One thing that sets my teeth on edge as an energy auditor is when folks assume that a new home won’t have energy problems or be inefficient. A friend recently mentioned that weatherization and efficiency work must have a great market with Maine’s old housing stock but would be pointless in new homes. *Commence ripping out hair.*
The reality is that 99.99% of all homes can be substantially improved for efficiency and savings. And this absolutely, 100%, includes houses built in the last 5 or 10 years. New means a great many things, but energy efficient is not necessarily one of them. Like an auditor friend says, “A house built to code is the worst house you’re legally allowed to build.”
The worst house I ever audited
This leads us to the blue ribbon example — the worst house I ever audited — which was built in … wait for it … 2008. (OK, maybe I already blew the surprise.)
Buildings from every era of construction have issues. Many problems, like minimum insulation levels, are ironed out by the building code. But some construction flaws are not yet addressed by building code; these often stem from a poor combination of building type and construction technique. And if we’re real lucky it all happens in one building at the same time.
The house was a 2008 ranch built into a hillside. It had an attached garage with a centrally located chimney. The garage was on the basement level with a driveway sculpted into the hill slope. The master bedroom was over the garage, where the chimney was framed in between the garage and main house.
An open-concept kitchen was just off a cathedral ceiling great room that occupied a large chunk of the floor plan. The house had a lovely view with the surrounding hills, framed with autumnal foliage. The front of the house faced south, providing lovely evening sun. You could see why someone would buy it.
So what’s the problem?
So, why did the homeowners call me? First, there were tremendous comfort and heating issues. Many of the rooms were cold, even though the heating bills were through the roof. The house had a clean north-south orientation, meaning good sun on the south. But the north-facing rooms were uniformly and brutally cold.
The basement was standard: modern slab and wall construction with formed concrete. It was a thoroughly modern installation with capillary breaks, exterior bitumen damp-proofing, and sub-slab capillary breaks (allegedly … there are no tools in the auditor’s bag to check that one).
All that — and the basement still had huge humidity and moisture problems. There was evidence of standing water, flooding, spalling, and efflorescence. The moisture content of the sill plate was in the high 30s, despite the capillary break, and the basement’s relative humidity was a tick under 70% in March.
The bonus room over the garage was frigid and the heating system was delivering very little heat to it. The bonus room had an extended cathedral ceiling connected to the ceiling of the main living room.
And, as a cherry on top, the homeowners were blowing through a roll of paper towels every other day. The humidity was condensing on many of the windows, which were starting to mold. See … it’s not just heating bills, it’s the supermarket bill too.
Moisture – The issues at hand were many … oh so many. First off, the moisture. The house had been built into a hill. Anyone who was done some landscaping can see where this is headed. The footprint was perpendicular to the foot of a long swale on the hillside, funneling massive amounts of spring thaw or rainwater down its 300-foot-long slope.
The hillside face of the house had a solid 40-foot-wide depression against the foundation wall. The owner confirmed that on rainy days that water pooled 4 to 6 inches deep against the building. Tens of thousands of pounds of water would flow downhill, where the inexorable pressure would force water through the porous concrete. The interior confirmed this; in several places the concrete was damp to the touch.
This moisture was causing huge problems in the house. The moisture was radiating from the foundation, condensing on windows and other cool surfaces. Bad, moldy news.
Foundation heat loss – The concrete foundation was a massive source of heat loss. The house, like I mentioned, was built into a hillside. In a past article, I wrote about how concrete does a fantastic job holding a house up but a miserable job keeping heat in.
On the downhill face of the building, almost the entire foundation wall was exposed. An 8-inch thick concrete wall has an R-value of around 1. So a 1-foot thick foundation wall would be around R-1.5 (allowing for variations for the mix).
With a normal foundation, 18 or 24 inches of the foundation may be above grade (above ground). The downhill side of this home’s foundation was entirely exposed. The wall was nearly 35 feet long (excluding the garage), and between 4 to 8 feet of the wall extended above grade. That R-1.5 mentioned earlier is close to the R-value for a window. Imagine an almost 250-square-foot window. That’s some serious heat loss.
Bonus room over the garage – The finished room over the garage was something of a modern residential construction disaster. It was almost beautiful in its wrongness. Even years later, I still have trouble conceiving more things that could be wrong with a building built to code.
Where to begin? The master bedroom over the garage had a cathedral ceiling finished with tongue-and-groove boards. The cathedral ceiling extended to most of the first floor, and was perforated with recessed light cans and – what the hell – a skylight.
The tongue-and-groove boards had no air barrier behind them. Between the tongue-and-groove finish boards and the leaky recessed light fixtures, stack effect driven air was flowing pretty unimpeded right out of the house.
Fiberglass batts were installed flush on the back of the tongue-and-groove boards. When you lifted the batts, there were horizontal streaks where the glass fibers filtered out dust particles. The blower-door test confirmed the visual evidence, registering 6,200 cfm50 for a house a shade over 1,600 square feet. For the non-blower door folks, that’s a monstrous number for a house that size.
The bonus room over the garage was also compromised on almost every side. This is easier to deal with as bullet points:
- The marriage wall was open and unsealed at the top, allowing warmed interior air to escape.
- The chimney was built into the house’s gable wall and framed in the finish room. The top was entirely open (like 2 or 3 square feet open), and I could see the garage floor down the shaft.
- The ceiling of the garage was thoroughly perforated and not remotely an intact air barrier. For example, the door opener brackets had been fastened to the garage ceiling joists, and the drywall was fitted around the brackets. The holes were bad enough that you would see the underside of the bonus room’s plywood subfloor.
- The garage door did not have an insulated core, and was plenty loose; this made the basement garage what one might optimistically call “semi-conditioned” space.
- The interior garage framing walls were open over their tops, with only cripple studs attached to the joists.
- Bonus time: the baseboard hot water pipes had been run through the garage ceiling.
Needless to say, that was a pretty damn cold room.
Heating system – A brief bit on heating systems. Maine uses mostly oil. The rest of New England has a higher percentage of natural gas, but Maine has oil. I’ve never heard a good reason why, but I suspect it has to do with our mostly rural population. It’s not terribly economical to run gas lines 15 miles to widely spaced towns of 1,200.
In any case, oil. Oil heating means oil storage tanks and an exterior fill pipe and vent pipe for the tank. In every single house I’ve seen with a finished room over a garage, the oil pipes, tank and heating system are on the opposite side of the house. You can’t install them (or at least can’t easily install them) on the garage side; nowhere for the fill pipe.
The upshot is that the home’s boiler was installed on the far east side, opposite the garage. The heating system had one zone, covering the entire house. It ran clockwise, across the front, through the freezing garage ceiling, and around the back side of the house before returning to the boiler.
The hot water ran in uninsulated PEX pipes 6 inches from nearly 50 feet of uninsulated sills and concrete foundation wall, 30 feet of uninsulated top plate and another 50 feet of uninsulated concrete. Why were the north side rooms so cold? They had no sun and no heat was reaching them. Gah!
Moisture – One of the biggest challenges was tightening a building envelope with so much moisture. It’s a very bad sign when a house with a 6,200 cfm50 blower door reading, flying through 1,200 to 1,500 gallons of oil each year, is having condensation and mold problems.
Loads of energy pumped into a building enclosure and more air flow usually means more drying. If we just air sealed without any provisions for reducing moisture levels, the mold could potentially explode. It helps not at all to fix one problem and create another. This meant reducing moisture was the first priority.
Improving the exterior water management was tackled first (by getting rid of the pond in the front yard). Rainwater and snow melt were overwhelming the foundation’s existing footing drain, so it needed some help. The plan was to do the exterior work first, give it a couple months and track the interior humidity levels. If they came down, great. If not, we would include some more interior moisture management.
The homeowner was fully committed to fixing all of the existing problems, so out came the backhoe. The contractor hired for the external water mitigation trenched down to the footer drain. We were pleasantly surprised to find the footer drain nicely wrapped in a drainage screen and relatively clear of muck and blockage. It was functioning — just being overwhelmed by the hill drainage’s massive water volume pressure.
Once it was exposed, the entire sub-grade hillside section of the foundation was coated with two layers of UGL Drylok. This concrete sealant is waterproof and vapor semi-impermeable, providing much more protection against infiltration that the bitumen damp-proofing.
Once the trench was filled back in, we landscaped the hillside ground, creating an aggressive drainage slope. About 8 feet out from the house, leaving space for some landscaping later, we added a topside French drain. A 24 inch trench was dug across, and we laid a perforated 4-inch pipe at the bottom wrapped in drainage screen. The trench was filled with 1-inch crushed stone. Luckily, the hill provided a natural gravity drain out the sides.
We added a rain gutter with drains extended 10 feet down the side of the house. Normally adding a gutter can exacerbate ice dam problems. When clogged with snow, a gutter gives melting snow a natural stop point. But we would be address the attic insulation and air sealing, so (in balance) limiting foundation water was more important.
The next job was sealing the interior concrete. Normally, sealing concrete in high moisture situations may lead to upward capillary movement in the concrete. You see this in New England when older foundations are close to grade with no capillary break. That was not a worry here, as the pressure-treated sill plate was installed with a foam capillary break. The foundation floors were coated with 2 layers of Drylok. We left the walls alone, as we’d be applying closed-cell spray foam later, itself a vapor barrier.
Next we evaluated the improvements. We left several humidistats throughout the basement and house and the homeowner checked them regularly, recording the relative humidity. Once we had several weeks of data showing that the humidity and moisture had come down (no more window condensation), we moved on to insulation and weatherization.
Time would prove that an extra step like adding an interior perimeter drain was not necessary.
Ventilation – Because we would be tightening the envelope up a great deal, we made provisions for combustion air for the heating system and a heat exchange ventilation system.
One might not think that this house with its extreme air leakage would need mechanical ventilation. But we would be doing a lot of air sealing, and more importantly would be sealing the entire ceiling, cutting off any stack effect driven air flow. Adding mechanical ventilation set to meet the ASHRAE 62.2 ventilation standard made sense (and I say this with no intention of starting a ventilation flame war in the comments).
Air sealing and insulation: the attic – One stroke of luck was that the cathedral ceiling was constructed with scissor trusses and there was enough space to work from the top. This allowed easy access to the back of tongue-and-groove ceiling boards, the open chimney framing, the unsealed soffit vents, the skylight, and the recessed light canisters. All good news.
The existing fiberglass batts (two layers of crossed unfaced 9-inch fiberglass batts) were pulled aside carefully. The batts were in good shape, so they would be retained and re-installed.
The recessed lights were encapsulated with drywall boxes and caulked. The gap around the chimney was covered with light-gauge aluminum flashing and sealed with high-temperature caulk.
The soffit vents were sealed with solid foam blocks flush against the exterior wall’s top plate and the existing foam vents. The top of the marriage wall between the garage and main house was sealed.
Finally, 2 inches of closed-cell spray foam was applied to the attic side of the tongue-and-groove ceiling boards and skylight framing. Once the foam had cured, the fiberglass batts were replaced.
After all the air sealing and insulation work was completed, the blower door test out showed a leakage rate of 1,925 cfm50. Not ridiculously tight, but less than a third of the initial reading.
Air sealing and insulation: the basement – The basement/garage was next. I’ve never been a fan of defining the thermal enclosure at the garage door. The garage door is too difficult to insulate and air seal satisfactorily. The garage occupied the left-hand third of the basement, under the master bedroom.
We pulled down a one-foot strip of ceiling drywall and pulled out the fiberglass. I know we saved the fiberglass in the attic, but the garage ceiling was more problematic.
InsulWeb was tacked in over the gap in the drywall and we installed dense-packed cellulose. We patched and mudded the drywall; all the cracks and penetrations were sealed with foam sealant and caulk. The open space over the interior frame walls were blocked and sealed.
Lastly, all of the basement walls and sills were sprayed with 2 inches of closed-cell spray foam and intumescent fire-retardant paint.
Heating system – The single heating zone did a terrible job of supplying heat uniformly. Rather than re-zone, we decided to see how the house worked after the weatherization effort. The homeowner added 2-inch-thick closed-cell foam pipe insulation to the entire hot water loop and other hot water pipes.
We checked back periodically over the next couple of years. The husband has been closely tracking the energy data (or had been, as of about a year ago). The heating bills were around 40% of their previous levels and the moisture issues have largely disappeared.
In the interim, the folks had gone ahead and re-zoned the heating system into three zones and added an outdoor reset control. It was mostly “happily ever after” – except for the fact that it took a lot of work to arrive at that point.