reassurance needed

[burntoffering]

ok, this is my first post to any email group ever.

Thanks for all the great info, clearly there is a lot of experience out there so I hope you guys can help me out.
Here goes... I would like to purchase a Morso 3600 for a corner installation. My wife grew up in a house heated by wood stoves and is of the thinking that a bigger stove offers more flexibility for our heating needs. For me, all of the time spent at her dad's farm has convinced me that there is truth to this logic.

existing conditions: 2x4 wood frame, standard fiberglass insulation, 5/8" plywood exterior sheathing, 1/2" blueboard w/ plaster existing interior, 3/4" oak floors. Plan: create a raised hearth 2x6 frame, 3/4" fire-rated ply sub-floor, 1/2" durarock (cement board), 1/4" tile floor. 4' on a side from the inside corners 2' off the walls, then angled to connect those points (diamond shape hearth facing the room, if you will) for the walls 7/8" metal studs, 1/2" durarock, 1/4" tiles. same construction as the walls for the ceiling (I'll explain), same shape as the hearth just slightly smaller in overall dimensions. New brick exterior chimney, 6" round thimble connector 12" from ceiling, hence the tiled ceiling. I understand that I need 18" clearance from combustible ceiling with single wall pipe, which I did not know when I built the chimney.

If your still with me, here is my concerns: rating of the framing, durarock and tile, how hot will it get around the double wall class A thimble, what is the REAL clearances inside the exterior wall cavity, can I use mineral wool insulation for that air space, the manufacturer states that clearances from non combustibles is as little as 4"(?!), how do I make the connection from thimble to clay ( should I use a high heat cement to seal the joint, with a corner installation the dimensions of the stove leave me about +/- 6" from rear corner of the stove to the walls, etc,etc

The two floors exposed to this are roughly 680sqft each open floor plan with a cathedral ceiling in the center (great place to loose the heat I know), I'm prepared to have the area around the stove much warmer than the rear of the first floor and anticipate the cathedral will works nicely to bring the warmth to the bedrooms that are open to it above. Later I'd hope to post floor plans and pictures, but for know I'm less concerned with the warming and much more concerned with the potential for house fire. I have had a major house fire in the past, NOT due to a wood stove, but the experience has made me gun shy. ps my daughter's bedroom is directly above the location of the stove and abutting the chimney, this being the primary driver for my anxiety....

So there it is, I'm looking for help and suggestions for over-protecting against disaster. I'm a carpenter and built the house so I don't mind doing the extra work to make it right.

Thanks again,

 

[balticduck]

Hello,

Perhaps you might benefit from going down to your local bookstore - or one of the larger hardware stores/do-it yourself-type of stores like Lowes/Hoe Depot.

At these stores, there are often a selection of books that deal with specific areas of the home. One of these books will be on Fireplaces and Woodstoves.
The two primary names/publishers are Home & Gardens, or Sunset Magazine.

This type of book sells for about $18.00 .

By obtaining this book, you will find the answers to many of your basic questions.

As you will find out, some of the codes and practices have been upgraded/modified during the past decade.

With regard to clearances, ratings and safety; experience has born out the wisdom and prudence in conforming to conservative interpretation
of what is written and advised per the various codes.

If I interpreted what you've written correctly, you've already constructed the area in which you want to install the woodstove.

Ideally, you would refer to NFPA 211 Guidelines and contact your local area Authority having jurisdiction (City/County Building & Safety)
prior to construction. Based upon what you wrote, it seems like you're trying to install a type of Hearth-Stove.[Maybe, I am wrong?]

Regardless, from my 27 years of experience as a Chimney Sweep I've found that people tend to overlook the importance and value of
having the proper amount of airspace between materials, thus allowing for proper air flow & reduction of fire hazards.

The objective should be to install the stove/appliance safely - rather than trying to get it as close to the walls as you can.

Pragmatically, you will benefit more from the radiant heat by having the stove away from the walls.

Now, if your wall has already been built - and there isn't the proper airspace between the materials (masonry wall/materials), then a
viable option would be to install a type of "heat-shield" panels [usually made out of metal]. With these panels placed a minimum of one inch
from the wall (allowing the airspace for air flow), you will be able to have the stove located closer to the walls than the traditional clearance.

One other aspect needs to be considered - and it is often overlooked; the clearance that is needed - in the front of the stove.

Frequently, the amount of clearance space needed at the front of the woodstove is not realized - until after construction has been completed.

For most situations, the "minimum clearance" ---key word --"starts" at 16 inches. That means you need to have at least 16 inches of clearance/ non-flammable/fire-resistant materials.

With a wood flooring, you would want to protect your home from having any possible fire hazards - such as sparks, embers escaping the firebox
and igniting/charring the flooring. (This includes any carpeting nearby.)

Equally important is the clearance/space needed to adequately load the wood into the stove.

So.........one of the simplest ways of answering your question(s) - is to buy one of the books that already has a number of the answers
printed in it.

------Final thought: Seems that it would make sense to have the entire base of the raised foundation for the stove to be made extremely well.
Considering the amount of weight of the unit - and the desired effect of increased radiant heat, it might be prudent to consider having the
majority of the raised foundation constructed out of masonry, rather than just being framed.

Hope it works out. And, remember to use a humidifier on the stove......

 

[begreen]

Welcome, this should be a nice setup. Is this the model 3610? If so, it needs an R=.8 hearth. A single layer of 1/2" durock is only R .26 and is not enough. You'll need at least 3 layers of durock + tile to squeak close to R.8.

I'd recommend you lay this out on the floor ahead of time. Use masking tape and a cardboard template for the stove. The hearth may need to be a bit longer than 48" on the sides.

 

[burntoffering]

Thanks for your replies. Yes it is the model 3610. For the hearth I could frame off the floor with 2x4 (to keep the height modest) then fire rated 3/4" ply, then 3 or 4 layers of durarock. Is there a better rated material? Also, just in front of the raised hearth, for ~ 10", I plan to resess tile into the floor so I have some additional spark protection.

 

[begreen]

Ah, with the tile extension in the floor, you would probably be ok. Technically, it's not quite kosher. The stove radiates frontward and requires the hearth to be at the stated R value all the way out 18" in front of the glass. But you are going to be close with just the hearth and the tile extension will work.

Is the brick chimney already built? If not, can I talk you out of this? An exterior chimney is not going to perform as well as an interior one. If you can possibly go straight up, that will give you the best results. For stove location what you want to do is to drop a plumb line from ceiling to where you think the stove's flue centerline will be. If you have the stove already, that would be even better for getting exact measurement for the ceiling support box location. If the chimney is already in, then can it be insulated or placed in an insulated chase?

(broken link removed to http://www.woodheat.org/chimneys/chimneys.htm)
(broken link removed to http://www.woodheat.org/chimneys/evilchim.htm)

 

[jeffman3]

When I built our raised hearth I did like you are planning. I framed using 2x4 and a plywood base. Then I layered Du-rock to meet the "R" factor for the stove, and finished with ceramic tile. Just make sure you have met or exceeded the "R" factor requirements for your stove, and allow for at least the min. clearances before you build. I built mine to exceed the min. requirements all the way through the project. Do the research thoroughly before you start, and make sure it is what you need and want before you start, you absolutely don't want to have to do it twice.