Hello & question regarding hearth construction...

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Duramaximos

Member
Dec 18, 2011
31
Alberta, Canada
Hello,
First time poster here, and very excited to find this excellent site!

I'm the proud new owner of a Jotul F500 Oslo...although it is still on the crate and the planning and intall has only just begun, I can't wait to start burning real wood!

I'm currently in the process of preparing drawings and plans for The City of Calgary (Alberta, Canada) for my permit application. Most all items are checked, however I've hit a road block regarding the Floor Protection requirements.

I have contacted my dealer but they were not able to answer my question to my satisfaction.

The manual states the following regarding Floor Protection:
"Floor protection under the stove must be a UL 1618 type Ember Protector...."
If I were buying a premanufactured Ember Protector this would be easy for me to confirm based on the UL label.

However, I am building my own floor protector to a custom size, so I believe I need to understand what the UL1618 requirements are.

Furthermore, the owners manual does not list a specific R value requirement for standard installation under section 4.1. It only states:
"The Jotul F 500 must be installed on a non-combustible surface extending...(listing various dimensions)"

On the other hand, the Alcove Installation instructions (section 4.3) specify an R value of 1.6 for the floor protector. This is repeated again in Appendix A, where the minimum R value is not stated except for Alcove Installation.

I don't want to make any assumptions, but the manual seems to suggest that only Alcove Installations require an R rated floor pad, and standard installations only require a non-combustable surface. This is in keeping with the simplified response I received from my dealer, who suggested I simply install a 1/2" sheet of Durock and lay tile or slate on top.

My initial concept is as follows:
Existing sub-floor consists of 3/4" OSB over a suspended floor with joists at 19" CTC.
Floor pad to be made from 2 layers of 1/2" Durock, followed by slate tile, set with mortar and filled with grout.
I do want to ensure the finished pad is a minimalistic design - low profile.

Ideally I would like to source a document from Jotul where they specify the R value required for standard (non-Alcove) installation.
I would be greatful for any adivse or suggestions you might have.
Thanks in advance.
 
Your plans sounds fine. Exceed clearances where possible. Here is chapter and verse from the manual - page 7.

Floor Protection
Floor protection under the stove must be constructed of a noncombustible
material for protection from radiant heat, sparks,
and embers.
Individual sections of floor protection must be mortared
together to prevent sparks from falling through to combustible
materials. Any carpeting must be removed from under the floor
protection.


In the U.S. and Canada
The Jøtul F 500 must be installed on a non-combustible surface
extending:
A minimum of 18†(457mm) in front of the stove and the left side
load door (measured from the legs).
And 8†(200mm) on the right side and back of the stove (measured
from side and back panels).
This will result in a minimum floor protection of
56â€W X 50,5â€D.(1422mmx1283mm) See figure 8.
In a rear vent installation the floor protection must also extend
under the stove pipe a minimum of 2†(50mm) beyond either
side of the pipe.

Alternate hearth protection
A hearth pad measuring 46â€wide X 50,5†deep
(1168mmx1283mm)can be used only if the left side door is looked
to prevent use.
When constructing a new hearth or floor pad, consult appendix
a at the back of this manual for alternate materials and
methods.
 
Thank you.
Are you surprised to see Jotul is not recommending a minimum R value for the standard installation?

I mean, if taken litterally, one could glue down a peice of sheet metal and call it good.
 
I would be concerned with OSB as the base. What if you used one layer of plywood then one or 2 layers of Durock with thinset between all layers? For some reason I thought there should be plywood rather then OSB for supporting a stove or am I wrong on this?

Ray
 
Duramaximos said:
Thank you.
Are you surprised to see Jotul is not recommending a minimum R value for the standard installation?

I mean, if taken litterally, one could glue down a peice of sheet metal and call it good.

That's correct. There are several stoves on the market that only requires an ember shield. And there are others that require substantial insulation under or in front of them. It varies with the design and shielding of the stove.
 
I have an Oslo stove. Ember protection is all that is required. My pad consists of 2 sheets of 3/4" plywood with mortar and slate. Works fine, Although the pad in front of the stove does get pretty warm - have measured it up to 130 degrees F. Passed the WETT inspection with no problems.

I recommend that you do purchase the bottom heat shield and the rear shield as well (if you want to get close to a wall).
 
Excellent. Thanks everyone for your quick responses.

nelraq said:
I have an Oslo stove. Ember protection is all that is required. My pad consists of 2 sheets of 3/4" plywood with mortar and slate. Works fine, Although the pad in front of the stove does get pretty warm - have measured it up to 130 degrees F. Passed the WETT inspection with no problems.

I recommend that you do purchase the bottom heat shield and the rear shield as well (if you want to get close to a wall).

The bottom shield is standard with the stove I'm buying, and I did order the rear shield as well - check, check!

Thanks again.
 
nelraq said:
I have an Oslo stove. Ember protection is all that is required. My pad consists of 2 sheets of 3/4" plywood with mortar and slate. Works fine, Although the pad in front of the stove does get pretty warm - have measured it up to 130 degrees F. Passed the WETT inspection with no problems.

I recommend that you do purchase the bottom heat shield and the rear shield as well (if you want to get close to a wall).

+1 . . . as BeGreen and others said only ember protection is needed in most cases so yes, a sheet of flashing would work . . . but would be darn ugly . . . and besides . . . when it is relatively easy to build a hearth with an extra R value to me it makes sense so you can sleep well at night . . . I pretty much did what Neraq described.
 
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