Hearthpad height - 4" or 6" - what do you think?

[NH_Wood]

Hey all! I'm going to build a hearthpad in the next couple of weeks. A Hearthstone Mansfield will adorn the top! So.....what do you think - use 2x4's or 2x6's? The stove sits fairly low, so was thinking that raising it 6" + the plywood, durock, tile, would be nice for loading, but....didn't want to go too high - just looking for advice. Thanks! Cheers!

 

[BrowningBAR]

Hey all! I'm going to build a hearthpad in the next couple of weeks. A Hearthstone Mansfield will adorn the top! So.....what do you think - use 2x4's or 2x6's? The stove sits fairly low, so was thinking that raising it 6" + the plywood, durock, tile, would be nice for loading, but....didn't want to go too high - just looking for advice. Thanks! Cheers!

I'm a fan of the hearth pads being as thin as possible (while still being within code/clearances). I just like the look better. Your opinion may vary, though.

 

[Dakotas Dad]

we did ours at 5 1/4 total inches. It's ok, and does/looks the way we want.. but it is just a bit to low to actually sit on, if you are into that.. the stove is bit higher to load then the fireplace was, so that's good, although I have already learned that you don't spend near the time loading / fussing with it compared to the fireplace.

you mention 2x4' and 2x6's and plywood... are you sure you can use wood products in your hearth build? I know mine requires all non-combustibles for the hearth construction. But some only require ember protection which would mean just the durock and tile would do..

 

[BrowningBAR]

Without potentially jinxing an upcoming purchase, the Heritage manual says that the hearth pad needs to have an R Value of 1.2. Can someone educate me in terms of how to measure 1.2 when it comes to R Value? (or point me to the right search terms on this forum to bring up the right threads)

What I have found states the following:
"The R-value is basically the opposite of the U-factor. A single pane of glass, for example, has an R-value of 1.2 and a U-factor of 0.84, while a double pane has an R-value of 2 and a U-factor of 0.049."

So, what does this mean in terms of building a hearth pad? Would a half inch thick slab of granite (for example only) laying on top of a wood floor meet the requirements?

From the Hearthstone Heritage Manual:

HEARTH REQUIREMENTS AND FLOOR
PROTECTION
Combustible flooring must be protected with a
covering of noncombustible material with an R-value
of 1.2 (slate, marble tiles, or other noncombustible
material can be used for this purpose). The floor
protection must extend beyond the body of the
stove at the minimum as follows:
• LEFT SIDE 16” (41 cm)*
• RIGHT SIDE 5” (13 cm)
• REAR 2” (5 cm)**
• FRONT 16” (41 cm)*

 

[pyper]

My finished surface is about 4.5"

I wish it were higher -- I wouldn't need to kneel as much.

 

[Dakotas Dad]

BB,

I just went by the chart in the manual for our stove.. and made sure I had "built up" enough r value to reach our needs..

I know for our stove, on page 10 there is a discussion of what values different materials have, and suggestions of how to use them..

wonderboard/durock has a r value of .2 per 1/2 inch, so two layers there gets you to .4

a 1/8 inch gap between would get you another .92 r so that's "r" 1.32 right there... then your tile or stone or whatever on top...

 

[John_M]

My hearth pad is 11.5" high and I could easily go up another inch or two. For me, the elevated pad eases the wood loading process and allows a better view of the fire. The left side of the pad is built out farther than necessary so I can have a cradle of logs, rack of tools, and ash bucket elevated with the stove. The outside corners of the hearth are cut back about 12" on each side to form a 45 deg. angle. This eliminates a potential tripping hazard and looks nice.

Would recommend building the pad about 5 times stronger than you believe necessary. If there is any movement at all, measured in thousandths of an inch, any grout is liable to crack. The stove will be very heavy and a couple of guys will be loading it on top of the hearth pad. That is a lot of weight moving about on top of the pad during installation of the stove. Wood used constructing the pad might also shrink a little as it dries. This could cause some cracking of grout. Would also recommend using a sanded caulk the same color as the grout around all outside edges and where the hearth meets the back wall.

Do a search for "building a hearth pad" and you will get lots of info. You might also look here for "R" values: http://www.chimneysweeponline.com/horvalue.htm

Good luck with your decision making.

John_M

 

[fossil]

Both of my stoves sit on masonry hearths 12" above the level of the floor. I like them both very much. I think they look good, and facilitate accessing the stoves. Rick

 

[DanCorcoran]

Browning BAR,

According to the Marble Institute of America, granite has an R value ranging from 0.38 to 0.83 per inch. If you want to be conservative (and your Heritage requires 1.2), then you'll need 1.2/0.38 = 3.2 inches of granite beneath the stove. If you want to take some risk, then 1.2/0.83 = 1.45 inches of granite. Granite is not a very good insulator...

 

[madison]

My opinion, the higher the better, as long as ceiling clearances are met.

Less bending over to poke and add wood, better view thru window glass from lazyboy recliner.

 

[NH_Wood]

Thanks everyone! I figured that a layer of durock and slate or tile would be sufficient for the R-value, but I haven't done the calculations. I think I like the idea of using upright 2x6's, with the extra inch or more of plywood, durock, tile. I'll do the search on hearthpad building - thanks! My ceilings are quite low (~ 7 feet), and I'll need a heat shield above the 90 elbow tying into the chimney. Thanks again! Cheers!

 

[DAKSY]

Build up your riser, cover that with 3/4" plywood to stiffen the top &
get yourself some 1/2" Micore. It has an R value of 1.1 & comes in 20 x 72" sheets for abour $20.
Put on some Hardibacker or Durarock & cover with the tile of your choice, or your 1/2" of granite.
Finsh the edges with some nicely stained wood trim & as long as you meet the specified sizes for front,
back & side clearances, you'll be plenty safe...

 

[BrowningBAR]

Browning BAR,

According to the Marble Institute of America, granite has an R value ranging from 0.38 to 0.83 per inch. If you want to be conservative (and your Heritage requires 1.2), then you'll need 1.2/0.38 = 3.2 inches of granite beneath the stove. If you want to take some risk, then 1.2/0.83 = 1.45 inches of granite. Granite is not a very good insulator...

Let's be clear, I do not own a Heritage. A Heritage is not sitting next to me... yet. To avoid the gods from yanking another stove out from under me at the last minute, let me state for the record, I am not an owner of a third stove... yet. My post was based all on theory. Like a 'What if I was building a hearth to meet the specs of a Heritage' scenario.

 

[BrowningBAR]

My ceilings are quite low (~ 7 feet)

That is a telltale sign you are an owner of an old home.