Is Spray Insulation Considered a Fire Stop?

[Greatwhitewing]

My inspector wants blocking above header between joists just inside eves as a smoke/fire block but I forgot to mention I was having spray insulation done (at least the current plan).

Hate to buy 50 feet of 2x12 to cut into 14-1/2" long pieces unless it's really needed

 

[theoldwizard1]

Check with your installer and get a certificate that it is rated as a Fire Stop.

 

[Greatwhitewing]

Check with your installer and get a certificate that it is rated as a Fire Stop.

In trying to keep the post short the installer hasn't been identified yet because a new contractor is just getting started 1/2 way through (long story not getting into now). So I wanted to know now so I could get the blocking in now so I don't hold up the installer.

I am expecting things to move pretty fast now but I will will be doing a lot more myself working with new contractor.

 

[Dragfluid]

One has to wonder why you didn't ask the inspector this question at that time?

AFAIK, closed cell foam will go up like gasoline. Not sure why it would be ok'd as a fire stop. Please correct me if I'm wrong.

 

[dcg9381]

In most cases, no, it's not a fire stop... From an older post:

"Most building codes, including the International Residential Code (IRC), require spray foam insulation (including foam installed on the interior of basement walls) to be covered with a 15-minute thermal barrier. However, if the spray foam is located in a crawlspace or an attic “where entry is made only for service of utilities,” the code permits the installation of a less stringent covering — an ignition barrier rather than a 15-minute thermal barrier.

You can buy foam that is rated as a barrier.

 

[Greatwhitewing]

In most cases, no, it's not a fire stop... From an older post:

"Most building codes, including the International Residential Code (IRC), require spray foam insulation (including foam installed on the interior of basement walls) to be covered with a 15-minute thermal barrier. However, if the spray foam is located in a crawlspace or an attic “where entry is made only for service of utilities,” the code permits the installation of a less stringent covering — an ignition barrier rather than a 15-minute thermal barrier.

You can buy foam that is rated as a barrier.

Thanks, I guess that means cutting up 50 feet 2x12's, kinda sad especially at todays lumber prices.

I can console myself it will add a little more stiffness to floor, at least I can tell myself that because I always believe me.. lol

 

[Dragfluid]

Forgot to mention. I had a bunch of foam exposed in a utility room in the basement. Insurance inspector said "get it covered!"

 

[bigdav160]

some foam have a retarder added

 

[Greatwhitewing]

some foam have a retarder added

I am talking about 50 square feet, 50 linear feet by 12" openings

 

[bigdav160]

I am talking about 50 square feet, 50 linear feet by 12" openings

The person installing the foam can have a fire retarder added. It turns the foam red (ish) so the inspector knows

 

[Greatwhitewing]

The person installing the foam can have a fire retarder added. It turns the foam red (ish) so the inspector knows

Thanks, I hope I have the time to talk to him/her before starting. Sounds like it might be cheaper to add something to the mix vs. 50' of 2x12's plus the time and nails.

 

[jkeyser14]

I am talking about 50 square feet, 50 linear feet by 12" openings

Look at the MSDS. Regular Great Stuff and the Fireblock are the same with the same flame retarders. The only difference is the dye added at a huge cost markup. Don't believe me? Put some of both on a board and hit them with a torch.

 

[Greatwhitewing]

Look at the MSDS. Regular Great Stuff and the Fireblock are the same with the same flame retarders. The only difference is the dye added at a huge cost markup. Don't believe me? Put some of both on a board and hit them with a torch.

By fire block I am talking about wood boards (2x12's) the inspector wants between joists. Again the area is far more than cans of spray can accommodate.

I think SMOKE block is probably a more appropriate term because there is little about a wood frame structure that is fire resistant

I already added fire stop caulking where the wires and pipes go between floors. Yea, it's red probably as an inspection aid.

 

[CraigStu]

This may be a good time to just do what the inspector asks for and move on. I know it's a pain in the ****. We bought a house 7 yrs ago and the finished basement had been done w/o permit. Beautiful work but the inspector said it needed firs tops. Seller had to cut out the top 15 inches or so of the drywall all around the outside walls to install those 2x12s. I actually felt sorry for him but I wasn't going to buy and then it would be my problem.

 

[denson]

perfect

 

[Daniel Dudley]

You are talking about a morning's worth of work, taking your time with the blocking. Either call the inspector, or get to it. Personally, I think it would be easier to just do it and get it done.

You can do it.

 

[aardquark]

Another thing to consider is that a 2x12 is much better at keeping out the critters than foam. soffit areas are easy entry points, especially as building age and materials degrade.

 

[Greatwhitewing]

Another thing to consider is that a 2x12 is much better at keeping out the critters than foam. soffit areas are easy entry points, especially as building age and materials degrade.

Good point

 

[Lassen Forge]

Spray fire stop is a fire blocker - make sure it's approved to use by your building inspector. There are a number of these that are used both for wood and steel construction to protect the material from fire impingement.

Spray foam insulation that is not a fire blocker is a fire accelerant and, when burned, generally a toxic gas producer.

 

[Jlbc212]

Mineral wool insulation in the form of batts or blankets is recognized in the IRC as a fire stop. You may want to consider it as an alternative to wood.

 

[machsnell]

Look at the MSDS. Regular Great Stuff and the Fireblock are the same with the same flame retarders. The only difference is the dye added at a huge cost markup. Don't believe me? Put some of both on a board and hit them with a torch.

So true. I did this. Unbelievably surprised. It should be called fire starter.

My icynene open cell foam will burn but puts itself out.





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