Clearance to combustibles reduction Via.... steps explained.. Please confirm...

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Soup

New Member
Sep 27, 2020
30
Where it gets cold
Hello,

so I had found a technical bulletin..... for Durock.... Sept.... 2004

The technical bulletin says this...:

__________________________________________________________

DESCRIPTION
Space-saving DUROCK®Cement Boards are listed byUnderwriters Laboratories, Inc., for use with UL-listed solid-fuel room heaters and fireplace stoves. Used as a wall shield, DUROCKCement Board reduces by one-half themanufacturer-specified clearance (minimum 12") between the room heater or stove and a combustible wall surface.DUROCKCement board may also be used as a floor protector in place of one layer of 3/8" thick millboard.*

**Having a thermal conductivity of k ≤0.84 Btu in./(ft.2? °F) in the minimum dimensions specified by the room heater/stove manufacturer

So................... on the front of this bulletin........ they had a drawing....(picture)
of a wall behind a stove...... showing Durock behind a brick venneer......

Taking all this in........

with the idea of bringing stove closer to the wall.......(A jotul f118)
moving from 36" to no closer than 18".........

What is necessary to accomplish this with the use of Durrock........
I can fabricate anything and assemble... what needs to be done...
I have all the tools.......
I want to do the requirement...... and not go overboard......
It is more of a sense of piece of mind....... I am trying to achieve... by my actions......(safety yes.... but, in knowing that it is the right thing)

The blurb says "USED AS A WALL SHIELD"

can anyone elaborate....
Thanks, Soup
 

Attachments

  • TB28 Durock Bulletin.pdf
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Soup

New Member
Sep 27, 2020
30
Where it gets cold
Figuring on putting durock on metal stud... with
opening at bottom and top..... figuring using
metal vented soffit strip at floor's base....
and at point where ceiling and wall meet....

ceiling ----------------------------------------------------------------| |
vented soffit grille
---------------------------------------------------------------------------------| |
Durock


----------------------------------------------------------------------------------| |
vented soffit grille

floor -------------------------------------------------------------------------------| |

combustible surface will be behind metal stud > 1" behind.........

So this Durock............ surface.......
what are the finishing options for it........

Use of high temp thinset??? with
what kind of finishing options....(any requirements??) ceramic? porcelain???
are there UL requirements.....(to follow??)

Does this help those that have viewed.... this.... thread...
to offer some input....

Soup
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,791
South Puget Sound, WA
This primer may also be helpful:

You don't have to use metal studs to create the air gap, some folks use ceramic 1" standoff or they make their own using 1" pieces of 3/8" copper tubing. Another simple method to create the air gap is to use the 1/2" thick cement board by cutting 3' x 3" strips off the end then screwing two layers of these strips vertically on the studs to create 1" thick firring strips that make the airspace. Just be sure that the wall shield has at least a 1" gap on the bottom and is open on the top so that air can convect freely behind the shield. And note that the wall shield just needs to be non-combustible. Sheet metal on 1" standoffs works find.

Last, if you only want to reduce down to 18" instead of 12" then a brick wall using full brick is sufficient for a 50% clearance reduction.
 

Soup

New Member
Sep 27, 2020
30
Where it gets cold
BG:

You don't have to use metal studs to create the air gap, some folks use ceramic 1" standoff or they make their own using 1" pieces of 3/8" copper tubing. Another simple method to create the air gap is to use the 1/2" thick cement board by cutting 3' x 3" strips off the end then screwing two layers of these strips vertically on the studs to create 1" thick firring strips that make the airspace.
GTK..... thanks!
** Yes, the metal stud will work out then.... in my case it will be easier to do this... as there is a pocket door that needs a wall..
It will sit back behind durrock metal stud. and wall on the other side of the the pocket door
so it will just be framed with metal stud.....

Just be sure that the wall shield has at least a 1" gap on the bottom and is open on the top so that air can convect freely behind the shield. And note that the wall shield just needs to be non-combustible. Sheet metal on 1" standoffs works find.

** Yes, this is great........ USG Durock is considered non-combustible..... see attached...(ASTM E-136-04, BS 476-4 ) pg#4
Will be sure to do the air at bottom and top.....

Last, if you only want to reduce down to 18" instead of 12" then a brick wall using full brick is sufficient for a 50% clearance reduction.
This is nice too.... but ..... takes longer.... and takes up more space..... GTK,,, thanks!

So what about gluing(high temp thinset).......... and tasteful..... decorative tile.... (either porcelain or ceramic)
on the Durrock
Cuz this heat shield poses as a wall also.....

Thaknks, Soup
 

Attachments

  • SUB01_SH_BR_0220_V1-lr.pdf
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