Sheet Metal Hearth Pad?

[Patrick Harvey]

My house is a colonial antique with a fireplace in the dining room. I've been researching what it will take to install a wood stove in the fireplace. I have all the info I need regarding the liner but now I have questions regarding what my options are for a hearth pad that meets safety regulations.

In order to meet safety regulations I need to have a hearth pad that's 18" beyond the front of the wood stove. This means I need to extend the existing brick hearth with a pad that's thin. The dining room is central and people walk through it daily so I can't have a pad that is raised more than a few millimeters so people won't trip over it. I'd like to use sheet metal butted up to the brick hearth and screwed to the wood floor.

Can sheet metal be used as a hearth pad? If so, what minimum gauge can be used? Is metal considered a UL 1618 type 1 ember protector?

Here are a couple of pics of the fire place for reference:

 

[KaptJaq]

Welcome to the forums.

Do you know what stove you would like to put there? Some stoves only require ember protection, usually 20 gauge sheet metal or a single layer of tiles will do. Others require ember protection plus thermal resistance. Sheet metal or tiles over a mineral fiber board (or other thermal insulation/non-flammable material). Total thickness depends on the specific thermal resistance required. You also have to consider the clearance to combustibles (CTC) around the stove. Each stove will have different clearance numbers. If the mantel is painted wood it might be too close.

I guess what I am saying is you have to pick a stove and look at its requirements in the manual. If you give your fireplaces dimensions, size and layout of the room/house, what type stove you would consider, and your controlling factors (thin hearth, classic cast iron design, 24/7 burns, occasional fires, etc) I sure the people around here would offer some suggestions to point you in the right direction.

KaptJaq

EDIT: What type flue do you have? Tile lined? brick? what size? That fireplace looks like it may have been made for a coal burning unit. Coal units have fairly small flues and that may limit your stove choices. Has the flue been inspected or used recently?

 

[begreen]

+1 Depends on the stove.

 

[Stubborn Dutchman]

With that hardwood floor, I think one of those hearth rugs would look nice. Less likely that folks would trip over it, assuming a contrasting color. Check to make sure a rug meets system requirements of course.

 

[weatherguy]

Depending on the stove you buy they sell hearth pads that are made out of a hard material (someone help me out here), the ones Ive seen at my local shop come in different sizes, they're thin and black, if thats all the stove requires you can get by with that, they go about $60 at the shop near me.

 

[Patrick Harvey]

Do you know what stove you would like to put there?

You also have to consider the clearance to combustibles (CTC) around the stove. Each stove will have different clearance numbers. If the mantel is painted wood it might be too close.

I guess what I am saying is you have to pick a stove and look at its requirements in the manual. Give your fireplaces dimensions, size and layout of the room/house, what type stove you would consider, and your controlling factors (thin hearth, classic cast iron design, 24/7 burns, occasional fires, etc)

EDIT: What type flue do you have? Tile lined? brick? what size? That fireplace looks like it may have been made for a coal burning unit. Coal units have fairly small flues and that may limit your stove choices. Has the flue been inspected or used recently?

I'm looking at the Jøtul F 400 Castine.

I'm studying the manual right now regarding its clearance numbers. The mantel and fireplace vertical side pieces are painted wood. I'm going to have to measure tonight when I get home but I believe the mantel will clear if I get the Jøtul short leg kit but I'm not sure about the vertical fireplace surround side pieces. They need to be 19" away from the stove. I'm not sure they will clear.

The stove will be used as a supplemental source of heat. So on the coldest stretches, it will be going 24/7 but not all winter long.

As I mentioned, the room is used as a pass-through everyday since it is central to the house. The kitchen, a stairway and the living room all feed off this room. You can't see it in the picture but there is a dining room table in the center of the room. Since the room sees heavy traffic I need the thinnest hearth pad to butt up against the existing brick hearth. I don't want anyone to trip on a pad that's raised too much. 12 gauge mild steel sheet metal would be fine since it's under 3mm thick. Then I'd throw a wool ember rug over the metal plate.

The house was built in 1837 so the chimney doesn't have a flue or an ash shelf or even a damper. The chimney is just brick and goes straight up with no bends or turns, just a straight shot to the sky. It has a cap on top but that's it. I've stuffed the bottom of the chimney with fiberglass insulation just to plug it up and keep the heat from going up it. It was built as a wood burning fireplace, not for coal. The bricks were painted with black enamel paint by the previous owner. I've done a ton of research about liners and will be going with a 6" stainless flex pipe wrapped in insulation since the Castine has a 6" flue. The wood stove will T into the liner from the stove's rear flue. Badabing Badaboom.

I want to burn some WOOD!

 

[Patrick Harvey]

With that hardwood floor, I think one of those hearth rugs would look nice. Less likely that folks would trip over it, assuming a contrasting color. Check to make sure a rug meets system requirements of course.

I don't think a hearth rug would meet the requirements by itself. Also I don't think my insurance company would pay out if the house burned down because of the stove and all I had was a hearth rug to protect the floor.

 

[KaptJaq]

The house was built in 1837 so the chimney doesn't have a flue or an ash shelf or even a damper. The chimney is just brick and goes straight up

As part of your planning I would have a certified chimney sweep take a good look at it. Since it does not have a clay liner I would use an insulated stainless liner.

Taking a guesstimate it looks like you have about 40" between the side surround wood. The stove is about 25" wide. That give you about 15" to play with. I hope one of the pros will help here but if I read the manual right you might be able to make it with protected shield on the wood, rear heat shield on the stove and double wall pipe... Depends on exactly where you place the stove.

KaptJaq

 

[Patrick Harvey]

As part of your planning I would have a certified chimney sweep take a good look at it. Since it does not have a clay liner I would use an insulated stainless liner.

Taking a guesstimate it looks like you have about 40" between the side surround wood. The stove is about 25" wide. That give you about 15" to play with. I hope one of the pros will help here but if I read the manual right you might be able to make it with protected shield on the wood, rear heat shield on the stove and double wall pipe... Depends on exactly where you place the stove.

KaptJaq

Will do on having a chimney sweep give their prof. opinion. That's a good idea. Insulated liner is the way to go for sure.

I think you're spot on with your guesstimate since the opening of the fireplace is exactly 30". I'll measure tonight when I get home.

But what do you think about my idea of having 12 gauge sheet metal pad in front? Can I use sheet metal?

 

[pen]

But what do you think about my idea of having 12 gauge sheet metal pad in front? Can I use sheet metal?

If according to the specs of the stove you choose, if all you need is ember protection with no listed r-value, I suppose you could.

pen

 

[Slow1]

IF the sheet metal solution ends up being viable and you choose it, I would be very careful about how you do it in regards to the edge where it meets the brick. I'm not sure where the stove will sit etc, but if you have any sort of gap that is not filled where an ember could fall that could lead to disaster. Smooth sheet metal would seem to lend itself particularly well to an ember sliding along until it finds the edge - so if the metal just butts against the brick then a wayward ember were to fall down into the crack that is some very dry wood there in that nice old house and I bet there is plenty of air to fan an ember once it falls through... One option would be to have the metal cover the whole area where the pad is needed, not just the wood/extended area (that may be what you are planning?). Or at least overlap a row of bricks.

 

[KaptJaq]

But what do you think about my idea of having 12 gauge sheet metal pad in front? Can I use sheet metal?

The manual has two types of floor protection listed:

1. ANY NONCOMBUSTIBLE MATERIAL THAT HAS A MINIMUM R- VALUE
OF 2.0. (NO BOTTOM HEAT SHIELD REQUIRED.)
2. ANY NONCOMBUSTIBLE MATERIAL WITH THE USE OF THE STOVE’S
BOTTOM HEAT SHIELD.

ALL FORMS OF PROTECTION MUST INCLUDE A NONCOMBUSTIBLE SURFACE
EXTENDING A MINIMUM OF 16” FOR U.S. (460 MM FOR CANADA) IN
FRONT OF THE STOVE, AND 8” (200 MM) FROM THE SIDES AND BACK OF
THE STOVE (MEASURED FROM SIDE AND BACK PANELS).
THIS WILL RESULT IN A MINIMUM FLOOR PROTECTION OF 42” x 44”.

If you get the bottom heat shield, sheet metal should work. Since I do not know what is under the current brick hearth or how thick it is I would suggest the bottom heat shield in any case. 2.0 R value is pretty high. If the brick lays on wood it is no where near the required value.

One option would be to have the metal cover the whole area where the pad is needed, not just the wood/extended area

+1

KaptJaq

 

[mfglickman]

If your wood trim does not meet the specs check to see if a heat shield will reduce the clearances - Jotul can tell you. Pretty fireplace but it does look quite shallow for a stove, without some work to protect your combustibles.

 

[Eaglecraft]

Will do on having a chimney sweep give their prof. opinion. That's a good idea. Insulated liner is the way to go for sure.

I think you're spot on with your guesstimate since the opening of the fireplace is exactly 30". I'll measure tonight when I get home.

But what do you think about my idea of having 12 gauge sheet metal pad in front? Can I use sheet metal?

Patrick Harvey:

My wife and I were confronted with the same problem as you: we needed to extend the hearth but we did not want to raise the hearth extension above the grade of red oak floor because the extension would become a tripping hazard. Below I copied from a previous post replying to another poster with the same issue as you.

I would not use sheet metal as your top surface because it will be slippery as H***

Copied from pervious post:

We used a totally different approach to extend our hearth - one that I haven't seen on hearth.com. But first I might suggest that you extend your heart lastly, after the stove is installed. That way, if anything is dropped on your extension - like your stove, for instance, - nothing gets damaged.

We had the same issue that you have now. Our fireplace hearth was fine - all brick and mortar - when it was used only as a fireplace. But when we installed our Hearthstone Clydesdale in its far forward position, we needed to extend the hearth another eight inches or so. In front of the brick/mortar hearth was beautiful red oak 3/4 inch hardwood flooring, which didn't meet the requirements for ember protection or insulation. What to do??? We didn't want to create a tripping hazard by installing anything that would stand above the existing oak flooring. Whatever we did would have to be flush with the existing surface. We chose to use 1/4 steel.

We had our local steel fabricator cut a piece of 1/4 steel using his "hydro-jet" cutting table. With this machine he can cut as fancy a design as one might image - even spelling out your name in steel - if that's what you want. We chose a simple trapezoidal like piece measuring 44X40 inches. So when the door of the Clydesdale is opened, the door is completely over the steel.

Our Clydesdale has the blue/black enamel finish. So I took the steel over to the local "powder coating" service and we choose a color and texture to match the Clydesdale surface. The steel was $54 and the powder coating was about $30 (we had our 13 forced air vents powder coated at the same time so I can't determine an exact price).

I traced the steel pattern over the wood flooring that had to go and cut the wood flooring out using a Sears 3 inch circular saw. Over the existing sub-floor I placed 26 gauge sheet-metal just to use a "shim" to get the final surface perfectly level with the hardwood floor. Over the sheet metal I placed Micore 300 cut to size to get the R value of 1.1 that I needed. Then on top of the Micore 300 I placed the 1/4 inch powder-coated steel. To reiterate: Over the sub-floor I have 26 guage sheet metal, 1/2 inch Micore, and 1/4 inch steel. This assemblage is perfectly flush with the hardwood floor.

Around the steel, I inset in a piece of 2 and 1/4 inch oak (the same size as our floor) stained with "Gunstock 231" stain. I think the installation looks pretty nice. I'll add a photo to this post Saturday when my wife the photographer returns from a plant symposium.

This approach isn't for everyone, but it is a solution to making a hearth extension flush with an existing hardwood surface.

Good luck with your install.

 

[begreen]

Metal will work with the Castine. I'm thinking a 12" extension of hemmed copper would look good. You could accessorize the fireplace with a copper hod and maybe a copper laundry boiler to tie in the theme.

To capture the most heat I would put in a block off plate, preferably at the lintel level with a bit of a slope to the front. This will need an insulated liner. How tall is the chimney?

 

[Patrick Harvey]

Eaglecraft - Great idea and design for a hearth extension. I'll look into this

begreen - I love the copper idea and will prob. go this route for the material. More costly but it would flow well with our house.



So after measuring the side and top/mantel trim clearances I found that the Castine will not clear. The Jøtul F 100 Nordic QT clears perfectly so I'll be going with this stove. Not as much output but that's fine since it's better than nothing.

 

[begreen]

What do you mean it won't clear? Are you referring to the flue collar height or stove to mantel clearances? We could use some actual dimensions. There may be alternatives like a mantel shield painted white that would work.

 

[Patrick Harvey]

What do you mean it won't clear? Are you referring to the flue collar height or stove to mantel clearances? We could use some actual dimensions. There may be alternatives like a mantel shield painted white that would work.

I still haven't bought a stove yet so I'm bringing this thread back from the dead. I found a lightly used Castine on Craigslist and I would like to know what I need to do to make it work.

The stove to mantel/side frame clearance is the issue. I will need metal heat shielding on both sides and the mantle. I will get actual dimensions tomorrow.