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First Year Report: Remodel--Unico/Foam Roof/Electrical/Solar

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Joined: May 13 2007

In the spring of 2007 we decided to embark on an ambitious project for our 1960 Terra Linda Eichler: a new foam roof, the Unico heating and AC system, an upgraded electrical panel and wiring, and a photovoltaic solar system. (We also completely redid our kitchen and master bathroom, but I won't cover that here.) The original electrical system was showing its age, with frequently overloaded circuits. The radiant heat failed back in the 1980s and was replaced with an inadequate forced air system, which only heated half the house; the other half we heated with electrical space heaters, which guzzled electricity and never really did a good job. The tar and gravel roof was in reasonably good shape, but provided no insulation, making the house an oven on hot summer days. Like many Eichler owners, we decided to do these various projects all at once, since most of them involved modifying the roof in some way. (The four most expensive words in home renovation: "While we're at it...")

It's now been over a year since we completed the work. At the time we were researching the project, I hunted mostly in vain for solid information from other homeowners who had done what we were planning to do. I am writing this article so that others who are considering renovations similar to ours may benefit from our experience, and from our mistakes.

Description of Systems

The Unico System and Foam Roof:
For budget reasons, we originally planned to install a standard HVAC system on the roof. However, we quickly discovered that, as a result of the backlash against a second story added to a Terra Linda Eichler a few years ago, there is now a San Rafael building ordinance forbidding the placement of anything on the roof that rises more than 6 inches above the surface, unless you are willing to go through a review process with the Planning Commission. It sounded unlikely that we would prevail if we pursued that route, so the only options this left for heating and AC was either to install several mini-split systems around the house, which would be awkward, unsightly, and expensive, or to go with the Unico system, which was elegant, unobtrusive, and staggeringly expensive (more on this below).

The Unico system is installed in conjunction with a foam roof. All ducting is low profile -- no more than four inches tall -- so it goes under the foam roof and once it is installed, is invisible. There is a main sheet metal trunk line, about 18 inches wide, that runs from the blower unit across the roof, and then mutliple flexible round ducts emerging from it, each one terminating in a small (2 inches wide) round vent hole in the ceiling below. Because they are so small, there are usually 4-5 vents in each room -- more in the large rooms, and fewer in small rooms such as bathrooms. There is also a three foot wide sheet metal air return duct, which requires a 2 X 2 foot grille somewhere on the ceiling. The visual effect on the roof, before the foam covers everything, is of a giant octopus with dozens of silver tentacles.

There are two choices to power this: an all-electric heat pump, or a combination of a standard AC compressor unit and a tankless water heater to handle the heating. The HVAC installers said the tankless water heater option provided a better experience of heating, and we were originally interested in this option, since we had to replace our water heater anyway. However, the demands of the system require that the tankless water heater be dedicated to the Unico system and not share regular hot water supply duties, and due to the cost of running new gas lines and the high cost of the tankless heaters, we opted to go with the all-electric heat pump option. This consists of two main units: the heat pump itself, with is a big noisy rectangular unit that is situated outside the house, and the rest of the system, a sprawling conglomeration of sheet metal and machinery that lives in our utility closet in the converted garage. (Actually, it is so big that we had to extend the utility closet into the closet next to it to fit all equipment.)

The foam roof consists of a thick (around 4 inches) layer of styrofoam slabs which are cut to fit around the trunk and supply ducting described above, and then covered over with plywood for rigid protection, then sprayed with a layer of hard foam, which is then sealed with a rubber-like coat, which is then covered with a sprinkling of reflective sand. The final effect is like a snow covered landscape; in fact, you need sunglasses to be on the finished roof without getting blinded. Because the surface of the roof ends up being raised up to 8-10 inches overall, the roofers add an extra 8 inches of trim around the edges, and if you have skylights, they raise these by a foot also.

The Electrical Upgrade
We replaced our old electrical box with a new 200 amp box, to give us the ability to increase the load of some existing circuits and add new ones. We added several new robust circuits to the kitchen and master bath, and ran new overhead lighting circuits to three bedrooms, the living room, the enclosed atrium, and a hallway, all of which had typically inadequate Eichler overhead lighting (that is to say, none at all). We installed a vent hood in the kitchen and venting fans in the master bathroom and in the atrium, which because it is enclosed gets hot in the summer. We had planned to install a wired smoke alarm system, but due to cost overruns opted to go with battery powered wirelessly connected smoke alarms instead.

The PV Solar System
Because we were so radically changing our house and its systems, it was difficult to estimate the proper sizing for a photovoltaic solar system. Our original fantasy was that we could generate enough electricity to meet all our power needs, but we eventually realized this was neither practical nor economical. We had wanted a 5 KWH system, however, we learned that the solar panels need to be installed in banks of 9, and for the time being we could only afford to install 18 panels, a 3.3 KWH system. The system includes an inverter unit to convert the electricity to a form usable by the electrical grid, and we opted for one that could handle a 5 KWH system. The panels are installed on metal feet which are bolted into the wooden beams underneath the foam roof, and we also had the installers mount an extra set of feet so that down the road we can install another set of 9 panels. The system is wired into our PG&E meter so that it feeds into the electrical grid running through our meter; if it is producing more electricity than our house is using, our meter runs backwards and we get credit for electricity generated. The meter is a special Time of Use (TOU) meter, which charges much higher rates between 12 noon and 6 pm Monday to Friday ("Peak" hours), and lower rates all other times. (More on this below.)


First the roofers came and removed the loose roof gravel, and installed the extra raised rim and flashing around the edge of the roof. The solar installers came and bolted the feet for the solar panel racks to the roof, chipping through the old tar and gravel roof layers to bolt directly into the wood, and sinking the bolts into the main beams below for maximum stability. Next, the electricians and Unico installers began running their ducting and conduit on the roof. This took the longest time, since the electricians had to do a lot of hacking through the old roof layer to get at some aging and buried wiring they needed to replace, and to run the new conduit. Once the electrical and ducting work was done, the roofers returned to build the skylights higher, and installed the new roof. The electricians installed the new breaker box, PG&E replaced the meter with the new TOU meter, and the solar installers hooked up the solar inverter to the new meter. The whole process took slightly less than two months, with somebody performing at least some work almost every weekday. Frustratingly (but apparently typically), it then took several weeks after completion of construction for PG&E to actually approve and activate the solar system.

Installation Cost

Unico System $28,815
Foam Roof $25,172
Electrical $22,534
PV Solar (after rebates) $21,498

TOTAL = $98,019

The combined cost of the Unico and the roof was particularly jaw-dropping for us, since the Eichler Network postings I had read on the topic had quoted a total of $30,000 for roof and Unico. The figures above are 2007 costs, and I was told by the roofers after we signed the contract with them that the cost of the Unico roof kit had just gone up another $5,000, so the overall cost is probably more now. Had we been able to install a "normal" HVAC system on the roof and didn't need the special Unico roof kit, the combined costs would have been almost $17,000 less, so this is (or was, in 2007) the premium you pay for the Unico system.

Results and Operating Costs

So was it all worth it? For us, yes.

The house is noticeably cooler during the summer and retains heat better in the winter, thanks to the foam roof. We probably only ran the AC a total of 14-20 days during the summer, but on those days it did a good job of bringing the house to a comfortable temperature. The heat is a gigantic improvement over our previous patchwork system. The programmable thermostat kicks in early in the morning before we get up, and by the time we are up, the house is consistently warm throughout. The heating and cooling is not particularly intense or dramatic when it is running; if you put your hand under one of the vents, you can feel the air coming out, neither chillingly cold with the AC nor blazingly hot with the heat, but depending on the extremes of the temperatures outside, the house generally reaches a comfortable temperature within an hour or less. An overall background humming noise throughout the house is noticeable when it is running, and the machinery in the utility closet is somewhat noisy, but not objectionably so; the converted garage is our TV room, and we are able to watch TV there while the HVAC system is running.

The downside to the all-electric heat pump and machinery is that it has a hearty appetite for electricity. If we didn't have the solar system offsetting our electrical bill, we might be experiencing major sticker shock. Over the course of a year, the solar system has generated about a third of our electrical usage. (If and when we expand the system to the full 5 KWH originally planned, it should produce about 50%.) However, because of the Time Of Use electricity plan we are on, the peak generation times for the solar system are when the rates are the highest, which means that we get credited at a higher per kilowatt rate during the day than we get charged when most of our electrical usage is happening -- in the mornings, evenings and weekends. So even though it only generates a third of our electricity, the solar array probably pays for half or more of our electrical costs. The solar system does about 80% of its annual electricity production from May-September, with negligible output in the winter months, when the skies are overcast and the sun low on the horizon.

Unfortunately, I can't say for sure how much it all adds up to for us to run, because nobody told us that by going to an all-electric heating system we qualified for a special electrical rate from PG&E, one which has a much higher baseline than the normal rate. I only discovered this by accident in the month of March, and PG&E refused to give us a retroactive adjustment back to September, when we went all-electric. Since they gave us a $75 refund for charges for March, I am guessing that last year we probably paid as much as $500-$700 over what we should have, and expect this next winter's charges to be significantly lower. During the months of May through September, we actually ran a net negative balance on our PG&E bill due to the solar generation. (Note, however, that when you have a solar system, PG&E charges you monthly for your gas usage and some fees for the electrical, but the bulk of the electrical charges are accrued over the year, at the end of which you "true up" with the utility, i.e., either you pay them if you have a balance, or they pay you if you generated more electricity than you used.)

For those into exact figures, here is the breakdown of therms and kilowatts for the old system (the prior year) and new system (in its first year of operation). The old system used gas to heat part of the house, and in the remodel we added a gas range, but we also replaced an old and probably inefficient gas water heater, so our gas use is now pretty minimal.

Old system
KWH 13194
Electrical Cost $2,488
Therms 706
Gas Cost $901
Total Monthly Avg. $282

New system
KWH 18055 (12501/5554)*
Electrical Cost $2,273**
Therms 159
Gas Cost $216
Total Monthly Avg. $208**

* Numbers are: Total KWH Used (From PG&E / From PV system)
** If billed at the proper rate, the annual electrical and the monthly average figures should probably be more like $1,750 and $165.

Problems and Lessons Learned

1. Make sure one person is in charge of everything
Because I am detail-oriented and have some project management experience, I opted to forgo hiring a general contractor and operated as the project GC myself. Overall the project went well, but this approach is not for the faint of heart -- to pull it off, you need to be willing to spend significant time each day reviewing progress, getting people to communicate with one another, noticing and anticipating problems, and fielding an endless series of questions and decisions.

Whether you do it yourself or hire a professional, it is absolutely essential that there be one person who has an investment in the project going well and who takes responsibility for it. The reality is that the individual contractors and companies care and think about their own piece of the elephant, and no one takes time to consider how their part fits into the big picture, or how what they do may negatively impact somebody else. Even though three of the companies involved had collaborated on similar projects before, they still needed a lot of facilitation in coordinating their efforts.

2. Make sure each contractor knows specifically what the others are going to do, and where, and how.
The first day of the project I convened a meeting with representatives of the electrical company, the HVAC company, and the solar company. After discussing the scope of the project, we trooped up to the roof together to discuss placement of the installs and how the workers would coordinate with one another. The solar installers determined where they could sink the feet for the racks without getting in the way of the HVAC ducting, and the electricians and HVAC people agreed to work around each other in the placement of the ducting and electrical conduit. I asked the roofers if they wanted to be represented at the meeting; they said it didn't seem necessary, and I didn't push the issue. Big mistake: almost all the major problems that developed in the course of the project could be traced back to the roofers not being present at that meeting.

Everybody assumed that the roofers were going to strip the old roof off completely. The roofers had offered this as an option, but discouraged us from doing so, saying that it is a horrible, messy process in which all kinds of gravel, tar and junk rains down through the exposed ceiling boards, and that it was not really necessary. However, the electricians based their bids on the assumption that they would be running conduit over exposed roof boards, not having to painstakingly hack through layers of old tar and gravel roof. Having to do so significantly slowed them down and added to the cost of the project; their being slowed down meant that the HVAC installers got ahead of them in laying duct work so that later on the electricians had to temporarily raise the duct work to run conduit underneath it; this led to the seals on the ducting being broken and needing resealing; and this ultimately led to my being up on the roof the night before the roofers were due, running the Unico system and daubing sealant on the whistling and hissing joints of the ductwork because the HVAC guys hadn't done a very good job of resealing it.

Also problematic was that the HVAC installers ran the main trunk and return lines of the metal ductwork a foot away from the raised clerestory windows of the living room. The roofers, when they arrived prior to the final phase of the roofing, informed me they would need to permanently board over these windows because otherwise there would be a sunken area that would collect water. After much pleading and bargaining on my part, they came up with a way to create a kind of gutter there that would allow us to keep our windows, but the roofers weren't very happy about the integrity of this solution, and in fact we ended up having a big leak in one of the windows, which I needed to patch later as a result.

3. Roofers do roofing well, other tasks not so well
Despite their efforts at masking off outside beams and surfaces, the roofers ended up spattering the spray-on foam on some exterior painted surfaces, particularly in the areas around the clerestory windows, where they had to work in very close quarters. This required my doing some scraping and repainting afterwards. When they boarded over the hole left when they removed the old kitchen vent fan, the tongue-in-groove planks they filled in with were a different thickness than the originals, leaving a 1/4 inch offset edge that I needed to spackle and sand when I repainted the kitchen ceiling. When they raised the skylights, they just put in bare wood extensions, which required spackling, sanding and painting to blend in with the previous skylight wells. More problematically, they didn't put any kind of gasket or caulking around the edges of the skylights, with the result that almost every one of our nine skylights had a 1/8 - 1/4 inch gap all around the edge where it sat on the wooden frame, allowing for refreshing outdoor breezes to enter the house, and all our nice heat to exit. Because the gaps weren't visible from below, and because I waited almost a year to get up on a ladder and start the painting process on the skylight wells, I didn't discover this huge insulation problem until after we had gone through an entire winter, which means we probably paid a whole lot more for heating than we needed to.

4. Get permits for everything
All the contractors pulled their own permits, although the roofers hinted that it would be okay with them if we didn't have them bother. The first rain of the season came the day before the permit inspector arrived to look at the roof, and he flunked it for having excessive ponding. The roofers marked the areas that needed to be built up to correct the problem, but because the rainy season was upon us, we agreed to wait till spring to actually have them finish the work. Spring came, and various phone calls from me to the roofers always met with a friendly response and assurances that they would be out to do it, real soon. A polite but firm letter produced a similar response. A second polite but firm letter, prominently cc'ed to the building inspector, resulted in a phone call from the roofers the very next morning asking if it would be OK if they were to come out an hour later to do the work, and they did. I suspect I might still be pleading with them to finish the work had we not had the leverage of the building department.

So there you have it. I will be happy to communicate directly with anyone with questions about the project, including which companies we hired, via email. Pictures of the progress of this project can be viewed at:

Joined: Aug 6 2006

That's almost exactly what I had gone through during the past year as well. I was fortunate to have a few contractors and engineers in my family to help me cut the labor cost dramatically otherwise I would not have been able to afford my improvements. I also just installed a hot water recirculator on a timer which saves around 4 gallons per day as well as a couple of rain water collection barrels. Aside from the lawn in my backyard I'm planning a xeriscape frontyard using drip irrigation and native plants.

I currently have a 3 KW photovoltaic system on my roof with an almost full southern exposure. We don't use our Unico system very much since the insulation in our walls, floors, and roof have been enough. Our PG&E bill is currently at around -$300 but we'll see what happens when the winter chill rolls around. We also had no choice but to replace some of our windows so we put in a few double glazed ones with a low-E film.

Energy costs are high. Putting more of a conservation/green spin on your home improvements will help lower your bills in the long run, reduce dependence on fossil fuels, and may even raise the value of your home.

I applaud your efforts.

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius - and a lot of courage-to move in the opposite direction."-E. F. Schumacher.

Joined: Aug 19 2008

Thanks for sharing your experience. We went through the ringer w/ a very similar re-roof job. We used spacepak instead of unico and had to add a firesprinkler system. We're planning to add the PV panels later, but put in the mounts w/ the same approach as you. We did remove the original roof, and it did make a major mess - fortunately, the house was gutted and unoccupied so the dirt and debris didn't cause any problem. I did have to vacuum the every groove from the top and bottom to get the gravel out though. We ended up caulking the grooves from underneath which effectively stopped any future debris from falling through. Here's our blog:


Atrium Eichler

Joined: Jul 18 2009

To the original poster, would love your email to find out who you used to install the foam roof. I am currently trying to figure out who to use to re-roof my terra linda eichler. Thanks.

Joined: Jun 3 2010

Excellent information - thanks for all your effort keeping the community informed!


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