Heart pad construction advice?

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TomInNH

New Member
Aug 14, 2011
5
Seacoast, NH
I plan to build a hearth pad for the new Jotul Oslo 500 that I will be getting soon. It will be in a corner, the walls are drywall, and the floor is very nice hardwood, which I would like to preserve underneath. It is my understanding that the Jotul Oslo only requires non-combustable floor protection, not any specific R-value?

My current plan is: a layer of 3/4 plywood, one or two(?) layers of durock cement board, then using thinset to attach flat rocks/slabs (2"-3" thick) from a landscaping company. I want to get one big, flat rock that is bigger than the stove, and put that in the center, so the stove is entirely on a single stone. Then break up other stones as needed to fill in the surronding area. I would use 3"-4" oak to trim the edges of the pad, attaching them to the plywood and durock before putting the thinset and stone down, so I can try and get the stone level with the trim. Size will be 6'x6' with the corner cut off at 45 degrees at 3' out from the walls, which should be way more clearance than the stove requires. No plans to do anything with the walls right now.

Does this all sound reasonable? Any advice or criticism? I've never done any cement or tile type work before so this is uncharted territory for me!
 
Just an FYI - the side loading door is supposed to be locked if the F500 is corner installed. Is there any chance of installing it so that the side-door has an adequate hearth and clearance?
 
BeGreen said:
Is there any chance of installing it so that the side-door has an adequate hearth and clearance?
Click to expand...

I wish there was. Unfortunately, to get the 36" clearance from the wall to use side door, it would have to point away from the living area, and I want to be able to watch the dancing flames on cold nights. :)

The right side loading design of the Jotul 600 would work, but I dont care for the double doors and the removable handle is a pain.
 
TomInNH said:
I plan to build a hearth pad for the new Jotul Oslo 500 that I will be getting soon. It will be in a corner, the walls are drywall, and the floor is very nice hardwood, which I would like to preserve underneath. It is my understanding that the Jotul Oslo only requires non-combustable floor protection, not any specific R-value? Correct . . . but adding a layer or two of cement board should in theory give you a little more R value protection which certainly cannot hurt things.

My current plan is: a layer of 3/4 plywood, one or two(?) layers of durock cement board, then using thinset to attach flat rocks/slabs (2"-3" thick) from a landscaping company. I want to get one big, flat rock that is bigger than the stove, and put that in the center, so the stove is entirely on a single stone. Then break up other stones as needed to fill in the surronding area. I would use 3"-4" oak to trim the edges of the pad, attaching them to the plywood and durock before putting the thinset and stone down, so I can try and get the stone level with the trim. Size will be 6'x6' with the corner cut off at 45 degrees at 3' out from the walls, which should be way more clearance than the stove requires. No plans to do anything with the walls right now. Sounds pretty similar to what I did . . . only I used two layers of plywood and a single layer of 1/2 inch cement board with slate tile (odd sizes) attached to the sheetrock and I was cheap and used pine for the edging. Going a little bit bigger is almost always a good idea . . . I sometimes wish I had built mine even bigger than I did -- when the cats are lying in front of the Oslo on the hearth sucking up the heat I am always tempted to join them, but the hearth just isn't big enough for me to curl up on to it. In any case, going a bit bigger again gives you a little extra safety for any embers that may spit out or coals that may roll out accidentally.

Does this all sound reasonable? Yes Any advice or criticism? I might go with another alternative to the Durock . . . the original stuff was good . . . folks here keep going back and forth on the new stuff in terms of whether it is good for hearths. Go slow. Plan thinks out. Make sure your stove will line up correctly . . . give yourself a little extra space for things (i.e. stove placement on the stone, stove placement on the hearth) in case you have to move things over a dite . . . make sure you clean the grout off in a timely fashion if you use grout.) I've never done any cement or tile type work before so this is uncharted territory for me! There's a good how-to step-by-step guide located at hearth.com . . . takes you through the steps on how to build a hearth that worked well for me . . .
Click to expand...
 
The hearth for my Equinox is being fabricated as we speak. It's gonna be 80 x 51. Lots of room for the side door, tools and maybe some wood.
 
TomInNH said:
BeGreen said:
Is there any chance of installing it so that the side-door has an adequate hearth and clearance?
Click to expand...

I wish there was. Unfortunately, to get the 36" clearance from the wall to use side door, it would have to point away from the living area, and I want to be able to watch the dancing flames on cold nights. :)

The right side loading design of the Jotul 600 would work, but I dont care for the double doors and the removable handle is a pain.
Click to expand...

I hear you. We strongly considered the Oslo and wanted to install it, but for the side door issue. Instead we got the Castine, which worked well, but needed frequent refills with our softwood. If the F600 would work for you clearance wise (it wouldn't for us), then I wouldn't let the split doors be a show stopper. Or consider a different make stove? There are nice alternatives like the Hearthstone Bennington, Quadrafire Cumberland Gap or the Napoleon 1400C. The PE Alderlea has worked out great for our corner install.
 
I would make sure you can actually find one flat stone for your stove. If it is not flat and if it has imperfections in the top surface at the corners, your stove will not be level. It may want to rock or maybe not sit on all four legs?? Not sure what it would do but could be a problem??

I too will be building a corner hearth for a Oslo 500. I plan to use tile and plan to make it approx 54" by 54". The six feet that you plan seems large to me, but many have said bigger is better. We do not have that much realestate to use in our living room. Planning to have the stove corners at 14" from the walls (minimum distance is 13"). Drawing the stove dimensions and stove pipe on the floor along with a couple different hearth sizes has helped me picture what we want and need for the hearth size.

Good luck.
 
better check , i think the oslo needs some r value in the hearth, if you go on the jotul website you can consult the manual. I too didnt want to mess up my hardwood so i but in this order from the floor up 1/4 inch styrofoam, 5/8 plywood 24 gauge steel, durrock, micore 300, another layer of durrock then 1.5 inch bluestone. only thing i would do different is i may have made it higher cause i notice that people really like to sit on the stone and warm up after coming inside
 

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All floor protection materials must be non-combustible ie. metal,
brick, stone, mineral fiber boards). Any combustible material may
not be used.
The easiest means of determining if a proposed alternate floor
material meets requirements listed in this manual is to follow
this procedure.
R-value = thermal resistance
k-value = thermal conductivity
C-value = thermal conductance
1. Convert the specification to R-value;
a. If R-value is given, no conversion is needed.
b. If k-value is given with a required thickness (T) in inches:
R=1/k X T.
c. If C-value is given: R=1/C.
2. Determine the R-value of the proposed alternate floor
protector.
a. Use the formula in Step 1 to convert values not expressed
as “Râ€.
b. For mul t iple layer s, add R- values of each laye r to
determine overall R-value.
3. If the overall R-value of the system is greater than the R-value
of the specified floor protector, the alternate is acceptable.
Example:
The specified floor protector should be 3/4†thick material with a
k-factor of 0.84. The proposed alternate is 4†brick with a C-factor
of 1.25 over 1/8†mineral board with a k-factor of 0.29.
Step A. Use formula above to convert specifications
to R-value. R=1/k X T= 1/.84 X .75 = .893
Step B. Calculate R of proposed system.
4†brick of C-1.25, therefore
R brick = 1/C = 1/1.25 = 0.80.
1/8†mineral board of k = 0.29 therefore
R mineral board = 1/.29 X 0.125 = 0.431
Total R = R brick + R mineral board=
0.8 + 0.431=1.231
Step C. Compare proposed system R = 1.231 to specified R of 0.893.
Since R is greater than required, the system is acceptable.
Definitions:
Thermal conductance =
C = Btu = W
(hr)(ft
2
)(F) (m2
)(K)
Thermal conductivity =
k = Btu = W = (Btu)
(hr)(ft
2
)(F) (m2
)(K) (hr)(ft)(F)
Thermal resistance =
R = Btu = (m2
)(K) = (Btu)(inch)
(hr)(ft
2
)(F) W (hr)(ft
2
)(F)
Alcoves require use of a bottom heat shield and hearth protection
having a minimum R-value of 1.6.

The R value in red is the one i assumed was required by jotul. perhaps i read it wrong but nothin bad about over building right?
 
TomInNH said:
I plan to build a hearth pad for the new Jotul Oslo 500 that I will be getting soon. It will be in a corner, the walls are drywall, and the floor is very nice hardwood, which I would like to preserve underneath. It is my understanding that the Jotul Oslo only requires non-combustable floor protection, not any specific R-value?

My current plan is: a layer of 3/4 plywood, one or two(?) layers of durock cement board, then using thinset to attach flat rocks/slabs (2"-3" thick) from a landscaping company. I want to get one big, flat rock that is bigger than the stove, and put that in the center, so the stove is entirely on a single stone. Then break up other stones as needed to fill in the surronding area. I would use 3"-4" oak to trim the edges of the pad, attaching them to the plywood and durock before putting the thinset and stone down, so I can try and get the stone level with the trim. Size will be 6'x6' with the corner cut off at 45 degrees at 3' out from the walls, which should be way more clearance than the stove requires. No plans to do anything with the walls right now.

Does this all sound reasonable? Any advice or criticism? I've never done any cement or tile type work before so this is uncharted territory for me!
Click to expand...

http://www.jotul.com/FileArchive/Technical Documentation/Wood Stoves/Jøtul F 500 Oslo/Manual_F_500_USA_P15_310111.pdf ... or if you don't to copy the previous url click this one: http://tinyurl.com/3wh4tzm

Look at page 20 I think you need more than just ember protection and must meet a certain R-value... The way Jotul presents the info is a bit confusing and they mention a floor protector earlier in the manual but that pad meets the R-value so you must build to meet or exceed that value in that pre-made pad..

Ray
 
I've seen that part of the manual, but there is no specific R value listed for the stove, just that number used in the example calculation. You think they'd spell it out a bit more directly. And indeed they do, I looked at a 10 year old Joutl 600 and that page of the manual that was with it had all the same content, except there was an added bit in bold saying something like "This model stove requires floor protection with an R value of xxxx"

Furthermore, the "experts" at three local woodstove stores, all said that the oslo just requires non-combustable, no R-value req.

I think a call to Jotul is in order to clear this up.....
 
TomInNH said:
I've seen that part of the manual, but there is no specific R value listed for the stove, just that number used in the example calculation. You think they'd spell it out a bit more directly. And indeed they do, I looked at a 10 year old Joutl 600 and that page of the manual that was with it had all the same content, except there was an added bit in bold saying something like "This model stove requires floor protection with an R value of xxxx"

Furthermore, the "experts" at three local woodstove stores, all said that the oslo just requires non-combustable, no R-value req.

I think a call to Jotul is in order to clear this up.....
Click to expand...

I think you're right after rereading the Jotul manual all you need is ember protection just like my T-5.. I used 2 layers of durock with the seams all offset and all layers thinset together followed by porcelain tile.. Just make sure your inspector understands this beforehand if you're being inspected like I did.. I gave the details on the permit and it was approved providing I followed my own details..

Ray
 
For most installations the F500 only needs ember protection. Alcove installations require use of a bottom heat shield and hearth protection having a minimum R-value of 1.6.
 

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As stated it can be a little confusing but several years back I checked with the dealer and they confirmed only ember protection was needed for the Oslo for a non-alcove installation with the Oslo . . . of course it never hurts to add a little R value into a hearth in my own opinion.
 
Agreed, if you are a hearth.com addict you may be changing stoves more frequently than intended. :red:
 
BeGreen said:
Agreed, if you are a hearth.com addict you may be changing stoves more frequently than intended. :red:
Click to expand...

That is a really good point!
 
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