Breaking Up (a Chimney) is Hard to Do

Warning: this post contains wonky construction jargon that may not be of interest to all readers. If prone to somnolence when exposed to technical language, it is advised that precautionary cushions be placed nearby before proceeding.

Once upon a time our living room had a fireplace. It was a gas fireplace, but it looked like it had never been used. Wen moved into the house in 1992 and she said she can't ever remember her family using the fireplace. Here is what our living room looked like prior to renovation.

The rocks lend some interest to the living room because of the angled wall, their texture, and their color. Fireplaces can be nice to look at, but they tend to be huge energy wasters, even if they're not being used.

Here's where we started, and where we ended.

I took the image below with an infrared camera that I borrowed from Southern California Edison's free tool-lending library. It shows the air leakage and thermal bridging at the perimeter of the fireplace stone wall.

The R value of brick is estimated to be R0.8 per 4". So if the fireplace ranged in depth from 8" to 12", then its R value ranged from R 1.6 to R 2.4. It would be very difficult to air seal the perimeter of the fireplace, and for the flue itself it's nearly impossible to get a good air seal with the damper. All in all, a fireplace represents a huge thermal liability in a building envelope because of unavoidable thermal bridging and infiltration. If heating with wood is a priority, then a free-standing wood stove is a much more effective and efficient option.

So that's the technical energy efficiency and indoor air quality rationale for getting rid of the fireplace. But the hearth has a deep place in our psyche I think, since fire and warmth have been so important to our survival. For most of our history, the fireplace was the essential anchor of our homes, the setting around which every domestic task was oriented. Without the hearth, where is the heart of the home? Can it be a coincidence that these two words differ by only one letter?

That said, our hearth was never much of a center to our home. It's not even clear that it was ever used. Even so, the prospect of its demolition seemed a little sad. We would be destroying the physical product of a skilled mason, razing the labors of a dead man's dying trade. It felt like we were being too good for open fire, like we thought we are better than our forebears. Actually it's true: we kind of are too good for open fire, with its inefficient heat, its air pollution. And if we're not better than our forebears per se, then we are least more knowledgeable than them about the importance of a high performance home.       

And so, with mixed feelings and though the path forward seemed difficult and uncertain, we embarked on the demolition of the chimney.

Naively, I began with an actual chisel and a hammer. I didn't know what to expect or how it would be constructed inside, so I started slow.

Inside there was an oval-shaped clay liner surrounded by concrete-embedded steel reinforcing bar (rebar) surrounded by a layer of bricks.

We also began demolishing the stones on the wall surrounding the fireplace. They look like volcanic rock of some kind, and were set in what appeared to be mortar that was on the surface of the interior brick. Our neighbor let us borrow a tool called a rotary hammer that can act like a mini jack hammer to chisel out the rocks and bricks. This tool made the demolition go much faster.

P.S. Wen would like you to know that she only removed one rock for this photo opp, and that Chris did the other 4,999 rocks (and all the 10 million bricks). The rotary hammer was "too heavy and too loud," she says. "I don't want people to see this pic and think that I did half the work because you did 99.99% of it."

One of the contractors that was helping me (or vice versa) put up the structure for the vaulted ceiling (more on that soon) let me borrow his rotary hammer, and after a few days most of the bricks of the exterior were down.

The same contractor also generously let me borrow his 35-pound demolition hammer for the bigger chunks inside. Using the demolition hammer higher up was not possible because doing so would have been unwieldy and unsafe. But now that we were at ground level, I could go at it. The demolition hammer was a heavy monster and tiring to use. But it was effective. Soon there were increasingly large patches of daylight coming into our living room wall where the fireplace used to be.

All the bricks that I determined I could not re-use I schlepped wheelbarrow load by wheelbarrow load into the 30 cubic-yard dumpster. Based on the weight of each brick and an approximation of how many bricks I removed, I estimate the total mass of the bricks I removed to be something like 14,000 pounds. This unbelievable number seemed to be substantiated by a bill I later received from the dumpster company charging me for exceeding their 6-ton limit.

Eventually we got everything out and the resultant hole looked like this. The good news was that there was poured concrete below the fireplace. This meant that we would not have to excavate and pour a footing for the new concrete stem wall foundation.

Now that I had finished the demolition grunt work, I hired two skilled contractors to help me form and pour the foundation wall. You only get one chance pouring concrete and I didn't want to screw it up. We cleaned out the pit with water and compressed air so that the new concrete could bind well to the old concrete and brick. We constructed wooden forms for the new foundation wall and installed rebar.

To tie the new foundation to the old, we drilled holes about 10" deep into the sides of the existing concrete walls flanking our new one. We then cleaned the debris from the holes using compressed air and what appear to be giant pipe cleaners. This helps ensure a clean surface for the epoxy to set to. We then filled these holes with epoxy and inserted the new horizontal rebar that would go across the new section of foundation wall.

After pouring the concrete, letting it cure, then removing the forms, the new wall looked like this:

The two pieces of threaded rod sticking up out of the top of the wall I would use to tie down the sill plate (a 2x6 placed on top of the foundation wall) to the foundation, using the nuts and giant square-shaped washers at the bottom left of this image. This anchors the house to the foundation. I also removed the slate tiles and underlayment that were cantilevering out from the wood floor. After the foundation was poured, the contractors' work was done and I was in charge of framing the new wall and floor on my own.

After the sill plate is in place, the next step is to frame the rest of the floor using the existing pattern and spacing. I thought this was going to be difficult, but it turned out to be fairly intuitive. (This is notable because in general in this project tasks have tended to be much harder and more time-consuming than I expect.)

The 2x6 band (or rim) joist goes on the outer edge of the wall and on top of the sill plate. The new 2x6 floor joists are sistered to the existing ones, overlapping enough to be supported by the 4x6 girder that's spaced about 4 feet from the foundation wall, and which itself is supported by the concrete footing visible in the image above. Since the new floor joists were overlapping the old ones, I didn't need to be precise about their length, as long as they were well connected to the existing joists, were supported by the girder, and terminated perpendicular to the band joist. I air sealed the seam between the sill plate and foundation with spray foam, and the seam between the sill plate and band joist with caulk. Wen said it looked like layers of a cake. Always thinking with her stomach, that one.

Next I put in 3/4" plywood on top of the floor joists to form the subfloor, then a sole (or bottom) plate -- the 2x4 lying flat that forms the bottom of the wall.

I then spaced the studs 16" on center to support the existing half wall. In retrospect, I should have just lined up the new lower studs vertically with the existing ones above. Not doing so made the subsequent nailing of plywood, etc. unnecessarily complicated. A lesson for next time I suppose.

Wen inspects the new framed wall. It seems to have borne her scrutiny well. I believe I also air sealed the seams between the band joist and the subfloor, and the subfloor and the sole plate. I don't see them sealed here, but let's say that I did. I'm pretty sure I did.

Next on the list of things to do that I have never done before is: stuccoing the wall. I first used a pneumatic air hammer to chisel away the ragged bits of stucco around the perimeter. This was to straighten the edge and expose the existing lath wire and building paper so it could be more easily tied into the new section. I then put down two plies of 60-pound building paper, lapping the upper layers over the lower ones, like shingles. This is to drain away any water that gets behind the stucco.

On top of the building paper I put horizontal strips of "pre-furred" metal lath. This would provide a substrate for the stucco to hang onto. I don't think I did the lath quite right -- there should have been more overlap, and the piece one up from the bottom is oriented upside down -- but in the end it seemed to work well enough.

I prepped the edges of the existing stucco with glue that's supposed to help it bind to new stuff. Then I mixed the stucco powder with water in a wheelbarrow until it reached something resembling the consistency depicted in videos I'd watched and which I'd read about. Then it was time to try my hand at slathering it on.

It took four coats instead of the typical three, and lots of trial and error, but the end result is not too bad. Once it's painted it shouldn't be terribly noticeable, I hope.

I installed rafter tails and sheathing to roof the overhang where the chimney used to be. It's pretty rough looking so far, but it's structurally secure and once it's painted and cleaned up should be less offensive to the eye.

I tried matching the new shingles to the old as best I could. The old shingles are looking pretty ragged. The fiberglass mesh is showing on a lot of them, which means they're nearing the end of their useful life. But this patch should keep the elements out until it comes time to replace the entire roof.

After framing the wall, you might not have any inkling that there used to be a chimney there, except perhaps that the floor is different. Also the new studs stand out, but they will be covered up soon enough.

All in all, removing the chimney was a huge amount of work. It took me approximately 90 hours to demolish the chimney and haul the bricks to the dumpster. And the dumpster itself cost about $950, after the overage fee. There were many moments when I questioned my decision to undertake it. Before beginning the renovation, I spoke with an experienced contractor about the prospect of removing the chimney and he said, "I removed a chimney once. Never again." He advised me to leave it in place. In the end, I'm glad I did remove it, but I don't know if I would have undertaken it had I known how much work it would entail. For anyone else contemplating a DIY chimney removal, I advise you to get the right tools, have patience, and work deliberately from top to bottom.