Although electric under-floor heat in the bathrooms uses a fair bit of energy (9 watts per heated square foot), it is a little luxury that we can choose to use or not to warm our feet in the cool of our winters.

We bought the Flextherm heating system kit, which includes the appropriate length of green-covered heating cable for the size of the room, as well as round guides for the wire. The thermostat is purchased separately. I chose to donate the guides to the Habitat For Humanity Restore (whence cometh many of our building materials).

The Flexsnap system

Instead, I purchased the Flexsnap 12″ gridded squares to clip the wire into. It is easier, will raise the level of the tile equal to the 3/4″ fir flooring that meets it at the doorway, and at $2 each, for a small room, I thought I could justify the expense. Another advantage is that they stabilize the floor so that a second layer of plywood is not necessary before tiling. Some internet research suggested that one could just hot-glue the wires in place, forget about the guides or gridded squares. I’m very glad I didn’t try cheaping out on that step. It would have been constricting, and I would fret over whether I was damaging the wires.

The orange Flexsnap blocks are quick to install directly onto the plywood sub-floor with screws.

The heating cable clips into the tiles, 3 or 4 inches apart. It starts near the thermostat.

After installing, the wire needs to be checked with an ohmmeter (or multimeter) to make sure it is conducting electricity/verifying the resistance/not broken.

I’ve spent far too many hours cutting the white 1″ square tiles out of the all-white 12″ blocks of tiles and replacing them with brown ones. 88 x 25 = 2200!

The "renovated" bathroom tiles.

I hot-glued them into place, but found when it came time to install them, many of the brown tiles fell out of the blocks. Just made more work. I learned that only good-quality large glue sticks work, not the little craft sticks.

All the voids in the Flexsnap tiles have to be filled with the flat part of the trowel before the notched trowel is used to raise the mortar to accept the ceramic tiles. The 88 square feet of floor used up four 50-lb bags of polymer-modified mortar.

Raff came to help, mixing the polymer-modified mortar in the wheelbarrow for me, so I could steadily apply the tiles on top of the Flextherm  heating wires. This made the job go much more smoothly.

The bathroom floor

Insulation is arguably the most important energy-saving component of our green home. We experience strong winds here almost constantly, and have incorporated several heating systems, as it turns out. In theory, we would only need to use the centrally-located thermal mass fireplace for heat, as long as the house is well-insulated.

The idea of R-Value as a measurement of insulative ability of an insulation is quite misleading. We might choose to use R40 fibreglass batt in our ceilings, but because it is impossible to prevent spaces or compression of batts once they are installed, wind and air can make their way into the heated space in hundreds of places.

The soy-based, closed-cell, 2-pound spray foam insulation fills every possible space to prevent air leaks. 3.5″ of foam is rated R28. Effectively, it is much better as an insulator than R40 batt. It costs about 4 times as much as regular batt insulation (average of $5/sq. ft. in our case) but the cost will be recovered in a short time in energy savings. (I will do more research and provide specifics and a few links later.)

Action Spray Foam came over from Surrey to spray our house. The compound they use is heated iso-cyanate, which is nasty stuff in its liquid form. It smells like the inside of a dirty rubber hose times ten. The sprayers use full gas filter masks and risk burns and hair removal on areas not covered by protective clothing. The rest of us work outside or in the RV.

Spraying produces lots of inert waste pellets (labelled “popcorn”). Currently, Action takes them to the landfill.

The foam that spills over the stud edges needs to be cut away with saws or scrapers so that drywall can be applied without bulging.

spray foam in the crawl space

insulation in the basement bedroom

(….pause while I chase a mouse)

One of my tasks when I arrived back on site, after vacuuming out all the wall cavities, was documenting the “house guts” before they get covered up by insulation and drywall. Alice arrived on her bike to help (well, she arrived to observe the studio concrete-forming process, but as Raff so astutely observed, visitors are quickly pressed into service.)

Basement hallway

The process involves laying two tape measures along the walls at right angles to show where all the wiring/plumbing/heating elements are located before we cover them up with insulation and drywall.

insulation in basement hallway

This is one-fifth of the old wooden garage door I got on Craigslist for $90. It’s pretty ugly, but I think I can turn it into a silk purse.

That's not smoke above the door - we just haven't cleaned it yet.

And the ugly smoking door is no more. We have a silk purse of a functioning fire. D put gaskets along the top of the door, in spite of Lakeshore Design’s advice to the contrary. We also got a draft going in the side chimney with a burning newspaper before lighting. We didn’t remove the chimney cap. It’s a miracle!

The progress on the house is not all that apparent this week. It’s not showy. Rather, it’s the systems we’re working on, which will all be concealed behind drywall and other finishes.

red and white water

The plumbing: No, it’s not just Canadian flag-waving here. The water pipes need to show that there are two completely different systems: the red for the collected rainwater to flush toilets, and the white for potable water to the rest of the house.

Neil adds another duct to the montage

The heating and Heat Recovery Ventilation (HRV): It’s a complex system, with the attic ductwork needing insulation, and great and small ducting pipes trying to hide in closets, walls, ceilings, floor joists, crawl space. The crew has been working for 3 weeks on this. The irony: it’s supposed to be a back-up heating system (heat pump and air handler). The goal is to have the thermal mass fireplace (TMF) provide the majority of heat in the cold weather.

smoke gets out where it's not wanted

(At this point, the aforementioned TMF is a dirty word in our house. On our first small firing, it smoked mightily, from around the door. I’m quite sure it’s been installed according to all the instructions, but clearly the air inflow or outflow is not functioning the way it should. In theory, the smoke exits at the bottom of the unit, through an 8” masonry chimney pipe from the side of the burning chamber. Kerry, the fellow who sold the kit to us (Lakeshore Design in Ontario) assures us that we don’t need any braid gasket around the door, and that it’s “easy” to straighten out the door. He’s not a very good listener, nor does he know how to provide good customer service. He just repeats the info in the installation guide and talks over us. He says we need to take off the chimney cap that our stonemason took half a day to install. I don’t believe the chimney cap is restricting any airflow at all.)

the "offending"? chimney cap

Electricity: John and helpers have also been here for nearly 3 weeks. The various systems are rather interdependent, needing wiring for the fan or hot water heater, or space around plumbing pipes for the ductwork, for example. John estimates 4000 feet of wire. We’re trying to think ahead to end use and comfort. Lots of lighting for older eyes, plugs on the living room floor for table lamps, pot lights where we might need them. It’s hard to know how the house will be used sometimes, so we just have to make our best guesses. One interesting new item in the BC Electrical Code is a garage plug-in for an electric car!

back-framing

Back-framing: Now that the systems are getting close to done, Ron’s crew can finish the framing around ductwork and plumbing, dropping the ceiling or boxing in smaller spaces. I have also been asking for nooks and crannies and lowered ceilings and bookshelves and grab bars and towel racks, etc. The “tin-whackers,” as Ron calls the heating guys, asked for the workshop wall to be insulated and drywalled so that they could finish the big duct on that wall. I asked for plywood as a finish, so that D can screw all manner of storage solutions anywhere he wants, without having to find studs behind. I’ll also use that approach for the kitchen wall, where cupboards and tiles will hide the plywood.

insulated shop wall

So, I leave the house for 10 days. I will have withdrawal symptoms, I’m sure, but I’m getting a bit of cabin-fever, and I could use the break. Ron and the boys will look after it just fine for us. I’m grateful that I could be on site for so many of these critical decisions.

Russell’s just finishing up the fireplace. I’m very pleased with the results. We won’t be able to burn in it for a couple more weeks.

I have occasionally heard the adage “Progress can be measured by the scraps on the floor/ground.” These are some of the messy scraps left over from the fireplace. Now that we’re nearing the finish line, I’m looking forward to reclaiming the space. I won’t miss the mess. I won’t miss the screech of the masonry saw.

(D’s contribution. The following article is pretty detailed, for anyone considering using a masonry mass heater. Guest appearance by Liam if you read all the way to the end.)

Thermal mass fireplace kit installed

With masonry heaters the mass isn’t just with the masonry: really, they’re a mass of contradictions, too.  In a world that’s moving to high-tech heating technology masonry heaters work on decidedly old technology.  Where convenience is becoming more and more the hallmark of modern life, masonry heaters involve a little good old fashioned work and elbow grease.  It seems anomalous, but true, that burning wood can offer an environmentally better way of heating your home, and where the energy for most people’s domestic heating travels a long distance, the energy for mass heaters is extremely local.

The concepts behind masonry heaters are not new: apparently in Roman times it was not all that unusual for smoke and combustion gases to be vented beneath floors and beds, thereby warming the rooms.  In Europe they are known as Russian or Finnish fireplaces, although they are typically designed as room-heaters, not whole-house heaters.

As Gail has described, a masonry heater, basically, is a high-tech fireplace.  What distinguishes it from the familiar fireplace, however, is

-            the air and smoke channels are carefully planned and more complicated;

-            the design requires at least 1800 lbs. (800 kg.) of bricks/rocks/masonry around the burn chamber;

-            the unit requires an air tight, closed door, much hotter burn;

-            the heater burns only intermittently, not continuously, even when intended to heat continuously;

-            location/siting.

Taking some of these features in order: probably the most important aspect is the channelling of the gases involved in the combustion.  The design makes this substantially more complicated or convoluted.  That’s why you purchase one as a kit and don’t build it from scratch; the kit includes all the pre-designed smoke channels. The incoming air is carefully controlled so that only enough for combustion is allowed (excess air will simply cool the burn and create smoke and soot) and for some the burn is top-down.  You prepare the fire, in other words, by loading the kindling on top.

The real difference in venting concerns the exhaust gases, which are, first, directed around inside the firebox so that there is a kind of double-burn.  Instead of having the initial gases from combustion going up a chimney, they are circulated around the burn chamber for a secondary burn.  After that the (heated, of course) exhaust gases are directed into channels throughout the masonry mass before heading up the chimney.

The mass is also part of the equation; you need at least 800 kg. to do the job which, in simple terms, is to absorb a lot of energy very quickly from a very hot fire and then release it very slowly into the home.  The rate of absorption/release is, of course, affected by the quantity of mass; the less the mass, the quicker the total masonry absorbs the energy and begins to release it.  Manufacturers suggest, for example, that cottages might be better suited to mass heaters with facings that are thinner , so that the heat release can begin more quickly.  For a conventional home you might want a mass that is thicker, typically 4”-5”.  The mass can take any form; it obviously includes the actual burn chamber, but also the surrounding masonry facing.  Interestingly, the burn chamber is separate and distinct from the facing, so much so that they cannot be connected by, for example, brick ties.  There must be space/joint between them that allows for expansion and contraction of the burn chamber.

Heater kit covered with 1/4" cardboard for expansion, before adding 4" facing rocks. Note chimney on the side.

With a burn chamber smaller than most fireplaces, the burn is much hotter than a typical fireplace.  The burn chamber is enclosed, generally using a close-fitted door and venting air (via a damper) from outside the home.  The damper can be used to create a slower, longer lasting fire for the occasional traditional fireplace feel.  The exceptionally hot burn means that the fuel is used more efficiently than with most wood-burning heaters, as this report confirms.  One of the collateral advantages to masonry heaters is that you can incorporate ovens into them, as these gallery photos show.  We’re incorporating one into our unit, and we’re really looking to using it for, obviously, baking, but also slow cooking in general.

The heater is not burned continuously.  This is almost counter-intuitive, but if you think about it it makes sense.  The idea is to create, say, two intense ‘burns’ per day; one in the morning and one in the evening.  With each burn the surrounding masonry is quickly re-heated, then, for 8-10 hours, slowly releases the heat into the home.  Continuous burning can actually damage the refractory lining, as this study and report indicates.

Where you locate the heater in the home is key.  The idea is to encourage as much free air circulation around the heater as possible.  For that reason the heater should be in a central location, and never part of an outside wall.  You can see this, and how various heaters look, in the gallery photos, above, from the Stovemaster site.  Clearance of at least 5” from adjacent walls or structures is best.

Masonry heaters, properly used, are more efficient than good woodstoves.  This is the conclusion of Omni Test Labs, a Portland, OR testing facility.  Their reports are online and, while technical, are certainly readable.  They show that emissions from masonry heaters are remarkably low.

To check out various manufacturers and vendors, go to The Masonry Heater Virtual Mall. For Canadian manufacturers or distributors, you could try Lakeshore Design or StoveMaster Expect to pay in the neighbourhood of $3000 plus shipping (it cost us $417 to have the kit shipped from Ontario to Vancouver).  We ordered a second door ($900) for a see-through effect.

So: all of this is talking through our hats, as we haven’t tried the heater and oven yet, but we’re really looking forward to it.  Gail has found a source of mill scraps very close to our home, so we can probably get a continuous supply of fuel there.  It all means being a little more involved in heating your home, whether it’s collecting mill scraps or taking the chainsaw down to the beach.  Either way, it will almost certainly give us the satisfaction that always comes with doing something yourself.  As my father used to say when he press-ganged me and my siblings into loading firewood: “You get warmed twice – once when you cut, load, and split the wood, and once when you burn it”.

Liam cuts firewood

Remarkable! A miracle! The thermal mass fireplace kit from Lakeshore Design in Ontario has finally arrived. About 7 weeks late, but…

It was delivered with the all the stone for the house – 26,000 lbs. in total in 19 heavy pallets.

Finally something to post about. It’s been slow. More to come soon.

After some debate about the design of the chimney in the absence of our fireplace kit, Russell is working on the main floor chimney, which has to go through the roof so the roofers can fit flashing around it. He’s using the Craigslist bricks I got some time ago (with Tess and Nancy’s help – one very heavy load in Grandpa’s truck.)

We've decided to leave the brick exposed in the loft

Russell's bricks rise up through the roof