Monday, January 18, 2010

Fireplace design


We've had a slow evolution in our overall fireplace wall design (and even the model of fireplace we selected) from the beginning of our home project up to now. Initially, the main guidance I gave my brother is that I really liked some pictures I had seen of fireplaces with an exposed flue (see this old post), and Molly and I both thought this would be great to incorporate into our design. With that initial guidance, the first look we got of a potential fireplace wall design was in a rendering my brother did of the family room:

This was an awesome first stab at it, though in hindsight what you see above could never have worked. The main reason is that you can't have a fireplace enclosure that is so close to the fireplace unit (i.e. tight fitting) because there are clearance requirements to prevent dangerously hot air temperatures from occurring above the fireplace. You need larger enclosure clearances than what is shown in the rendering.

Also, from a design standpoint, what we really wanted was a double-sided fireplace (see-through) so that the fireplace could be enjoyed from the other side of the wall in the library. Though I'm a big wood fireplace guy, after researching fireplaces and talking to fireplace vendors, having a double-sided wood-burning fireplace wouldn't be feasible because it would actually suck out more heat from the room than it would add to it. For a wood-burning fireplace to be efficient, it really needs the brick behind the fire to store heat and radiate it into the room (as is the case in a single-side fireplace). Take that away and what you get is just a vertical airstream sucking heat out of the room, up, and out of the house.

So, we eventually decided to switch to incorporating a double-sided gas fireplace. Molly was definitely all for this because she loves the convenience of just flipping a switch to turn on the fire, and I was glad that it would be less messy (with no wood to store), simpler, and would mean that the fireplace would be used more often.

In the construction prints, my brother modified the fireplace wall design to have a ledge on either side of the fireplace:

Also, the flue was vented vertically all the way up through the roof of the house.

The vertical vent was necessary because we had chosen a "natural vent," or B-vent gas fireplace. This still intakes air from the room and vents it to the outside of the house, but gas flames can radiate more heat into the room and are more efficient than wood-burning fires. The vertical vent was not ideal because we had to run the flue through the master wardrobe upstairs. Another option is called "direct vent" for gas fireplaces, where the flue is actually two tubes that are co-axial and serve as the air intake (from the outside) and air exhaust (to the outside). These are the highest efficiency fireplaces available because they do not take any air from the room. Another bonus is that they do not have to be vented vertically, allowing a horizontal vent in certain situations (which would save us space in the master wardrobe).

So we eventually changed to a direct-vent gas fireplace model, with a horizontal vent to the South side of the house through the first-floor ceiling. We decided to nix the fake logs-type gas fireplace design and go with something a little more contemporary and truth-in-design oriented. After all, if it was going to be a gas fireplace, it might as well not pretend to be a wood-burning fireplace. Eventually we settled on this model fireplace:

This is basically a "fire-ribbon" design, where the gas burners are in a thin line across the fireplace, and can be surrounded by ceramic stones (which also act to store and radiate heat). There are a few companies that sell a "fire-ribbon" gas fireplace (Spark, Napoleon, and Montigo) and I found Montigo to be by far the cheapest. We selected the Montigo LF38-ST fireplace. If you click on the link and look to the lower right, you can see a video of what it looks like in operation.

For some reason, almost all direct-vent fireplaces have the flue opening off-center, and I really wanted the flue to look on-center coming from the top of the fireplace. So using my CAD program and talking to our fireplace dealer, we worked out an acceptable solution to route the flue back on-center that is still within the manufacturer's guidelines:

Also shown above are the minimum clearances necessary to meet the manufacturer's installation guidelines. The exposed flue has to be sheathed in another metal tube for safety reasons, which you can also see in the above designs.

Lastly, after going around and around about how to finish the exterior of the fireplace, I found a very cool tip on a design site where an architect actually created a fireplace surround with concrete backer board (typically used for tile underlayment), stained with concrete stain and sealed. His cost: $20. A pic of his finished look is below:

I like the porous concrete look, in contrast to the painted drywall that would be behind the fireplace. So, with this finishing in mind I started designing how this would look for our fireplace, and in the process also happened on the idea that the ledges on either side of the fireplace would be perfect for storage space and could also double as extra seating areas if we had custom cushions made. My designs are below:

Again, the storage areas would have a custom cushion made to fit on top so that you wouldn't actually see the doors or hinges. Add a couple throw pillows and you get two perfect reading nooks (or as Molly said, two perfect time-out corners -- kind of cushy time-out corners if you ask me).

On the library side it would look like this:

The colors you see are tentative, but it's the direction we're headed for now. This is all still a work in progress, we'll see how the final product works out!


John Curran said...

I agree, truth-in-design is the way to go. I also like the honest-material use of the concrete backing board. Fascinating to follow the evolution of the fireplace. I notice there is nothing resembling a mantel... the entire point of the fireplace being the fire itself, then?

Brendan Koop said...

No I think we definitely could have a mantel on the library side, we just haven't reached that point yet. Once we move in we can figure out whether we should put a shelf above the fireplace or actually put a real mantel in (or just leave it without either).

Evan said...

I'm not a big fan of the "truth-in-design" philosophy--seems like a code-word for minimalism. After all, your house will be a farmhouse inspired design, but it's not a farmhouse at all. Come to think of it, we could probably do without shingles or siding with all our advanced materials these days. Why not just live in a big concrete cube, for consistency's sake?

Your Unabashedly Nostalgic Uber-traditionalist Brother

John Curran said...

Yes, Evan, exactly! But nicely stained and sealed, of course.

I'm not afraid of minimalism, and I love 'surfaces.' That said, I recall an episode of 'Absolutely Fabulous' where a gift of red wine so upset the delicate balance of a minimalist apartment that order was restored only when the bottle was set outside the door!

With the 'not-a-farmhouse' thought, perhaps a beam from an antique barn would make a great 'mantle'/shelf over the fireplace on the library side.

Brendan Koop said...


Thanks for your comment, even if it is the poster child for a straw man argument! :-)

Truth in design has nothing to do with minimalism. Our house certainly wouldn't fit any architecture critic's definition of minimalism (in reality, true minimalists would hate our house -- too much vernacular form and maybe a touch too sentimental). Truth in design: all it means is that if you see a structural beam, it's there because it's actually doing something; it's supporting the house and bearing a load. That enhances the "reading" of the house so much more, you know that what you are looking at is there because it really needs to be there and isn't fake. I like truth and authenticity in architecture just as much as faith ;-)

Truth in design also has nothing to do with ornamentation. Anyone can go ahead and have lots of ornamentation if they wish, just make it out of authentic materials (i.e. not faux painted marble). This also means you should be able to afford it, it's not cheap (one reason we don't have lots of ornamentation, we'd rather spend our money elsewhere). If one can't afford real marble, use wood and let it look like wood. Let the materials you use look like what they are. All those columns and ornamentation in ancient Greece? Classic truth in design (no pun intended). Those are made out of solid stone, and they actually support the buildings. It took mammoth acts of human engineering to make those structures, adding to their wonder (we know they are real).

As far as the "farmhouse" thing, our house isn't a farmhouse, there's really nothing about it that says "this is a real farmhouse." The window wall should be enough to convince anyone of that. Instead, one would rightly say that it is inspired by the local vernacular forms of barns and real farmhouses that dot the Minnesota landscape, and thus from a design standpoint intentionally fits within this context while still clearly being of the current times. This is what anyone should want: don't throw away the past, but reference it and use it in current designs instead of radically departing from it for novelty's sake (e.g. much of modern architecture). A veritable architectural hermeneutic of continuity.


The end.

Evan said...

As a good younger brother, I really just wanted to get you riled up. Mission accomplished! Seriously, though, I love the house.