand, 2 " and only a single layer. It is less expensive than 3M. Some day I will write down the name, and change over from 3M.

I have already told my customer that I strongly recommend he use the 3M insulation for the ducts. This kitchen part of the job was speced and started by another company. they installed low proximity eyebrow hoods. they should have used canopy hoods. There will problems with the clearances, head room and clearance to combustable. The duct is at the edge of the roof, the ducts will have to come vertical out of the roof and then horizontal so the exhaust fans won't be hanging over the edge of hte roof. There fans look like they are going to pull too much air. The make-up air is not adequate for the amount of exhaust, plus there will not be 10 feet between the intake and exhaust air. The hoods and fans are from Captive Aire, but there is no job # on anything, so I cannot verify if the fans are matched to the hoods and appliances. We do not even have the complete appliance list yet. I really wish the end user had made some inquirey before starting this job. I will have to have the suppression system tank bracket custom made for the job. I have no idea where we will get enough room to mount our tank, or how we will run our pipe so as not to interfere with the kitchen equipment.

Ivinni · 09-13-2008, 02:42 PM

Quote:

Originally Posted by fireguy

I usually use the 3M 15A on ducts. It is expensive, but faster and much less expensive than framing a chase and putting in a layer of 5/8 sheet rock and getting it mudded. In Oregon, we are allowed to use a single layer of 5/8 for a 1 hour rating. For complete hood installs, I use a local sheet metal shop. They use another brand, 2 " and only a single layer. It is less expensive than 3M. Some day I will write down the name, and change over from 3M.

I have already told my customer that I strongly recommend he use the 3M insulation for the ducts. This kitchen part of the job was speced and started by another company. they installed low proximity eyebrow hoods. they should have used canopy hoods. There will problems with the clearances, head room and clearance to combustable. The duct is at the edge of the roof, the ducts will have to come vertical out of the roof and then horizontal so the exhaust fans won't be hanging over the edge of hte roof. There fans look like they are going to pull too much air. The make-up air is not adequate for the amount of exhaust, plus there will not be 10 feet between the intake and exhaust air. The hoods and fans are from Captive Aire, but there is no job # on anything, so I cannot verify if the fans are matched to the hoods and appliances. We do not even have the complete appliance list yet. I really wish the end user had made some inquirey before starting this job. I will have to have the suppression system tank bracket custom made for the job. I have no idea where we will get enough room to mount our tank, or how we will run our pipe so as not to interfere with the kitchen equipment.

I certainly do not want to tell you your business so take the following with a grain of salt. Eventhough the inspectors allow you to do this, it is still contrary to the code. UL or any other testing agency does not have a 1 hour fire rating for a one sided wall (if I am understanding you correctly), as walls have two sides.

You will be liable in a court of law should there ever be a fire and the attorneys find out you violated code, whether your violation caused damage or not. You will still be sued and have the expense of defending yourself.

Looking at it from the other direction (my sales technique for customers who want to cheat in order to save money), "Sir, you are putting yourself at great risk financially if you do not do this per code", then you make money (more) when they decide to do it properly. Fear is your friend

Unforgiven · 09-18-2008, 05:44 PM

I use Hoover PyroGuard (google it, available through most lumber yards) plywood when needed. Keep in mind that materials aren't rated, assemblies are. If it is to serve as a firewall you will need a UL assembly diagram.