Non-combustible hearth - I aks you this...

[Ashful]

We've all seen the "non-combustible" hearth requirements of some stoves, often spelled as, "masonry on dirt, with no wood framing anywhere below."

Okay, seems simple enough. In fact I've seen a few state things like, "the way a real fireplace is made." Okay...

My old kitchen fireplace is pretty typical of what you'll find in any 240 year old house around the mid-Atlantic region. The construction of these fireplaces should be held in the highest regard... after all someone had a 24/7 fire going in these for at least 100 years, and likely much longer, without ever having burned the house down.

Now, anyone who's spent any short time around old houses surely knows that the heavy lintels on these fireplaces were typically wood, and most have seen the wood doors mounted to wood casings that surround the openings of these stoves. No surprise...



What may surprise those who aren't familiar with old houses is that the floor/hearth of many of these fireplaces is actually supported by wood timber. In the case of mine, here's a photo of the basement / fireplace foundation:



Note that thing which looks like a fireplace, which it may have actually been prior to 1770. It's currently the foundation to my kitchen fireplace, directly above. Distance from the floor of my hearth down to those timbers is 26", and I find it difficult to imagine the heat radiating off the bottom of any wood stove is going to approach that of having fires built directly on the open hearth.

So, we have a stone hearth, consisting of 26" of stone, rubble, mud, horse hair, and even some straw, all set atop a wooden frame. Used as the primary place for cooking and much heat, for who even knows how many years since 1770, and no sign of any fire damage. So, I aks you this... what's with the "non-combustible" hearth requirements for some of the lesser expensive stoves? By these requirements, I would not be permitted to install one of those stoves in a fireplace that was used for open burning for probably 200 years longer than the life of the guy who wrote the requirements.

 

[Ram 1500 with an axe...]

I love the stone work you have, do you have any history on the people that used to live there back in the day? Post all the pics you want of your house, it is very interesting.....

 

[Ashful]

Thanks. Yes, I know every owner since 1773. In fact, it was just one family until 1921, and the daughter of the last generation of that family to grow up in this house visited us here, just a few months ago. I know a lot about that family, as there's a good bit written about them, and have had some limited correspondence with some of the other families who've lived here since.

I've posted so many pics here, I suspect most folks are getting tired of seeing them!

 

[BrowningBAR]

My big fireplace has the same thing. There is wood laid in between the stone and throughout the interior of the fireplace.

 

[begreen]

All hearths are not created equal. How are the stove mfgs supposed to know what the stove will be installed in given all the variables of construction over the ages. Your home appears to have been built for an affluent owner. They appear to have been generous with materials. But for every big home built there were thousands that were smaller, many not so finely built. There were lots of homes that caught fire back in the old days. Those examples don't remain because they burnt down. The worst cases are often more modern retrofits done to cow barns, stables, carriage houses and the like, by contractors that made hearths more for show than practical use. My wife grew up in a stunning chestnut inn with big stone hearths set on timbers. One very cold winter we nearly burnt the place down with a 24/7 fire in the upper hearth.

 

[bholler]

We see quite a few old fireplaces like yours and yes they were used for a long time. But they also burnt lots of houses down to. Our house at one point had bare pipe running up through the floors to a chimney built on a wood platform on the attic floor. Those pipe had little to no clearance just because it used to be done that way doesn't mean it is ok.

 

[webby3650]

I'll take a crack at it.
It all comes down to money! Stove manufacturers spend tons of money to get a stove tested and approved for sale to the open market. Often, stoves that are only approved for a solid masonry hearth are old designs or low end stoves.(typically, but not always)
The manufacturer would have to retest in order to approve it for ember protection only. This is a huge expense and the rate of return must be high enough to justify the cost.
On the "low end" stoves, it would drive the cost up, and again, it has to be worth it to the manufacturer.
It could also be that some companies don't find it worth the risk, since we've become a sue happy society.