Rebuilding a Fireplace Surround

This Instructable (Instructanovel) details the process I went through to demolish an existing fireplace surround made of flagstone and replace it with a much more attractive (at least to my eye) custom built one.

When I moved into my house, one of the things I definitely wanted to change was the fireplace.  Every time I looked at it - massive.... brooding.... flag-stoney - I couldn't help but hear the theme to the "Brady Bunch" start up in my head.  Sure as death and taxes, every time I'd walk into the room, I'd hear "Here's the story ..... of a lovely lady..... etc, etc" - aaaaand I had to make it stop.

So after several months of looking at it (and hearing that insipid song) I decided to tear the fireplace out.  After all, what better way to incentivise yourself to start a project than to make it look about a hundred times worse than it already does, right?

I'm going to cover the demolition only to give a few pointers and maybe give some insight into what you may find should you have a similarly constructed fireplace.  I'll then cover the construction of a new fireplace that's a lot more to my liking - and a lot less dominant in the room.

Realize that much of what I'm doing here can be adapted to fireplaces of different construction.  Even all-brick fireplaces can be given a face-lift - just maybe not as extensive as this one.  Sometimes all it takes to get your own "vision" is to see how someone else did it (hence, Instructables!).

Total Cost on this project is roughly $600 - but that's solely based on what I had on hand (leftover quarter-sawn White Oak from another project), what I found (the granite) and the materials I chose to use (spendy countertop concrete).  Your costs could be more or less depending on how big your installation is, what materials you want to use, etc.

While nothing in this instructable is terribly complex, it does require some construction and woodworking skills to pull off.  Tools (or a well-equipped relative) are always a big plus as well.

As with all home renovations involving sledgehammers, you should ask someone smarter than you if you're not sure it's OK to wail on a particular wall.   Make sure to use appropriate safety gear and also make sure you're not violating some obscure building code.  Either that, or just don't tell anyone what you're doing and hope you don't do something you can't recover from.  I choose option #2.

OK, OK - for all the Hall Monitors out there - I'm KIDDING.  Be responsible, smart, safe, and considerate - contrary to popular belief, the world was not made by Fisher Price.

Step 1: Tear Down the Wall - Er - Fireplace

So, first things first:  get rid of the old fireplace.  Sounds pretty easy, doesn't it?  To be honest I wasn't 100% sure what I'd find behind the stone, but given that I was familiar with the construction behind the fireplace wall and knew I was dealing with a gas fireplace (free-floating metal insert), I figured that it was basically just a veneer of stone about 2" thick (I also climbed into the attic to look at the surrounding structural and confirm that I wasn't going to do something I REALLY regretted). 

I pussyfooted around with a 2lb sledge for a little while  and finally realized I needed a much bigger hammer, and that  I'd also need to find a different way of transmitting the blow of the hammer to the stone (other than metal-on-stone) if I didn't want to haul 1000 lbs of crushed flagstone out of the house and end up finding random stone chips scattered around the place for the next 6 months.

I switched to a 10-lb sledge hammer and an 18" length of scrap 2x4 occasionally augmented by a pry bar and masonry chisel.  I used the 2x4 mostly like a chisel by placing the end against the edge of a stone, and striking the other end with the sledge - so the blows / impact forces were generally parallel to the wall, not perpendicular, which may have been harder on the underlying structural.  It usually took a few blows to get the stone loose, at which time I'd either just work it completely loose with my hands or with the help of a pry bar.  The 2x4  does a fine job of transmitting the force without shattering the stones.  I think I used two boards in total (they will eventually split and fall apart).  By being a little careful removing the stones, I was able to re-use them in my yard.

Be systematic and careful in your demolition - use only as much force as you need, and don't get in a rush - in a few years, is anyone going to care if it took you a few additional days to finish?  Probably not.  I remind myself of this often.  I used plenty of sheet plastic to control dust and chips, and cleaned up after each major phase of removal which makes working in the area a lot safer and more pleasant.  Doing your cleanup as you go also prevents you from having to monkey 1500 lbs of stone and mortar out of your living room at one time, and reduces the bits of stone, grit, and dirt you'll track into other parts of the house - possibly damaging floors, feet, relationships,etc.

Once the demolition is complete and the area is cleaned out, this would be a *perfect* time to replace your 1970's era gas fireplace with something more efficient - if that was something you wanted to do.  I was OK with the one that was in place because: 1) I don't use a fireplace but maybe a half-dozen times a year, and 2) even though the house was built in 1978, my particular fireplace had apparently *never* been used.   After 30+ years, the flue and firebox still had their original paper stickers inside.  No kidding.  The only "fire-like" marking I could find looked as though the previous owner's juvenile delinquents had burned a Barbie Doll in effigy, but that's just a guess.

Step 2: Installing the Fascia

This is one of those rare moments when just asking paid off.  The management of the building I used to work in was having some renovations done to the lobby - a lobby clad in sexy black granite.  One night on my way home, I asked some of the workmen if I could have a few pieces of what they were prying off the walls and they were kind enough to give me some of the broken granite panels - none of which were long enough by themselves for what I needed, but I thought I'd figure something out.   After a little sketching/thinking, I realized that I could still build a fascia with the pieces if I abandoned the idea of having one-piece sides.  I did some test-layouts and found that I could get what I needed by putting square pieces in the corners.  A local stone fabrication shop charged me $250 to cut and polish the stone - which seemed a bit expensive - but they did a better job than I could have - so whatcha' gonna do? (only the inner opening is polished BTW).

I attached the stone to the firebox and wall with Henkel PL Premium Polyurethane Construction Adhesive starting with the bottom pieces and working my way up, bracing pieces as I went, and allowing 24 hours cure-time between tiers.  Polyurethane Construction Adhesive is super strong and temperature resistant - and bonds very well to just about everything.  Attaching to the firebox isn't a problem because this part of the firebox never exceeds the service temperature of the adhesive (on this model fireplace) and the stone provides a decent heat-sink - but you need to make sure that whatever technique you use it will stand up to the heat and expansion conditions that it will be exposed to. 

Step 3: Casting the Hearth and Mantle

I decided to pour a concrete hearth and mantle because I wanted something substantial and fireproof, and I figured it was a perfect way to get used to working with concrete before I jumped into a much larger project like pouring my kitchen counters.  The finished concrete is hard to tell from the black granite - a happy accident - probably due to the use of crushed marble as an aggregate in the concrete.

I won't be providing a detailed set of plans - mostly because I don't have any plans (just some post-it notes and a napkin or two) and partly because your situation is going to drive your design decisions. However,  I am attaching a full-scale Sketchup model of my design to this instructable for anyone interested in that kind of thing.  You can download Google Sketchup for free here: http://sketchup.google.com/ (if you don't already have it), and take measurements right off of the model in Sketchup if you simply must know. 

One nice thing about working out designs in Sketchup - especially when working with concrete - is that it will automatically calculate slab volumes for you ..... which is very handy when ordering $60 bags of fancy-pants concrete.

With the explosion in popularity of concrete as a building product to be used inside the house, there is a plethora of useful information available on how to construct molds, what concrete mixtures to use, etc - so I'm going to do a bit of "glossing over" and just hit the high points of molding/pouring small slabs like these - be sure to follow recommendations of any products you buy, and ask a lot of questions of the manufacturer or their reps:

1) I used 3/4" white melamine particle board as my main mold material, with blocks of construction-grade wood as supports.  Screw everything together - don't use glue.  Your molds need to be very strong, they need to hold water, and you need to be able to take them apart.

2) Black silicone sealant was used to seal the molds and give a nice, even rounded edge to the final pieces. I laid out the seams with blue tape, swiped in the silicone, and immediately removed the tape leaving a nice consistent edge.  Black is used because it stands out against the white where clear or white would disappear.

3) Tape over your screw heads or fill them with modeling clay because you'll need to remove the screws when you de-mold your castings and concrete does an amazingly good job of filling in screw heads making them extremely difficult to extract.

4) I used "Buddy Rhodes Bone White Counter Mix" and tinted it with Black Ultra-Fine Dry Pigment.  I followed all of the recommended safety and mixing instructions / ratios.  I used a beefy corded drill with a paddle mixer in a 40-gallon Rubbermaid trash can - which was *just* big enough for this job.  It might be worth renting a mixer or at least a mortar mixer for anything bigger.  A word on the pigments:  wear clothes you don't like - you'll be amazed at how the stuff gets everywhere and it does NOT come out.

5) Enlist the help of a (beefy) friend - preferrably two - when it comes to mixing and filling your molds - I really don't think it can be done by one person efficiently - even with two people you'll be rushing.

6) I used a common metal lathing as my "reinforcement".  It probably wasn't necessary given the way the hearth and mantle are fully supported, but it was cheap insurance.

7)  For grinding the surface, I used a Makita PW5001C Water-Cooled Grinder and diamond pads ranging from 50 to 1500 grit.  I found a great deal on eBay on the grinder - only to find when it arrived that the water-supply hose wasn't included - and Makita wanted an arm, leg, and first born for one.  A quick trip to a local industrial hose and fitting supply house yeilded a sweet custom-built water supply hose with a quick connector and garden hose adapter for the outrageous price of $18!  Craziness!  Who says customer service is dead? (Thanks to Hose & Rubber Supply, SLC, Utah).

8) Warning: Grinding the concrete is MESSY.  Think of a mud-sprinkler, and you'll get the general idea.  It would be ideal to do your grinding outside in a place you could easily hose down, but if you're forced to do it inside your shop or garage you'll want to /cover everything within 10 feet or so with plastic.

9) Voids in the concrete (if you have them) can be filled with a mixture of epoxy, pigment, and concrete dust but I prefer tinted Magic Sculp, or Apoxy Sculp (Epoxy sculpting putties). 

10) The final finish I used is a high-gloss catalyzed urethane coating normally used on floors.  I picked it up at a local industrial coatings retailer for about $55 for a gallon (including catalyst).  There are a number of coatings that could be used, but most require some form of maintenance, and ... well... I'm not that motivated.  Spraying is the recommended application technique, but in the case of the slabs I just poured it on and evened it out with a cheap foam roller.  Watch for runs and don't overwork the material.  Two fairly heavy coats and a week of cure-time in a hot garage gave a tough-as-nails finish.

11) Warning: At the risk of stating the obvious: concrete is heavy.  Hulk heavy.  About 150 lbs/68 Kg per cubic foot heavy.  When it's "green" it's also pretty fragile - like a really fat baby - so be careful as you'll be working with something that's both heavy AND breakable.   For the first several days it's easy to damage it with rough handling - like letting it drop onto a work surface or dropping tools on it.  When setting up molds, make sure that whatever you're planning on setting your molds on - tables, sawhorses, crates, midgets - is up to the task.   When de-molding, get help when moving your castings if you're not 100% sure you can do it yourself.  The mantle I cast weighted around 85 lbs, and the hearth 255 lbs.  Even though I could maneuver the hearth unassisted, there was no way I was going to try to delicately place it in it's final position without the help of a friend. 

Tip:  A little trick we used to set the hearth in place on a finished floor without damaging the floor, hearth, or us, was to lay a few 1/2" wooden dowels on the floor to use as rollers and roll the hearth into position.  It's tricky to remove the dowels, but it makes moving the slab SO much easier and safer. 

Step 4: Building the Surround (Pillars) and Mantle Support

This design has a number of influences - a mixture of Asian, Arts & Crafts, and Contemporary elements.  While the surrounds (pillars) and mantle support *appear* massive, they are built using "veneered box" construction making them light, strong, and relatively inexpensive to build.  I had a nice piece of quarter-sawn White Oak (a leftover from another project) and realized that I could re-saw it into 1/4" "veneers" and bond the veneers to a structural carcass made from more common materials - in this case, scraps of hardwood, 3/4" Baltic Birch plywood, and 1/4" Tempered Hardboard (or Tempered Masonite). One 8' x 7" x 8/4 (2") Oak board was re-sawn into enough 1/4" veneer to cover all the parts.

Here's the basic process:

1) Determine the curve of your pillars and make a template - be sure to leave a short flat area at the top and the bottom of the profile to make attaching trim a lot less painful.  I usually push a thin board against two finishing nails or clamps and then trace it's length to determine my curve (see illustration).  Clean up your template with a file.  Trace your pattern onto your stock pieces and then carefully cut the curves in the side panels using a band saw or saber saw.  While it is not critical that the cut curves are super-smooth (saw marks are OK) - they do need to be even, ripple free, and identical to their matching piece for that particular pillar - so a little work with a rasp or SureForm might be in order. Don't throw your cut-offs away, they will be very helpful when gluing your veneers on the curved faces.

2) Once you have determined how wide you want your final pillars to be and how thick you want your mantle support, subtract the combined thicknesses of the veneers and side carcass pieces to get the dimension of the filler-blocks you need.  For the pillars these filler blocks can truly be "scrap" pieces as they will function solely as spacers between the sides.  A little more care is called for on the mantle support as the blocks in the ends will have bolts running through them anchoring the mantle support to the pillars - so they need to be flush with the ends of the carcass pieces.  Make sure that when you place any of these blocks, you aren't shooting yourself in the foot by placing them where they will be interfering with some planned feature - like assembly bolts or anything like that. 

3) Assemble the pillar sides and mantle support sides using glue and screws.  The critical thing here is that the profiles stay aligned with each other.

4) Cut pieces of tempered hardboard the same width as that of your box assemblies, and the length of the curve.  The easiest way to measure what length you need for the curve is to use a flexible ruler or if you don't have one, mark a thin strip of wood, or tape a piece of masking tape along the curve length and cut it where it meets the flat part of the pillars -  then measure this tape and you'll have your length (or just use it as a "story stick").  You'll probably want to do this for each assembly separately just to compensate for any variance in construction.  Glue and fasten the hardboard to the edges of the pillar and mantle support assemblies.  Fill in at the top and bottom of the profile with small strips of hardboard to completely fill in the front of the assemblies.

5) Once again, measure the length of the curve.  Take a piece of veneer stock that is long enough to cover the entire front end of your assembly - including the flats.  Carefully measure your curve again and cut your veneer stock about 3" longer than you need,  then measure and cut your "curve" piece from the center of this board.  This will give you two small strips to fill in the "flats" at the ends of the pillar face and you'll have a continuous grain pattern all the way up the front of the pillar.  At this point you WANT a tiny bit of overhang on either side of the face because you'll be sanding it flush to the sides once the glue cures.  Make sure the cut edges at the top and bottom of the curve are square.  Use the cutoffs (the ones I told you to keep) from the carcass sides as clamping cauls to hold the veneer in place as the glue cures.  Once cured, bevel the edges of the "filler strips" at the top and bottom to match the angle where they meet the curved strip, then cut them to length and clamp/glue them in place.  Carefully sand the veneer flush to the sides - being extra careful not to round or bevel the edges.

6) I glued the side veneers on one side at a time.  You don't need to pre-cut the curves for the side pieces - you'll do that after bonding each side using a band saw or saber saw.   In *theory* you could glue up both sides at the same time, but then you'd pretty much be forced to cut your curves solely with a router and flush-trim bit - which is risky because you'll be taking off a lot of material - some of it against the grain - and it's easy to "blow out" your edges even if you're reverse-routing.  I chose to glue up one side at a time, rough-trimming my curves on the band saw between glue-ups.  This made flush trimming the edges on my router table a lot less stressful because I was removing less material and could easily see what I was doing.  Once the flush-trimming was done, I spent a little time using a belt sander to get rid of any visible edges or seams.  If everything goes well, the seam between the side veneers and the face veneers will be all but invisible.  When you put a bevel on this corner (later), it hides the seam even more effectively - making your pillars look like one solid piece of wood.

7) Cut some stock for the faux pins - I used Cocobolo, but any contrasting wood will work.  Lay out and drill holes for their positions using a forstner bit, or sharp twist bit - a spade bit is NOT what I'd use as it will make a mess unless it is very sharp - and I've never seen a really sharp spade bit.  Use a sharp chisel to square up your holes.  These holes should be slightly smaller than your faux pin stock as you're going to taper the pins and drive them in for a friction/glue fit (I epoxied mine from the back side).

8) Put a 45 degree bevel on the front edges of the pillars with a router or, preferably, a router table. Don't bevel the edge all the way down - leave an inch at the bottom that is NOT beveled so that when you put the trim on, you'll have a nice sharp corner to fit it up against.

9) If you notice in the pictures, one of the sides of the pillar is shorter than the other - specifically, the "inside" of both pillars had to be cut back by the same thickness as the stone fascia - go ahead and do that.

10) Cut and install the "foot" trim around the base of the pillars.  I used 1/4" thick by 1" Cocobolo with a 3/16" bevel, and epoxy to attach it.  Cocobolo is oily wood, so you'll want to strip as much of the surface oil out of it as possible before gluing it up.  I use laquer thinner or acetone as a wash before I glue Cocobolo (let it evaporate, of course).

11) Attend to all the details - mostly sanding at this point - but cleaning up any glue squeeze-out, a little filing here and there - getting rid of anything that will mess up the finishing process.

Step 5: Dry Assembly and Fitting

You'll want to dry-assemble the pillars to the mantle support.   I drilled the holes in the mantle support filler blocks (the holes where the bolts will go) first.  Then, I clamped everything together making sure it was all flush and square - then using a twist bit - used the holes in the blocks to transfer the hole positions to the pillars - then unclamped it all and drilled the holes in the pillars.

Bolt your parts together and dry-fit them to your wall/hearth - make sure it's all going to fit the way you want it to.  I used carriage bolts because getting a wrench into the gap in the mantle support would be a PITA.  Once you're happy with it, go ahead and take it all apart again - it's time for finish.

Finishing:

I decided to just go with blonde wood - no stain - because it provides a better contrast to the hearth and mantle.  I used the same kind of catalyzed urethane (clear) on the wood that I did on the hearth and mantle, but used a satin finish instead of gloss - and I sprayed it instead of using the caveman "splash and spread" technique I used on the hearth.

One mistake I made here was that I sprayed the finish too thick - i.e. too little solvent - and I got an "orange peel" finish on the first coat.  I was annoyed, but thought, "Oh well, I'll just sand it off and try again."  I got the Naptha and some 320 grit Aluminum Oxide paper and went at it.  After about 10 minutes of sanding, I wiped away the Naptha - only to find that I'd barely scratched it.  I ended up using up an entire sanding belt (for my belt sander) on each piece(!)  That's some tough finish.  So, learn from my mistakes - when you're shooting this stuff, do a test shoot on a spare board and check that the finish lays down.

I used 2 fairly heavy coats of finish - this is where you'll see the grain of your woodwork come to life.  Quarter-sawn Oak is also called "Tiger Oak" and you can see how the ray-flecking looks like tiger stripes - it's beautiful stuff.   I hate sanding and prep work, but when you're shooting the finish, it makes it all worth it (well, almost all, anyway ;)

Step 6: Final Installation

Go ahead and bolt your assembly together snug, but not too tight.  Fit it to the wall and hearth, and when you're happy with the alignment, go ahead and snug up your bolts.  I used a little bit of Blue Loctite along with a fender washer and a lock washer - which was probably overkill - but that's just how I roll.  No spontaneous dissasembly allowed.

I used polyurethane adhesive to attach the pillar assembly to the stone fascia.  You don't need a lot of adhesive - just a few strategic spots here and there.  Your main concern is that the pillar and mantle support don't fall away from the wall - so there's no need to run continuous beads of adhesive or anything like that.  Be careful where you place the adhesive as well - think about squeeze out and quickly clean up any that does.  Let the adhesive cure before installing the mantle.

After the adhesive is cured, test place your mantle and mark the bottom with painter's tape so you can quickly align it again.  A few blobs of adhesive should do the trick gluing it to the fascia and mantle support and pillars - once again, don't go crazy with the adhesive.

This is optional, but when it's all in place, you can seal the junction at the floor, the back of the hearth, and the underside of the mantle with black silicone to keep dirt out and give a more finished look.  Use the "tape technique" that's used when making the molds to ensure that you get a nice, clean, even bead of material.

Enjoy your new fireplace :)

Sorry if this turned into an "Instructanovel" - lol.  I hope you got some good ideas from it - or at least were somewhat entertained.  Thanks for taking the time to hammer your way through it. 

Now go outside and make some dust ;)