How to fireblock framing

Termite

You beat me to it. That's the Murphy's law pipe. Totally fine to do that. Very common in TV rooms with ceiling projectors or when audio/video components are in another area.

DIY_JC

I've thought of putting 3" pvc through the firestop... but honestly, I wouldn't want to cap it. If I cap'd it, then I would have to tear the walls apart again next time I added/changed cables. Obviously, that would defeat the firestop. Slightly better I suppose would be to stuff fiberglass into the pvc, perhaps in addition to fire-caulk around the outside of the pipe.

If you did cap it, do people drill a hole through the cap to allow the wires through?

Scuba_Dave

I was thinking that the caps would be in an area that would be accessible. IE basement to attic. For me I have a PVC pipe going from the basement to a knee wall area on the 2nd floor. I can then run wire to the Master bedroom, 2nd bedroom, or bathroom. The dormer on the back prevents easy access to the other 1/2 of the rooms. When I redo the kitchen I want to add a PVC access pipe for the addition

fireguy

Are you going to list the temperature requirements for various parts of the project, such as the temps around B vent, smoke pipe, chimenys? And the UL ratings such as E84?

When you are done with this little project, are you going to do one on Fire Stopping? Especially in commercial jobs.

Termite

The fireblocking requirements I'm discussing here are based on R602.8 of the International Residential Code. ASTM E84 and UL 273 are surface burning tests that don't really come into play for this application because R602.8.1 specifically specifies the allowable materials for residential fireblocking (wood, plywood, sheetrock, etc).

Clearances to gas vents, fireplace vents, and chimneys are often an issue with firestopping materials. I'll try to get pics to demonstrate that as this thread progresses. B-vent clearances have already been discussed.

As for another thread on firestopping, I'd like to do one, but it really wouldn't be beneficial for most on this site since we're geared toward residential DIY. In this thread I do plan to eventually touch on intumescent caulk and its virtues in the garage to maintain the required fire membrane at penetrations.

RDS

Thank you for this, termite. I recently spent a lot of time puzzling over fireblocking guidelines for my DIY bath remodel, and what you've provided here is clearer than anything else I found.

Maintenance 6

Firestop products work in one of two ways. Intumescence or endothermy. When an endothermic product is exposed to fire it develops an insulating char on the surface. The char protects the material beneath it from further attacks by fire. Foams are endothermic. The other method is by intumescence. In this method, when the firestop product is exposed to high heat, it expands to fill any gaps, thus preventing the spread of heat and smoke. Firestop caulks and sealants can be either endothermic or intumescent. If you were to expose a firestop product to relatively high heat under a non fire condition, it would activate the fire proofing properties and expend thier usefullness. Further, firestop products are formulated to activate and provide protection during a relatively short timespan. Continued exposure to a moderate amount of heat over a long timespan is not what they were designed for.

Termite

No problemo. Glad it helped. Trust me, I see the puzzled looks that builders give me when faced with fireblocking, so your average DIYer doesn't have any idea what to do.

Sometime soon I'll get some more pictures to get into further detail on various fireblocking situations.

Termite

Interesting. It is my understanding that intumescent products expland (or intumesce) when heated, providing an endothermic barrier. Although the fireblocking foams do posess limited endothermic properties, they're not on par with an intumescent product. That's why they are not listed for firestopping, just fireblocking.

As far as firecaulks/fire sealants for firestopping go, there are intumescent products and non-intumescent products. The way I understand it, both perform endothermically to prevent the passage of fire for the listed time of the assembly, even only one expands.

I can tell you for sure that the fire foam doesn't do very well against a propane torch!

ponch37300

Great write up Termit. Here is a link to the hilti site which has a great selection of firestopping products. I worked for a commercial construction company for a while and we used these all the time in hospitals. Mostly the fire caulk for penatrations. http://www.us.hilti.com/holus/module...jsp?OID=-18981

Termite

Right on. Hilti is a prominent manufacturer of firestopping products. Specseal and 3M are also commonly used and specified.

These are normally not used much in single family residential applications though, since they're for firestopping, not fireblocking. Plus, they're very expensive ($12/tube or more).

Maintenance 6

Termite......... you should know that isn't a proven scientific test method.

Agreed. Most firestop products ultimately act as endothermics. During a fire, purely endothermic fire stop products, will remain in the same configuration as they were installed but char over for protection, while intumescent products will expand to fill voids. During a fire, a bundle of wires for example, sealed with an endothermic, such as foam will burn away leaving a hole for smoke and flame to pass through. The sealant has remained intact, but the penetrating item has burned away. The fire seal has ultimately failed. An Intumescent sealant will expand as the wires begin to burn away and close the space, blocking smoke and flame. I realize this may be getting a little too in depth for a DIY site. For what it's worth, 3M and Hilti both offer UL rated firestop systems that use foam.
For construction joints, foam is a good product. For pentrating items, particularly ones that can burn away, an intumescent sealant should be used.

Termite

I'm all about doing redneck tests!

Funny thing about intumescent material is that so many tradesmen that install the stuff have no idea how it works or what it does. It is always fun to hit a drop of it with the torch and watch them get all excited.

Termite

Ok, stopped and took some pics on my way home today.

This one shows where the electician drilled through the top plate of a wall that will be sheetrocked on both sides. Those holes must be filled with fire foam or intumescent firecaulk.

The second pic shows a wire hole and a pipe in the top plate, both of which must also be sealed. In rated/commercial construction, you'd have to use intumescent firecaulk around the PVC because it will melt in a fire. That isn't necessary in single family residential homes though.

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Termite

This shows a bottom plate with copper and PVC pipes penetrating it. Also need to fireblock these.

(by the way, the PVC pipe protection is inadequate...a larger plate will be required on both sides)

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