insert installation hearth questions

[rwhite]

New to the board but I have searched and didn' find the answer I was looking for. I am going to install an insert into my masonary fireplace. My concerns are with the hearth clearances. I have attached some pics below of the fireplace. This is what I know for sure:
The fire box and 4" out on the hearth are masonary. What is under the tile from there out I am unsure and have no way that I know to tell without cutting into something. The hearth is 18" wide and flush with the hardwood floor in front of it. The stoves that I am looking at extend any where from 4-6" out onto the hearth. This leaves any where from 12-14" of non combustable material. Most of the stoves require 18". Although some of the literature is confusing as they state the hearth must be at least 18" from fire box to edge and later say that it must have 18" from insert to edge. Any how enough rambling. My question is do fiberglass hearth rugs or stove boards qualify as non-combustible material if there is hardwood floors underneath? If not what is the easiest way to extend the hearth? I was thinking that I could build a hearth extension that slid into the fire box and extended out enough to meet the requirements. This would just sit on the floor and be removeable so I wouldn't have to cut into the floor. I would make it about 2" thick so it would also raise the stove insert 2". I have the room inside the fireplace to do this as my opening is about 30" tall.

Here are the stoves I am considering so your thoughts on those would be helpful:
Osburn (I think) 1600 used built in 1990
Avalon 996 extended (not sure what the extended means) 1992 model
Timberwolf new
Pacific Energy Vista
Drolet

 

[Dix]

Welcome to the forums !!

Is the floor of the actual fireplace flush with the floor, or is it higher?

**ETA* I just reread.. the FP floor is flush?

 

[rwhite]

The fireplace floor, hearth and hardwood floor are all on the same level.

 

[Dix]

What are the measurements of the FP inside?

And how big is the house, layout, etc?

 

[rwhite]

Here are the specs.:
37"W tapering back to about 28" wide at the rear.
30" tall at the front the rear kind of slopes forward in the back
It is 23" deep at the bottom. Due to the sloping of the back it is 22" deep at 16" tall and about 15" deep at the top.

The house is about 2200 sqft. It is 3 story with a basement that all but 2' is under ground. The main floor is about 800-900 sqft as is the basement. There is 1 large room on the top floor that is about 3-400 sqft. I planned putting the stove on the main floor. It won't be the only source of heat as I also have a gas furnace. Main purpose of the stove is to heat the main floor and hopefully drift some heat upstairs. Not real worried about the base ment as it stays a fairly constant temp even without heat.

 

[Dix]

Can you put a free standing stove somewhere else?

If I had my druthers, it would have been a free stander.

 

[begreen]

Fiberglass rugs may give some degree of personal comfort, but they are not qualified hearth extensions. A stoveboard may work, but it depends on the requirements documented by the insert maker. If the hearth requirements are ember protection, no problem. If they are R = 1 or higher, you will need better protection.

 

[btuser]

I think your idea of building up the hearth is your best bet. My stove is 16" from the edge of the hardwood floor because I pulled it out instead of mounting flush. Ive got a hearth rug but it still bugs me. I'm looking for a piece of granite I can use as an extender but hopefully I don't find it yet. I've got too many other projects rolling.

 

[rwhite]

So i dug a piece of grout out and there is at least 2" of sometype of mortar substrate under the tile. What is the best material to build a hearth extension from? I was thinking plywood covered by micore then hardiboard then tiled. My main worry is where the plywood will butt up to the insert. What do you do about that edge and getting the thermal protection?