It should be blocked off every ten feet. Where you run the services through the blocks fill tightly around with fireblocking material. Expanding foam is not a fireblock.

worthy,

Talk about a picture being worth 1,000 words... that's perfect!

So, if I understand it correctly, a valid fire block is a batt of fiberglass insulation. So I'll meet code if I stuff batts horizontally inside of the upper space along the entire rim joist, as well as vertically between studs at least every 10'?

Oh, before I forget... where would I find the appropriate code book for MD? The NEC code book is in practically every major bookstore, but in that case I knew exactly what book to look for... I don't know in this case.

Thanks!

The link below should help. Maryland has adopted international codes with some modifications--Maryland Building Performance Standards. And these may be altered by individual jurisdictions.

Even if a building inspection is not involved, for your own peace of mind it's worth it to meet Codes, especially those pertaining to fire and safety.

Here is a link that might be useful: Maryland Building Performance Standards

We now have fire-rated expanding foam. It's a paltry $50 per can. It's bright pink so inspectors can recognize it. I work in Loudoun Co, a county that borders Fairfax.
Casey

DAP makes a code-approved fireblocking foam that is about $9.00 for a 10 oz can.

A single can can do an entire story in a modestly sized home.

The 'color' of insulating foams does not guarantee that they are approved as fireblocks.

Several traditional 'yellow' expanding foams are acceptable as fireblocking materials and several 'orange' or other colored expanding foams are not approved as fire-blocks.

Only 3rd party testing of the product determines the foam's suitability for use as a fireblock.

Only it's listing and labeling can be used to determine whether or not the foam is approved...

Never its color alone.

Here is a link that might be useful: DAP Fireblocking Foam

Thanks for updating info on fireblocking foams introduced last year.

For what it's worth, MacGyvers2000, I don't interpret that code language as requiring that the vertical gap behind the studs be fireblocked - just every 10' HORIZONTALLY. Fire gases travel up very fast in a closed chamber, but not really sideways very much. I guess it doesn't hurt, but I would concentrate most on eliminating any upward (or over, then upward) route for the gases to follow.

As far as material goes, I guess fiberglass batts would help slow things down, but I prefer to create solid wood or even drywall blocks. Either should be cut to fit and sealed at the edges with expanding foam or caulk. This is more airtight and both solid wood and drywall will last a while in a fire. Fiberglass won't burn, but it's porous and may get pulled up and out of position by a strong updraft.

My comments are based on my observations of the laws of combustion and a little knowledge of materials. In your case, I would cut some scrap drywall to attach to the underside of the top plate and seal it with expanding foam.

"The 'color' of insulating foams does not guarantee that they are approved as fireblocks.

Several traditional 'yellow' expanding foams are acceptable as fireblocking materials and several 'orange' or other colored expanding foams are not approved as fire-blocks."

I do not think anyone made a claim about the color specifically.

Using a different color will give some indication that not all the foam is the same type.

Fire block rated foam that loks the same as regular foam is not going to be very useful.
When the inspector looks it over he is going to have to rely on someones word that it is the correct foam, or pull a sample for a lab check.

Fire blocking is every 10 feet vertically to limit spread.
If you hold the studs off a basement foundation wall you may need to provide fire blocking all the way to the foundation wall, especially if the floor to floor height is over 10 feet.

So if you use the 1.5" XPS you sshould have the top ridge capped with wood or something though I would think the fg in the joists above should suffice.

Re: fireblocks vertically....the notched 1.5" XPS the HD sells that is meant to attach every two with a fur strip and then have drywall attached...how could you vlock that vertically...the furstrip just sits atop the xps notch and placing wood against the concrete wall between XPS every 10' sort of defeats the purpose of using XPS....

"...placing wood against the concrete wall between XPS every 10' sort of defeats the purpose of using XPS...."

There are plenty of things that are rated as fire stops besides wood.

Safety always trumps efficiency anyway.

...and what might that be....you have 2'wide slotted XPS then another, those two are held in place with a furstrip in the 8' vertical slot...this continues until you hit 10' and then what....vertically that is...

Fire rated foam for one.

"First, your basement ceiling must be completely sheetrocked with the X-rated fire resistant sheetrock - from 'top plate' (over the basement concrete wall) to 'top plate', not just from the new wall to across the basement to the other new wall."

This is NOT the code interpretation I have EVER seen.

Houses are a single fire zone, and the most common required rated wall is between an attached garage and living space and nowhere else.

The 'fire blocking' is NOT to create a fire proof barrier, but to slow the spread of fire.

That is why simple 2x lumber and even unfaced fiberglass insulation are allowed.

You need to ask your AHJ exactly what they want to see, with a code citation so you can look up the exact wording.

A basement in a single family house does not normally require ANY fire rated construction.

I stand corrected. I think maybe I got a little carried away with the techniques of fire blocking. macgyvers2000 opening remarks seemed to indicate that the fireblocking was a personal preference, not as much as a need to meet code. It was later that code was discussed.

Anyway, if the goal is to create a fire rated partition for personal piece of mind, then I still say that using firerated sheetrock offers the best value for the money and effort - if you are going to sheetrock the ceiling anyway. In this case, your only adding a marginal increase to the material cost, with no increase to labor.

to chime in, in my project, I have areas where I have used 1.5" xps and drywalled directly over it. Other areas I framed in front of the XPS. In either area I have a 1.5" top ledge of xps foam exposed. All I need to do as plop a 1.5" strip of drywall over top and I am good to go....would that really make a difference if there was a fire?

Yes, andrelaplume2, plopping that strip of drywall over your xps should make a difference in a fire. I'm not sure exactly what xps is, but assuming it's some kind of insulating foam, it probably will burn, or at least melt and produce poisonous gases if hot enough. From my understanding, drywall will absorb the heat and actually release moisture as it's heated, slowing the spread of flame. That's why the codes specify it for firewalls.

I say it's worth the small investment to cover it while you have access.

"A batt of fiberglass insulation is NOT a valid fire block!!"

A batt of fiberglass most certainly IS a Code-accepted 'valid' fireblocking material.

From the 2006 International Residential Code:

R602.8.1 MATERIALS. "Batts or blankets of mineral wool or glass fiber...installed in such a manner as to be securely retained in place shall be permitted as an acceptable fireblock."

R602.8.11 UNFACED FIBERGLASS. "Unfaced fiberglass batt insulation used as fireblocking shall fill the entire cross-section of the wall cavity to a minimum height of 16" measured vertically. When piping, conduit or similar obstructions are encountered, the insulation shall be packed tight around the obstruction."

------------------

Fiberglass insulation is an code approved method of fireblocking and is used all the time.

Here's our last go round at GardenWeb on this topic.

It's no wonder that in large commercial projects fire blocking is actually a speciality trade.

brickeye said:

"Fire block rated foam that loks the same as regular foam is not going to be very useful.
When the inspector looks it over he is going to have to rely on someones word that it is the correct foam, or pull a sample for a lab check."

No.

If you actually read the listing information on the can of foam, regardless of the color or type, you will find that even 'yellow' insulating foams have nearly identical flame spread and smoke developed index ratings as those that are colored 'orange'.

The fact is that most 'yellow' foams have identical fireblocking charactersistics as most 'orange' foams....and can be used interchangeably from a code inspection standpoint in residential applications (with obvious exceptions, of course.)

---------------
Worthy makes a great point about fireblocking/firestopping in commercial buildings, but fireblocking/firestopping in commercial buildings IS a specialized field.

Protection of penetrations is based on the required fire rating of the wall and floor assemblies based on the Use and Occupancy class and the type of systems being protected.

For helpful information about fireblock protection of penetrations in commercial buildings including listed putties, collars, pillows, wraps, caulks, tapes, matts, and so forth, see the link below.

Here is a link that might be useful: 3M Commercial Firestopping Products

I remember the last go round...just seeking reassurance. To be honest, plopping a strip on the top is an easy endeavor at this point....

I did not understand the foam comment (yellow vs orange). Are you saying both are no good by code, both are good OR either way neither is going to do much for you?

"If you actually read the listing information on the can of foam, regardless of the color or type, you will find that even 'yellow' insulating foams have nearly identical flame spread and smoke developed index ratings as those that are colored 'orange'. "

And just how is the inspector coming along after the installation going to tell what was used?
Check the trash and assume that was what was used?

Things like color marking to differentiate products is very common, and at least gives a better indication that the correct material was used if it is distinctive.

Reviving an old thread... one I came across while doing research for my new home, and wouldn't you know it, I didn't realize it was one of mine until I was halfway through it ;-)

Anyway, still in MD, but now in a slightly different situation. Newer home (built <3 years ago), bigger basement (about 2,200 square feet), taller ceilings (9'+ rather than the older 7'), cast instead of block walls, but still an unfinished basement to play with. This time the plan is to still build the studs a couple of inches from the wall, but this time have someone come in and spray foam all of the walls and nooks/crannies... putting up XPS one panel at a time was too time-consuming in a basement that was 1,000 square feet, so doing it in a space twice that just seems painful.

So, the new questions:

1) Due to the higher ceiling, is any form of blocking necessary between studs at the wid-way point (i.e., a 14.5" long 2x4 nailed between two vertical studs at the 5'-high point), or is that typically done just for structural strength? I'm assuming rock wool stuffed in a vertical cavity every 10' and filling every cavity above the top plate is still valid in terms of blocking.

2) If I do spray, is it a valid block if the foam expands to completely seal between the wall and top plate (and is the 10' rule satisfied in a similar manner if it expands completely between the wall and each stud), or must I block using another method (like a strip of drywall) and let them spray either side? Essentially, is the typical spray foam considered fire blocking, or is it merely rated for insulation?

Thanks!

Fire blocking is for between floors. You don't need any.

Lightly glue sheets of XPS to the walls. Attach a 2x4 top plate to the floor joists. For the bottom plate, lay a strip of tar paper on the floor, then fasten down the bottom plate with blue screws, anchors, etc. Then frame the wall, and add additional insulation.

Huh? I have to segregate the floor joists above me from the walls I'm building, which means a block between the joists and the top plate. I was hoping the foam would handle that, but I wanted to verify before skipping that step.

And as I said earlier, I do NOT want to do XPS paneling due to the installation time involved. Having someone come in and spaying foam would be a one-day affair.

Foam sealant is not true "fireblocking"; its purpose is to seal cracks and holes in the required fireblocking for as long as the fireblocking is intact and is usually called "fire block sealant".

The required foam sealant is not fire-rated or non-combustible but has to meet certain flame spread and smoke-developed index restrictions and remain intact in certain tests. The sealant commonly sold at stores can only be used in residences. A fire-resistance-rating can only be applied to tested wall or floor/ceiling assemblies that separate spaces. Materials or devices that seal penetrations in fire-resistance-rated assemblies are called "fire stopping". Many years ago before consolidation of codes and separate residential codes fireblocking and firestopping were sometimes used interchangeably.

In some jurisdictions the bottom of I-joists above a basement must have a layer of drywall or the joists must be protected by an intumescent coating.

Fire blocking is not needed or required at the mid point of the studs; that might happen in above-grade exterior walls when exterior sheathing has been applied horizontally.

You only need to install a top plate or approved panel against the floor joists that extends from the exterior foundation sill to the front face of the new studs or you could use a 2x4 top plate and fill the space between it and the foundation sill with fiberglass or mineral wool insulation.vthe intent is to prevent hot gasses from easily passing from the wall cavity to the ceiling cavity. That could also be achieved with blocking between the floor joists above the new top plate. Review the options with the inspector to save work and cost.

Spray foam insulation would be just as effective; it just isn't listed as firestopping in the building code but the inspector might believe it is equivalent if it fills most of the cavity. Any spray foam whether it be insulation or sealant must be protected with a thermal barrier that would remain intact for 15 minutes.

Just to answer one of the questions - there should no additional mid-point fire-block required for a 9 foot ceiling. At 10' height or greater it is required by most code, but 9 feet is fine.

Bruce

JDS/Bruce, thanks for the replies. After my last post I did some more digging and somewhat answered my own questions.

The blocks I've seen in the middle of the wall were essentially for structural rigidity (where I could confirm that), but I did come across mention of the blocking being necessary if the wall was >10' high... reasoning being similar to the 10' horizontal blocking, which clarified it for me. Essentially, anything over 10' would need a block at a maximum of the 10' mark, or somewhere above the floor so the two vertically stacked spaces were each <10'.

My current intention is to use 3/4" ply above the top plate to the exterior sill plate, and likely to rip a PT 2x4 to the appropriate width to make the stud-wall-to-cement-wall seal every 10'. Once done, I'll have someone come in and spray some closed-cell foam.

A final question or two, and then I think I'm good... is it necessary to seal all of the edges with caulk? My gut says yes as I know how much of a blowtorch a small hole can turn into with the vacuum power of a confined fire, but I wanted to confirm before going to all of the trouble. If so, can standard caulk be used or must it be fire-rated?

You are over thinking this detail. You are probably going to place insulation in the joist cavity against the sill plate. If it extends to the new wall the fire blocking requirement between the wall and the ceiling cavities should be satisfied. Use mineral wool if you want to increase the protection. Of course, get the building inspector's approval. There are more important life safety issues in a house, some of which are not mentioned in the building code.