Thursday, June 30, 2011

Betts Fireplace and Chimney Project, Day 17

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Installation of 7th and 8th flue liners.  This will top the chimney out at about 3' or so above the ridge of the dwelling.  Mason Alejandro is preparing for tomorrow's work.

Builder Trey Perkins and wife Deana showing the scale of the Betts fireplace.

View of masonry from interior of lodge's great room — Tennessee field stone will be applied to this masonry body.

The first fire in a new fireplace is always exciting and affirming no matter how many times you've done it.  Dickey lit the christening fire here, and I really enjoy how the fire light illuminates the basket weave brick pattern of the firebox.  This fire was started without priming the flue, and despite this, and the 5' tall opening, no smoke entered the space of the lodge.  The saying, "It'll jerk the cat off the floor," comes to mind.

Family visit to site.

Wednesday, June 29, 2011

Betts Fireplace and Chimney Project, Day 16

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Deer during my morning coffee walk.

Roof scaffolding constructed in order to finish chimney.  This is the sort of added effort involved with building a chimney after framing, or within an already existing building.  It's much more practical to build the chimney prior to framing (when possible), and given the structural capacity of our systems, the chimney can double as bearing point within the super structure.

Installation of 5th and 6th flue liners.

Tuesday, June 28, 2011

Betts Fireplace and Chimney Project, Day 15

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 Installation of 3rd and 4th flue liners.

This is an interesting shot demonstrating the skill of a good laborer.  Without assistance, Passo, who is down on the ground, has hoisted up a 5 gallon bucket of mortar ( 40 pounds or so) to the scaffold.  He has landed the material safely on the scaffold, and while every thing is still in motion, is about to deftly unhook the bucket with a lariat like twitch of the rope.  I've seen him do the work of two men consistently.

Surrounding masonry being developed around flue liners.

Monday, June 27, 2011

Friday, June 24, 2011

Betts Fireplace and Chimney Project, Day 13

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View of smoke chamber closing to throat from inside the firebox.  This is prior to parging which will smooth out and eliminate the rough surfaces within the smoke chamber.

Deflecting edge of clay brick liner that protects the permanent structure of the fireplace openings inside 8" wall face.

 View of general progress from interior of lodge's great room.

 Reverse corbeling of chimney base at exterior of lodge.

Smoke chamber has reached flue size.  18" flue, at right of image, ready to be set in place.  No fire brick will be used beyond this point.

Thursday, June 23, 2011

Betts Fireplace and Chimney Project, Day 12

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Raising the outer masonry in conjunction with the smoke chamber.  This void will be filled with concrete and steel.

Filling the cavity between smoke chamber and outer masonry.

Smoke chamber as it is corbeled in to reach flue size.

Wednesday, June 22, 2011

Betts Fireplace and Chimney Project, Day 11

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Infilling clay brick to transition curvature of firebox to the smoke chamber above.

Parging (plastering with fireclay) the rough edges of the smoke chamber to ensure air flow. 

Monday, June 13, 2011

Betts Fireplace and Chimney Project, Day 10

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Clay firebrick liner completed and firebrick corbeled out to face of clay brick (not visible within this shot).  Chimney base underway opposite side.  Note the 20' x 30' tarp providing shade to the work area — in addition to providing a better working environment, the shade allows the mortar to cure at a normal rate.  The intensity of the South Georgia summer sun would draw the moister out from the mortar too quick, and compromise the integrity of the masonry.

One of several Gopher Tortoises residing in the woods and fields of the Betts property.  This one is still wearing the dust of it's burrowing.  These are quite interesting animals. They play an important part in the ecology of the Southern wilderness, though their numbers have dwindled a great deal due to a plethora of environmental hazards.  They burrow extensively, and the mounds created by the tunneling of the Gopher Tortoise are distinctly visible when a healthy population is present.  These burrows provide shelter for a number of other animals such as foxes, bobcats, rabbits and snakes, and a noticeable decline of these partnering animals occurs when the tortoise is absent.

Gopher Tortoise down in it's burrow to escape the mid day sun.

Sunday, June 12, 2011

Betts Fireplace and Chimney Project, Day 9

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Second and third courses over arch — cut brick develop the airfoil shape along the inside surface of the fireplace opening.

Wood vaults are structurally completed.  Firebrick course over arch ties in with the firebrick surround.

 Firebrick course over arch completes the structure of the arch.

View of firebox interior from above after completion of structural arch.

Firebrick surround is leveled over the arch into a complete coursing.

Saturday, June 11, 2011

Betts Fireplace and Chimney Project, Day 8

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Because the outside walls of the wood box's barrel vaults are not buttressed, the immediate space above the barrels will be reinforced with concrete and steel.  This will eliminate outward thrust and convert all the individual elements of the vault into a solid unit able to withstand both compression and tension. 

At this stage, concrete has been poured over the barrel of the arch and pieces of #4 rebar have been fitted to the radius of the barrel and placed on 4" centers within the concrete.

Concrete is then poured again, and pieces of #4 rebar have been placed laterally on 4" centers within the concrete.  A grid was later established by placing rebars in the opposite direction.

On the other side of the fireplace, the second barrel vault form has been set in place and is ready to receive masonry.

Second barrel vault completed.

Friday, June 10, 2011

Betts Fireplace and Chimney Project, Day 7

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Oval firebox being developed.
Initial arch spanning fireplace opening completed.

Barrel vault of left wood box completed.

Thursday, June 9, 2011

Betts Fireplace and Chimney Project, Day 6

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10 courses of the firebox 'basket weave' liner laid.  Note how the front edges of the firebox radius protrude past the 8" faces of the fireplace opening.  This will deflect extreme heat away from the fireplace's permanent masonry elements.

Why the clay brick liner?

The purpose of the clay brick liner is an aesthetic one that is especially appropriate for traditional architecture.  Fire brick are precisely shaped units that tend to be void of variation, color and, to a degree, personality.  Technically, code doesn't require firebrick , but my inclination has always been to include it to provide a sense of security to myself and clients.  

But in the case of a rusticated hunting lodge, I prefer the clay brick for several reasons.  It provides a more natural, and earthy backdrop suitable to the fire it contains, as opposed to fire brick which can appear somewhat 'industrial' and look a bit cold to the touch.  The precise geometry and featureless uniformity of firebrick also seems to be mismatched with the blackening of the firebox — an inevitable result of creosote build up that comes from wood burning.   

Wednesday, June 8, 2011

Betts Fireplace and Chimney Project, Day 5

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While camped on site I've had the habit of taking morning walks before work begins.  This is a fireplace ruin I found in the woods of the Betts property, and I thought it would make an interesting post.  Generator problems have put a dent in the day's progress.

The lighter colored brick at the base of the chimney are original to the initial foundation of this fireplace.  The red brick reveal that this fireplace and chimney was rebuilt some where along the way.  Brick from this era were fired at low temperatures with wood burning kilns that left the brick somewhat soft to the focused heat of a fireplace; especially when this was the only source of heat during the winter, and it was kept burning.  Spalling brick at the foundation level show greater decay due to extended proximity to the firebox.

Fox tracks during my walk.

Sunday, June 5, 2011

Betts Fireplace and Chimney Project, Day 4

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The liner is not bonded within the structural masonry elements of the fireplace.  This is to say that, should the fire box begin to decay,  it can be removed and replaced without damaging the integrity of the system over and over again for hundreds of years.  But this is one of many approaches to building fireplaces.  Formal fireplaces may call for split firebrick laid on a herringbone pattern within the firebox.  There are a range of options, but I have a particular fondness for building with the oval, clay brick, basket weave.   

Saturday, June 4, 2011

Day 3

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Templates for the clay brick firebox liner are cut and numbered.  Patterns are made from fire brick units that are consistently shaped and easily identifiable during production.  Later, the fire brick templates will be used to scribe clay brick which will compose the finished surface of the firebox liner.   Liner bricks are cut on parallel angels to maintain the correct narrowness of head joint through the entire bed depth of the brick.  This will prolong the life of the clay brick liner by preventing head joints from opening up and causing accelerated attrition.

Friday, June 3, 2011

Betts Fireplace and Chimney Design, Day 2

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Defining the scale and final footprint of the firebox.  Later in the day the outer fire brick walls of the firebox were raised to about a foot.  The oval shape deserves a fairly detailed explantation which will be given in the near future.  Mr. Betts requested a fireplace opening that was roughly 40" to 48" wide, and tall.  We opted for the 40" width, but chose a 60" height because a standing rectangular shape so effectively frames the character of the fire which is notably vertical in nature; this as opposed to the more typical fireplace opening which is shorter than it is wide, and sometimes hides the tops of flames consequently robbing the fire of some of it's glory.  Additionally, the taller the opening, the more opportunity for radiant heat to be reflected into the hosting room.  The challenge however, is that the taller the opening, the greater the opportunity for smoke to enter the interior space, so the dynamics of fireplace mechanics must be comfortably grasped before attempting such a system.  When designing a fireplace, my goal is to bring a 'whole fire' sensibility to the interior of a dwelling — a fire you can stand close to, and experience in it's entirety with the same fondness and enchantment held for a campfire. 

Thursday, June 2, 2011

Betts Fireplace and Chimney Project, Day 1

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Raised block foundation for the fireplace and chimney being double capped with two layers of solid 4" block.

Firebrick inlay within the second course of solid 4" concrete block.

Wednesday, June 1, 2011

Researching the Fireplaces of 'The Grove Park Inn'

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As this relates to many of the decisions being made with the Bett's Hunting Lodge fireplace design, I've written an account below of my experience studying the fireplaces of the Grove Park Inn back in 2001.  I've been meaning to document this occasion for some time and am glad to do so now with purpose.  

The question of whether one kind of fireplace produces heat more efficiently than another is secondary to a much more important question —"does it draw properly?  Or, in other words, does it 'smoke' into the building?" This is a real challenge when it comes to constructing large fireplaces because the proportions of a proven standard sized fireplace do not simply correlate up.  Five times the 'fire' isn't merely five times the combustion energy — exponential things are happening.  

When a 'grand fireplace' fails,  more than likely it has been built according to the proportions of a normally scaled fireplace, and when you consider that a good half of the 'regular' fireplaces out there are not working as well as they should, it's easy to see how matters can get out of hand quickly when it comes to building on a massive scale.  Building scenarios are complicated further by the fact that the success or failure of a system cannot truly be determined until the chimney is completed at which point there is not much recourse.

A good case example of this proportion/correlation issue can be observed in the lobby of the Grove Park Inn of Asheville, North Carolina.  The historic Grove Park was completed in 1913, and was not simply raised with indigenous stone, but clad in hand picked, uncut boulders no doubt.  Twin grand fireplaces straddle the vast lobby.  The fireplaces are 10' wide, 7' tall and 7' deep.  Each of the 10' wide openings are spanned with a single massive natural stone. 

So with all this attention being focused on such an important structure at such an important time, you would think all the kinks would have been worked out with the mechanics of the actual fireplace systems to be built right?  What's more, is our tendency to assign an almost supernatural reverence to the knowledge and skill of the pre-powertool tradesman which I think in large part is indeed deserved.  But, nevertheless, the ball was dropped in a big way when some poor soul way back when was asked if he could build one of the largest fireplaces on the planet and he responded, " sure, no problem.  I've built many fireplaces; my father built fireplaces; my father's father built fireplaces ...."Get the picture?

As you walk into the Grove Park lobby, the fireplace to the right has been abandoned as a 'working fireplace,' and serves only as an interesting centerpiece.  On the other end of the lobby is a matching fireplace that some years back was 'revamped,' as well as it could be, to perform successfully as a functioning fireplace.  Sometime after, a fire broke through the system internally where it had been made vulnerable during the restructuring, and set a portion of the six story resort ablaze.  This was later repaired further, and the giant fireplace is still used today as a glorious whole log burner.  

The scale of these fireplaces and their proximity to one another makes the Grove Park a very unusual boon of a case study.  One must simply walk in, without even ducking, flashlight in hand, and commit a craning glance to discern the difference between the two. This one doesn't work — it looks like this; this one does — it looks like that.

In 2002, I made an appointment with the Grove Park's engineer, who was second or third generation engineer to the Inn, as I recall.  I drove up for the day from Atlanta, and combed through the fireplaces with great attention, besetting my patient host with probably too many questions.  We even went out on the roof of the hotel where I was able to take a catwalk over to one of the massive chimneys, and peer in for close inspection.  One of the most valuable R&D field trips of my career. 

All this to say, you can't be too cautious when it comes to building one of these giants. After my trip to the Grove Park Inn, I went back to work on the Pierce/Lee project where fireplace construction was edging into the schedule.  At this time I began defining parameters that guided me to the unique style of fireplace I still build today : 

— 1st rule of thumb : the cross section area of the flue must be 10 - 12% of the area of the fireplace opening.  One must go to great pains to insure this. 

— Understanding that fire, and all of the combustion elements involved with fire, behave circularly in an upward spiral is critical.  Where ever curvilinear elements could be implemented into the design in a positive way I did so.  I found three significant opportunities for this : 

1. The terra-cotta flue liners may be specified as cylindrical.   
2. Corners may be eliminated in the firebox — this led to designing the basket weave, oval firebox which is a signature element of some of our fireplaces still today. 
3. Lastly, and very importantly, an 'air foil' may be shaped at the top of the fireplace opening where brick are normally just corbeled inward like the underside of a staircase.   Here spanning brick can be roughly cut in such a way as to form a curved throat.  Later, this area can be plastered (parged) with fireclay into a smooth transitioning air foil.  The air foil prevents turbulence as air is drawn into the firebox across the top of the fireplace opening by the vacuum of hot air rising through the chimney.  As this air is pulled into the top of the firebox, it meets the rising combustion elements of the fire itself, and the two separate influences remain laminar mixing slowly together only after rising well within the chimney chase.

Additionally, I've always believed that fireplaces and chimneys should be structurally sound beyond question providing fail safe support to the super structure in general.  International Code only requires 8" of masonry surrounding the firebox, and merely a 4"veneer of masonry surrounding the flue tile of the chimney.  

Our specifications for masonry mass within a fireplace system far exceed the provisions of International Code.  According to code, where the fireplace and chimney come into contact with the structural framing, holding to the 8" minimum masonry mass requires an airspace of 2" between the masonry and the framing.  This can be difficult to maintain because masonry debris tends to fall into the void during construction, and this obviously creates contact.  12" of masonry allows the framing to abut to the masonry and 16" of masonry allows 4" of bearing on top of the masonry while being safely abutted with the 12" minimum of masonry between.

As for the 4" minimum of masonry surrounding the flue tile and composing the shape of the chimney, this is simply not structural.  Structural masonry is defined as 8" or more of masonry constructed in such a way as to have load bearing capacity.  When constructing chimneys, we build with an 8" minimum wall thickness.  Stream lining the bones of a structure to a bare minimum is fine for the bottom line, but the magic of artful building occurs in it's mass.  And it's no coincidence that this also provides substantially where posterity is concerned which, aside from being quite 'green,' is the responsible thing to do for future generations.  As I've said many times before, the chimney is a wonderful and often wasted opportunity to make an incredible architectural statement.   

These are the basics of how we build fireplaces and chimneys.  We are always grateful to Jim Buckley of 'Buckley Rumford Fireplaces' for playing such a big role in helping us develop a fireplace building philosophy that has consistently delivered staggering aesthetic and functional results.

I'm aware that I never quite got around to actually describing the critical flaw of the original Grove Park grand fireplace design.  I can't do all the work for you — visit Asheville — with a flash light.  It's a great city.  Try 'Salsas' for fine Caribbean cuisine.