naughted said:
I need to tap the brains of the experts. I need to build a Hearth and according to the manual it needs to be made of a UL Listed material. A pre-made hearth will not work for me so I need to build my own. I wanted to make it out of slate or tile but could not find anything that stated it was a UL Listed material. I then decided I would use brick but again nothing stating it was UL Listed except for firebrick. Anyone have any ideas how to build a compliant hearth? What materials to use, how thick it needs to be? Any help is greatly appreciated.
Ed
As mentioned earlier, the first step is to look in your manual and find where it describes the required R-value for the floor protection, along with the needed dimensions. This will vary with the stove or insert brand and model, it doesn't hurt to 'overbuild' if you think you'd ever want to put something bigger in, and I would especially consider any clearances in front of doors to be minimums that it won't hurt to exceed.
You then need to build a "sandwich" out of appropriate fireproof materials to meet or exceed that listed value. A handy "cheat sheat" on the various common materials is (broken link removed to http://www.chimneysweeponline.com/horvalue.htm) put out by one of our other Hearth.com members. It isn't mentioned, but many people consider it good practice to incorporate a layer of sheet metal into the sandwich to help dissipate any hot spots. Once you've designed your sandwich, it is a simple matter of covering it with your choice of non-flammable stone, tile, etc.
Micore is very soft, so most people that use it put it under a layer of Durock. Micore can also be hard to find and is on the expensive side.
Probably the most common approach is to use several layers of durock covered with whatever tile you like - note that you might as well ignore the value for the tile, as it really won't significantly increase anything.
It is OK to put wood molding around the outside edge as trim, so long as the dimensions INSIDE the molding meet the minimum clearances, though I'd advise going for an inch or two extra.
If you want a hearth that is flush with the surrounding floor, it is possible to cut out carpeting and subfloor as needed to make the depth for the sandwich, and this is where Micore works really well.
For a raised hearth, it is probably easier / cheaper to do the durock stack approach. If you want a really tall raised hearth, many people put a frame of steel studs down first, insulate between the studs with unfaced fiberglass, and then build the durock sandwich on top of the studs.
It is also important to check with your building inspector about what kinds of documentation and/or intermediate inspections he will want to proove that you have met the standards, also how you should document the construction so that if you ever want to replace the stove there will be a record showing what the existing hearth offers for protection. Otherwise you might have to rip it up just to show it was done right.
There are lots of threads in the forums on hearth construction, use the search engines to find them.
Gooserider
