Flue Mortar

[Corey Friedman]

Hello All,

Is anyone familiar with the using the product "Fire Block FB 136" made by 3M for joining clay flue tiles in a masonry fireplace?

This product was used in a vertical flue between the clay flue tiles and oozes out slightly to the interior of the flue at the joints.

I am not familiar with this product being used in this application.

This does not involve an standard H.I.

Thanks

Corey

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[Joseph Ehrhardt]

Thats for sealing penetrations in construction assemblies, I know of nothing but mortar for the compressive strength for stacking those clay flue pipes on each other, if I understnd what your seeing.

[Raymond Wand]

3Mâ„¢ Fire Block Sealant FB 136:*3Mâ„¢ Fire Block Sealant FB 136

Applications: Use 3M™ Fire Block Sealant FB 136 to seal interior construction voids around wires, pipes, HVAC ducts and vents, in wood or steel framed non-rated construction. May also be used around chimney, fireplace and other framing gaps. Not for exterior use.

[Jerry Peck]

All of the above is good information, and Raymond provided a good link to information on it - here is another link: http://multimedia.3m.com/mws/mediawe...heet4327-6.PDF

I suspect that someone read the information and saw "Chimneys & Fireplaces" at the bottom of the list and did not considered how it was to be used with chimneys and fireplaces:
- A P P L I C A T I O N S
- - 3M Fire Block FB 136 is ideal for use in residential (single, two-family and combustible) construction in areas that require sealing to maintain the integrity of a fireblock. 3M FB 136 can be easily applied with a standard caulking gun, pneumatic pumping equipment or simply a putty knife and/or trowel. It adheres to virtually any material, including wood, masonry, metal and plastic. It is gray in color and applies like conventional caulk.
- - - Wires, Cables & Conduit
 - - - Plumbing
 - - - HVAC Ducts & Vents
- - - General Construction Gaps
 - - - Chimneys & Fireplaces

[H.G. Watson, Sr.]

Hello All,

Is anyone familiar with the using the product "Fire Block FB 136" made by 3M for joining clay flue tiles in a masonry fireplace?

This product was used in a vertical flue between the clay flue tiles and oozes out slightly to the interior of the flue at the joints.

I am not familiar with this product being used in this application.

This does not involve an standard H.I.

Thanks

Corey

Your description is somewhat confusing. Please clarify location. Can we assume you meant Chimney location not fireplace (smoke chamber, firebox) location, as you stated?

What has been installed in the masonry fireplace?
What will be installed in the masonry fireplace?

What has been installed in the Masonry Chimney inside the clay tile flue (Listed Chimney Liner System or Listed factory-built chimney system listed for installation within masonry chimneys, for example)?
What will be installed in the Masonry Chimney clay tile flue?

What is the size and type of clay flue tiles (round, square, rectangluar)?, What is or will be the clearance between the listed liner system or factory-built chimney system and the clay flue lining and this material?

This material is not an equivalent to a medium-duty refractory mortar (ASTM C 199, Standard Test Method for Pier Test for Refractory Mortars).
it is also not equivalent to a high-temperature (2000 degrees F - 1093 degrees C service rating) insulating mortar.

HTH.

[Bob Harper]

HG is correct. This is a 'sealant' used for fireblocking. If this chimney is to be built under the IRC, then the ASTM C-199 refractory mortar is required. If built to NFPA 211, then a medium duty non-water soluble calcium aluminate refractory cement mixture is required. Regardless, the joints must be struck with no protrusion into the flue, which causes turbulence and reduces the effective flue area.

This product is NOT suitable for setting flue tiles.

[Corey Friedman]

Hi All,

Thanks for the replies. I am very familiar with the product and its uses for traditional fireblock applications such as pipe penetrations through framing during construction including fireblocking around chimneys and fireplaces.
No issues with that.

The application this was used in is inside the chimney between the flue tiles. I have never heard of this or seen this. Nothing in their specs indicate that the product can be used for this application.

For those unclear by my previouos description, this is a typical masonry fireplace. The flue liner is vitrified clay. I think the clay tiles are 8"x12" but the size doesn't matter. The flue liner clay tiles are stacked one on top of another just like any other typical vertical flue extending upward from the top of the smoke chamber to the vertical end height of the chimney.

The fireblock caulk is placed on the top horizontal lip of the clay flue tile before the next vertical section of flue liner is placed on the one below it.

It is my undertanding that this product is not for this application. No question about its use as fireblock inside the house as part of required fireblocks in the framing. Never seen it between clay flue tiles.

Thanks

Corey

[Corey Friedman]

HG is correct. This is a 'sealant' used for fireblocking. If this chimney is to be built under the IRC, then the ASTM C-199 refractory mortar is required. If built to NFPA 211, then a medium duty non-water soluble calcium aluminate refractory cement mixture is required. Regardless, the joints must be struck with no protrusion into the flue, which causes turbulence and reduces the effective flue area.

This product is NOT suitable for setting flue tiles.

Hi Bob,

Thanks for the input. I agree about ASTM C-199 and that was the basis for me knocking this installation in the first place since the product does not meet that requirement.

I just wanted to make sure that I wasn't overlooking some weird spec or application of the product.

I looks like we are all in agreement.

Thanks

Corey