Micore 300 and Tile

[Butch R]

Hello everyone. My name is Butch R. and I'm grateful for your help. My dilemma is I'm renovating the basement and relocating the wood stove and I'm getting conflicting information from my local Fireplace/Swimming Pool dealer and resources on the internet. To keep my clearances as close as possible to the wall, against the studded wall in my walk-out basement I have been told to double layer 1/2" thick Micore for a total of 1" fastened to metal studs. Also we took the liberty to cut 1" width off of the existing 6" studs that comprised the walk-out side of the basement to provide the 1" gap behind the Micore to meet "code, expectations" from any flammable material . I apologize in advance for not searching the data base for an answer but I was led to believe that porcelain tile will readily adhere to Micore by the people I have been dealing with. Searching the WWW I have found the opposite. The wall behind the wood stove that is being prepped and tiled measures 4' x 8' on a concrete floor. It is being prepped and tiled from the floor to the ceiling. The width of the wall exceeds the recommended width according to the powers that be.

The stove is a Warnock Hersey/Dutch West Model #2461. Clearance from back of stove is 24". Clearance from back of flue is19". It exhausts from the back. With the above improvements I've been told I can achieve 10" clearances from the wall.

My main question is will tile adhere to Micore? if not please advise. The wall behind the stove is metal studded on 13" centers both horizontally and vertically and offset both ways so I can overlap the seams on the Micore and attach to studs. I am already 1/2" raised above the surrounding sheetrock so if I have to put some hardy backer, concrete board over the micore for the tile to adhere to so be it. I thought I had this thought thru but I admit I'm a dummy.

Also I have ordered the heat shield for the stove which is supposed to be a double layer metal shield with air gap. Any advice with requirements or advice on getting tile to adhere to the wall would be appreciated. Thank you!

 

[georgepds]

While it might adhere on a horizontal surface, I wouldn't trust it on a vertical one

I'd top it off with durock or equivalent

 

[begreen]

Tile will not adhere well to micore. You are getting misinformation. For the clearance reduction there is no need for micore. The clearance reduction is established by having a non-combustible surface with a ventilated air gap behind it. This is an NFPA wall shield. It must be open at least 1" at the bottom and top to allow the free flow of air behind it. The wall shield should be made of cement board like Durock to provide a good tile base. The wall shield can be attached to the studs with any non-combustible spacer. They make ceramic spacers, but you can also make some up out of 1" pieces of 3/8" copper pipe or you can cut long, 3" wide strips of the 1/2" cement board and double them up to act as vertical spacers attached to the wood studs.

Based on the manual it looks like the minimum rear clearance with a proper wall shield is 12". However that is to the nearest combustible which will be the combustible wall and studs behind the wall shield.

 

[Butch R]

Tile will not adhere well to micore. You are getting misinformation. For the clearance reduction there is no need for micore. The clearance reduction is established by having a non-combustible surface with a ventilated air gap behind it. This is an NFPA wall shield. It must be open at least 1" at the bottom and top to allow the free flow of air behind it. The wall shield should be made of cement board like Durock to provide a good tile base. The wall shield can be attached to the studs with any non-combustible spacer. They make ceramic spacers, but you can also make some up out of 1" pieces of 3/8" copper pipe or you can cut long, 3" wide strips of the 1/2" cement board and double them up to act as vertical spacers attached to the wood studs.

Based on the manual it looks like the minimum rear clearance with a proper wall shield is 12". However that is to the nearest combustible which will be the combustible wall and studs behind the wall shield.

Thanks georgepds and begreen for your prompt reply. Forums are good because of you . begreen you confirm what I have read and for some reason or another I was told that I could do what as described above without natural convection having to occur by double layering the Micore. I am doing what the local "experts" are calling for. The space behind it as directed will be enclosed, "no moving air' so I am at a loss as to what to do. If I'm gonna be that far out the wall it doesn't matter which route I take. The carpenter I have working for me is gonna kill me if I change things up. All I want is someone to sign of on this. I had him put some 1"x1"x1/16' alum angle on the sides to mud against and the tile guy to mortar to, to keep things easy and straight. I can't remove the aluminum angle without scraping everything. Jezz, never in my life has there been rules such as these and my effort to meet them that are unquantifiable.

QUESTION? Do you think I can come close to meeting these requirements if the 2nd layer is instead of Micore is Durock? 2nd layer has not been installed.

 

[begreen]

The final layer must be something that the thinset can bond well. Cement board is good. Micore is soft. It should be fairly easy to cut an inch slot off the bottom and top. Then start and end the cement board so that it doesn't cover the slots.

 

[Butch R]

First I want to say thank you for the prompt replies. When I picked up the Micore or at least what they had on hand I was questioning myself because of it's soft and "flimsy" nature if tile would adhere to it. I still need to get some more to finish the project and when I called the larger lumber stores in my area they had actually never heard of it. So I had no one to turn to, to reinforce what I had been advised. It took some research and your confirmation to decide what to do. I will double layer the Micore and then put a single 1/2" sheet of Durock for a total of 1 1/2" for the tile to adhere to and give it some strength. I will replace the aluminum angle on the sides with a 1 1/2 webbed angle to enclose the edges to mud and grout against. As for cutting slots in the top and bottom I prefer not to and I'm not required to as per my local wood stove and fireplace dealer's advise. They are the ones that are going to sign off on this. I have insulation behind the wall and it is an exterior wall and I don't want to run the risk of getting an ember in this enclosed area. According to the R-Value chart with the combination of materials I'm using it will be equal to three layers of red brick. PLEASE if my thinking is not correct please advise. Your opinions carry a lot of weight.

I'm glad I stumbled across this site. Before next winter arrives and wood burning season starts and when installing the flue I want to install a flue fan/heat exchanger to round this project off and cross it off my list. I will search the data base for my query for a good, especially important "quiet" unit and I promise to be prepared. I don't want to waste your time and I just hate having to back track when I'm involved with something but I'm learning a lot.

After reviewing the responses I added the following.

Yes I did stumble across several sites with diagrams that show the raised wall on stand-offs that you describe. I also saw that strips could be used as long as they run vertically. Please understand I knew nothing of these requirements except for common sense. The manufacturer has the clearances listed on the back and I did what anybody else would have done and I turned to the local "experts". To say if what I'm doing is unacceptable will be a disappointment is an extreme under statement. To put up a noncombustible wall "heat shield" on 1" stand-offs is far cheaper than doing what I'm doing. Do the regulations or requirements allow for what I'm doing in your interpretation?

Once again thanks
Butch R

 

[begreen]

The proposed wall does not fit NFPA and has no tested results so it's hard to say whether it will work or not. What I think or the wood stove shop thinks is just opinion. That said, it may work fine. I just don't know how well it will work. Might be ok, but I can't say so.

 

[georgepds]

t." To put up a noncombustible wall "heat shield" on 1" stand-offs is far cheaper than doing what I'm doing. Do the regulations or requirements allow for what I'm doing in your interpretation?"

Ask the local building inspector.

Fwiiw.. the wall on 1" standoff is used everywhere. In my house the non combustible wall is brick. Back when I had a pellet stove it was sheet metal over some type of stiff 1/2" insulation. It is the free flowing air that is the insulation/protection

If you continue the way you are going I think you'll have a problem with the inspection

 

[Butch R]

Thanks begreen. I have read the testing criteria concerning this matter and they call I think the acceptable range is a 115 degree differential between ambient temps and the temps behind the protective barrier. I am frustrated because I have not used the wood stove for 7 years because I have in the past received deferring opinions about my situation from the same people. I guess I could fork over the funds to them and say hey, make it work. But I'm not in that position. I can't imagine calculating the R-Value of Micore 300 taken in to consideration which equates into 3 courses of Red Brick that it would not be acceptable. My laymans comparison is my background as a welder/fabricator but extensive experience with 12 and 90lb steam.systems and if 1/2" asbestos makes it manageable to work around surely 1" of Micore and 1/2" of durock with 3/8" porcelain tile w/compound would be acceptable. It seems there is no mandate or requirement but a suggestion which is readily acceptable. My insurance company requires none of this. I just wanted to be safe. To have to rebuild your life is one thing but to rebuild on your own error because of a fire which could have been prevented would be bad.

 

[georgepds]

Fwiiw.. the brick is the non combustible.. the air behind it is the insulation

 

[Butch R]

geogepds. Thanks, our county doesn't have any building inspections. We do not need to meet universal or other code for that matter. The surrounding counties do but we don't. Oddly enough for example the is no lagoon inspections which there are federal requirements. Also I think the sheet metal that you mention provides no R-Value and that is what my porcelain tile substitutes for. Once again my layering provides for 3 courses of Red Brick.

Once again thank you, food for thought
Butch R

 

[Butch R]

georgepds, I understand that "air" is the best insulator. My wall that this is going up against is a studded 2x6 outside wall. I would have to enclose the space inside or behind the barrier wall which means somehow I have to "sliver the sides of the studs from floor to ceiling at least 2 inches in width of the studs and sheet it with a none flammable material. I say non flammable because it will be behind my barrier and enclosed and I will not be able to monitor it if an ember were to be drawn inside. Cosmetically I would prefer not to have an air gap wall and nor I would not want to put vents on the top and bottom because of the risk of getting an ember insider. I wish you guys were my neighbors and you could come on over and discuss this and I could show you. I searched the internet for attractive stand-off wall barriers that were attractive but I have to go floor to ceiling which are not available. I even considered double layering 2-ea 1/8 plate steel sheets w/1" air gap and tacking on some ornamental iron decoration and bordering the sheets with rod and make it free standing. Let the artist come out in me. Heck I have access to a laser and water jet cutter. I will find out more this week but I refuse to invest anymore into this and I will get back to you guys. I wish I had stumbled on this site 8 days ago! You guys make perfect sense!

P.S. I already cut the studs back 1" and put up metal studs and it was a (.....). To cut them back even further might mean I will have to go trap a beaver and not feed him for a week and learn how to hold him like a chain saw and let him naw away at the studs.

Thanks Guys,
Butch R

 

[georgepds]

georgepds, I understand that "air" is the best insulator. ....
P.S. I already cut the studs back 1" and put up metal studs and it was a (.....). To cut them back even further might mean I will have to go trap a beaver and not feed him for a week and learn how to hold him like a chain saw and let him naw away at the studs.

FWIIW.. you can leave all you have done an just mount a non combustible surface 1" off the wall. It could be as thin as sheet metal, or even durock with tile on it if looks are a concern. That way you would be safe

Really, you don't want to risk a fire on the say so of some guy at the wood stove shop

 

[begreen]

Brick does have insulating value. 4" of common brick is about R=.8. Butch, if all you are looking for is peace of mind, your plan is probably ok, we just can't say how ok it will be or how much of a clearance reduction is safe. You could put a thermocouple in the cavity and see what you get at the top of the air space or at least ventilate it at the top where you could then put in a probe thermometer. It may be fine, but at this point it's just a guess.