How to fireblock framing

vetting · 03-04-2009, 08:45 PM

Fireblocking aside, is there a problem with insulation touching a heat duct?

**Termite** · 03-05-2009, 12:04 AM

Quote:

Originally Posted by vetting

Fireblocking aside, is there a problem with insulation touching a heat duct?

A heat run, no. Not a problem.

A flue...Big problem. Type B gas vents require a 1" airspace around them, and insulation cannot be piled against them.

n0c7 · 03-05-2009, 06:18 PM

Quote:

Originally Posted by thekctermite

Now, a few scenarios...

This is one that just about every house has. Chases for HVAC vent pipes, plumbing and electrical must be firestopped top and bottom. This picture is not firestopped. See how the vertical chase is open to the horizontal spaces between the floor joists, which allows a fire to move from vertical to horizontal?

Over here you can use fiberglass insulation around hot air ducts just not chimney(type-b vent). I've seen fiberglass shoved into spaces like the picture you posted. Not sure what type of vent that is but you don't want to give people the misconception that they cannot use insulation around ducts. For any electrical running over top or along side ducts, there needs to be insulation between them as well,ad least here in the great white north.

I don't believe firestopping is code(or just not enforced at all) where I'm from as this is the first I've heard of someone going to all of this effort(not to say I disagree with it). I don't believe we have to insulate our ceilings either regardless if its drop ceiling or drywalled. Last basement I finished only had the bedroom ceiling insulated for noise reduction, the rest of the place was drywalled with no insulation in the joists. Inspector did not care and never occured until I read your post that there was more to it. In the case of a ceiling being insulated and drywalled, would you recommend vapor barrier as well, mainly to help hold the insulation in place?

**Termite** · 03-06-2009, 12:32 AM

Quote:

Originally Posted by n0c7

Over here you can use fiberglass insulation around hot air ducts just not chimney(type-b vent). I've seen fiberglass shoved into spaces like the picture you posted. Not sure what type of vent that is but you don't want to give people the misconception that they cannot use insulation around ducts.

That was made very clear in post #92. As stated, you cannot insulate around chimneys or flues, but ductwork is fine.

tophercole · 03-06-2009, 12:09 PM

thekctermite - Great Thread!!

Jsut found it yesterday. I was investigating how to do fireblocking 6 months ago and was dismayed how little there was posted online.

If I may take you up on the offer to post specific problems.

I am starting to finish my basement. Normally the wall is about 2 inches offset form the foundation wall. So I have put 5/8" fire rated sheetrock on the bottom of the joists, spanning from the foundation to the top 2x4 plate.

The issue is, I have an area that I was going to leave unfinished due to some ductwork dropping beneath the joists. This new wall will be 4 feet from the foundation wall. Now, Normally I assume, I could just throw a sheet of 5/8" up there so is no wall smoke could easily get up in the joist bays. But with all the duct work, it would be almost impossible. Would it be OK for this section just to stuff the joist bays with insulation. Maybe only the joist bays with the duct work in them? Again, can it jsu tbe unfaced batts or something else.

Sorry if I am unclear.

I am trying to attach a picture of what I mean. Never attached a picture so I rescaled it. Hopefully you can still see it.

Wildie · 03-06-2009, 01:06 PM

Quote:

Originally Posted by n0c7

Over here you can use fiberglass insulation around hot air ducts just not chimney(type-b vent). I've seen fiberglass shoved into spaces like the picture you posted. Not sure what type of vent that is but you don't want to give people the misconception that they cannot use insulation around ducts. For any electrical running over top or along side ducts, there needs to be insulation between them as well,ad least here in the great white north.

I don't believe firestopping is code(or just not enforced at all) where I'm from as this is the first I've heard of someone going to all of this effort(not to say I disagree with it). I don't believe we have to insulate our ceilings either regardless if its drop ceiling or drywalled. Last basement I finished only had the bedroom ceiling insulated for noise reduction, the rest of the place was drywalled with no insulation in the joists. Inspector did not care and never occured until I read your post that there was more to it. In the case of a ceiling being insulated and drywalled, would you recommend vapor barrier as well, mainly to help hold the insulation in place?

There's a popular TV show, HOLMES on HOMES recorded in Toronto, ON. One segment that I watched, Mike Holmes was building a rec room wall against the foundation wall.
He blocked off behind the headers with fire rated Roxul Insulation. Whether this is a code requirement in Ontario, I'm unsure. However, Mike always claims that he always builds better than what is required by code!

I don't think that ROXUL is distributed in the US.

n0c7 · 03-06-2009, 08:36 PM

Quote:

Originally Posted by Wildie

There's a popular TV show, HOLMES on HOMES recorded in Toronto, ON. One segment that I watched, Mike Holmes was building a rec room wall against the foundation wall.
He blocked off behind the headers with fire rated Roxul Insulation. Whether this is a code requirement in Ontario, I'm unsure. However, Mike always claims that he always builds better than what is required by code!

I don't think that ROXUL is distributed in the US.

I'll watch out for that episode. I've been looking for any fireblocking code requirements for Alberta and have found nothing specifically. Ontario is politician capital of the country so and I've heard many rumors of how much stricter they are(including showing your passport to get into a bar..

).

n0c7 · 03-06-2009, 08:36 PM

Quote:

Originally Posted by thekctermite

That was made very clear in post #92. As stated, you cannot insulate around chimneys or flues, but ductwork is fine.

Noticed that as soon as I posted. Sorry.

Wildie · 03-06-2009, 10:49 PM

Quote:

Originally Posted by n0c7

I'll watch out for that episode. I've been looking for any fireblocking code requirements for Alberta and have found nothing specifically. Ontario is politician capital of the country so and I've heard many rumors of how much stricter they are(including showing your passport to get into a bar..

).

Just if the bar is in Detroit! lol!

**Termite** · 03-07-2009, 05:39 PM

Quote:

Originally Posted by tophercole

thekctermite - Great Thread!!

Jsut found it yesterday. I was investigating how to do fireblocking 6 months ago and was dismayed how little there was posted online.

If I may take you up on the offer to post specific problems.

I am starting to finish my basement. Normally the wall is about 2 inches offset form the foundation wall. So I have put 5/8" fire rated sheetrock on the bottom of the joists, spanning from the foundation to the top 2x4 plate.

The issue is, I have an area that I was going to leave unfinished due to some ductwork dropping beneath the joists. This new wall will be 4 feet from the foundation wall. Now, Normally I assume, I could just throw a sheet of 5/8" up there so is no wall smoke could easily get up in the joist bays. But with all the duct work, it would be almost impossible. Would it be OK for this section just to stuff the joist bays with insulation. Maybe only the joist bays with the duct work in them? Again, can it jsu tbe unfaced batts or something else.

Sorry if I am unclear.

I am trying to attach a picture of what I mean. Never attached a picture so I rescaled it. Hopefully you can still see it.

If the area is accessible and is not space concealed within the walls (a dead space more or less), fireblocking is not required. If there's a door to the area or if the area connects to another unfinished part of the basement then there's no need to rock.

If the space is concealed, it would be easier to fireblock between the joists above the wall's top plate. This can be done with 2x10 blocks, or smaller 2x blocks where things like pipes and ductwork get in the way. I'd recommend packing any remaining voids around the blocks with insulation.

Does that make sense?

tophercole · 03-08-2009, 09:09 AM

>>>
Does that make sense?

It makes sense to me. The space will be accessible. i plan on using it as storage.

Worst case, the 2x10 blocking idea is simple enough. Thanks for your input. I appreciate it.

**Termite** · 03-08-2009, 10:23 PM

If you can walk into the room and look right at the framing, most people will agree that it is not concealed space and therefore does not require fireblocking.

Speedball · 03-29-2009, 01:20 AM

Page 4 Post #48

Fitting the plywood fire blocking as shown........Was this intended / specked as fire blocking or is this just a detailed carpenters work?

....fascinating pictures that bring a whole new idea to a framers mind.

**Termite** · 03-30-2009, 10:14 AM

Quote:

Originally Posted by Speedball

Page 4 Post #48

Fitting the plywood fire blocking as shown........Was this intended / specked as fire blocking or is this just a detailed carpenters work?

....fascinating pictures that bring a whole new idea to a framers mind.

Good question Speedball. Yes, that 3/4" plywood was installed as fireblocking because there are two separate walls there, through which horizontal fireblocking is required at 10' intervals. That particular framer was spot-on with his fireblocking and the work was among the cleanest I've ever seen. Take note of how he notched it between the top plates. Most builders would leave a gap there and fill it with insulation simply because its easier. You can tell that this guy prides himself in doing nice work.

Clutchcargo · 05-07-2009, 03:09 PM

Quote:

Originally Posted by thekctermite

That makes me hungry for smores.

I figured that the fireblocking foam would perform a little better.

There is probably a more scientific basis for comparison between the two...Perhaps having to do with ignition point, time frame from ignition to failure, heat transfer past the fireblock, flamespread, smoke developed, etc.

I read in Fine Homebuilding magazine that Great Stuff fireblocking foam was nothing more than Great Stuff Gaps and Cracks with an orange dye in it.
My local building inspector told me to use the blue can Great Stuff (windows and doors) for fireblocking as it doesn't burn nearly as freely as the red can.
I tested this by putting a torch to both products and he's right, I couldn't get the blue can foam to ignite but the red can product continued to burn on it's own.