As I’m writing this, the 2009 Solar Decathlon in Washington, DC is nearing its completion. Twenty teams from around the globe are competing to build the best Solar Home, judged in ten different categories, including: architecture, engineering, net metering, living comfort as well as others. This year, Massachusetts – home to some of the greatest colleges and universities in the world – is represented by Team Boston – the joined efforts of Tufts, Boston Architectural College and a team of volunteers, all with the common goal to create green and sustainable home designs that could be readily available and affordable for actual home buyers and home builders.
Cool Flat Roofs and IB Roof Systems are proud sponsors of Team Boston’s solar home. We provided the project with IB flat roofing materials (provided by IB Roof Systems) and a professional installation, as well as last minute roof design changes, and modifications to roof penetration placement and drainage setup.
The Boston solar home construction is all finished, the Solar Decathlon competition is almost over – the houses will be disassembled and transported to their final placements. Team Boston solar home has already found its buyer in Cape Cod, where it will be available for public tours. Building this home was a bit less glamorous, and here I will tell you about our part – the installation of a flat roof.
The roof was designed to allow for the house to be transported in 3 sections, and to host 3 rows of solar panels, as well as collect all rain water. The house design team had to work really hard to make all three major requirements work together. The roof and the house were separated into 3 different sections, with separating parapet wall inside and around the perimeter. To avoid roof penetrations and as a result – roof leaks, the solar PV and hot-water racking systems had to be placed on top of parapet walls – both interior and exterior.
The roof drains and all roof penetrations had to be placed so they would be away from future solar system racking steel beams. The roof itself was designed so that all water in each section would run toward the drain, with an overflow scuppers as back-up drains.
We utilized the 1/4″ (1/4″ rise to 1′ run) tapered insulation system, which would go from 1″ at the lowest spot to 5″ at the highest point. The roof drains were placed at the lowest points of each roof section, while all penetrations were moved to the highest points on the roof.
Roofing Material: Because of multiple inside corners and penetrations, IB Flat Roofing PVC membrane was chosen and the best roofing system for the job, as it allows for all flashing components to be hot-air welded together, eliminating the possibility of leaks due to seam failure. Even if the roof would be damaged during the construction process (there was constant foot traffic on the roof, after we finished installing it – plumbers, electricians and Solar PV installers), it would be easy to repair – as easy as welding a patch over the damaged area – a one minute job.
IB Flat Roof Installation – Day 1
Due to scheduling and timing constraints, all construction on the Boston Solar Home was performed on Fridays, Saturdays and Sundays of each week. We started installing our roof on a Sunday, after 2 days of rain, and as we pulled up to the construction site at Tufts in Medford, MA, it was still drizzling, and the team members were vacuuming and pushing water off the roof. This itself was a challenge. After pulling the tarps off the roof, there were about 4 inches of rain water trapped between parapet walls of the roof and tightly sealed moisture resistant roof decking. Water was slowly dripping inside the house, but a major part of it was still on the roof. Two holes were drilled through the roof sheeting in the overhang section, where the drains would soon be installed. The water quickly drained over the grass, but a third section of the roof had to be manually cleared of water with a wet vac and push-brooms.
Installing Roof Insulation: As we unloaded our tools and materials, the guys from team Boston were finishing the drying process, the drizzle stopped and we were ready to start installing insulation – a tapered system that would span between 1.5 and 5 inches. We used different thickness ISO insulation board, starting with 1″ at the bottom, and going up / leveling it off with tapered and straight insulation. All insulation was attached with heavy duty, corrosion resistant screws and plates. At the highest point the R-value of the insulation would be 30-R (6-r value per 1 inch of insulation). Additionally, there are approximately 12 inches of sprayed foam insulation between the rafters, which makes the roof of this solar home super insulated and protects the weakest point in the house when it comes to heat loss, as most heat escapes through the roof.
Installing IB Roofing Membrane: Due to weather conditions, we had to start work late, and it was apparent that we would not finish the whole roof in one day – even with the help of about 6 architecture students from BAC, and Tom Paisley – a green builder from Middleboro, MA, who introduced me to people from Team Boston.
We were able to finish one section of the roof completely, including all the parapet wall flashing and inside corner detail, installed a temporary roof drain, as well as welded all the seams. Since the plumbing for the IB U-flow drains was not in place yet, we installed IB membrane drain liner, and fitted it into a temporary PVC pipe. On the second section of the roof, we only had time to lay down the field sheets of membrane and a drain liner, and left the parapet wall flashing and corners for the next day.
IB Flat Roof Installation – Day 2
As we arrived to the job site the next morning, the sun was beaming down on us, and the temperature was nearing 95 degrees – there was not even a sign of rain from previous days. I was so happy that the roofs we install are white and barely gain any heat from the sun – otherwise it would be nearly impossible to work in these weather conditions. Nevertheless, I went through at least a gallon of water that day.
Architecture students and volunteers were laying down the insulation, as I jumped onto the roof, and started planning out the membrane layout to minimize waste. Since an IB Roof comes in 6 feet wide rolls, and the width of the roof sections was about 9-10 feet, there would be 2-3 feet of material I had to cut off. We would cut it in half, and use it for parapet wall flashing.
Once all insulation was in place, we could finish installing the IB membrane and welding all the seams to make the roof completely watertight. In total, we had to flash 12 inside corners (and later, as we were doing the overflow drains, we had to install 6 outside corner flashings), 3 through-roof IB U-flow drains and 4 through roof penetrations: 1 for the bathroom vent and 3 others for Solar PV and Solar Hot Water hook-ups.
All seams were welded with the Swiss made Liester hot-air welding equipment which is a de facto standard in the thermoplastic roofing world. For long seams we used the Liester Triac Drive – an ultra portable semi-automatic welder, which can make a roofer’s life much easier. When we need to weld a small section of a seam, the hand welders are perfect. But when it comes to longer seams, doing it by hand becomes, if not problematic, but very painful – literally. Hand welding can put a lot of stress on your wrists and that is why we invested into the very expensive automatic welding equipment.
Solar Home Roof installation video: Welding IB roof seams
One major obstacle we still had to overcome was the the fact that the Solar Home was built to be transportable in 3 sections. The IB roof membrane would have to be cut along the inside parapet walls, to take the house apart, and when the house is put together, it would have to be watertight, and preferably without having a roofer and hot air welding equipment on site. Although the parapet walls would be copped with aluminum parapet caps, it would not be a sufficient way to keep the house watertight and leaks free – maybe just for a short period. But the team could not afford to have roof leaks in the middle of the Solar Decathlon competition or after. We had to figure out a way for the roof to be watertight not once, but every time the house is transported and put in place, without additional welding. This we took care of later, once the Solar PV and Hot Water panels rack system was installed.
We finished day two of roof installation as it was getting dark, and most architecture students had already left the job-site. Now we had to wait until the solar panels were ready to be installed.
IB Roof with Solar PV and Solar Hot Water panels – Day 3
Once the IB roof was installed and the Boston Solar Home was watertight, we took a little break and concentrated on our everyday roof installation. During this time, the Team Boston was hard at work on the interior of the house as well as getting ready for the final stage of the roof installation – Solar PV and Solar Hot Water installation, which would use Steel / Aluminum Racking systems bolted to the parapet walls.
By the time we got to the job site on the 3rd day, the mounting racks were already in place and some Solar PV panels were also installed. We had to work around them and in some cases actually move the racking system and Solar Panels, so we could get into tight spaces.
We had to install all three IB u-flow drains (which due to their size did not fit between the solar racking system), pipe penetration flashings for exhaust pipe and solar electrical and plumbing hook-ups. We also had to install the overflow drain scuppers and as I discussed before, we had to figure out a way for the house to be watertight after it was transported to Washington, DC fro the Solar Decathlon and to its future owners, preferably without roofer involvement.
We decided to weld a wide strip of IB membrane over parapet walls – one side would be welded while the other would remain not welded, but flipped over to the other section. This way the cut between house sections would always be watertight and with the addition of parapet caps, the wind driven water would never penetrate the roof. We also had to figure out how the “T” joint of the 3 house sections would work, and the overlapping joint covers were installed, each welded to its own section of the house.
As we finished installing all roof flashings, the house was all watertight and almost ready for the transportation to the Solar Village in Washington DC. There was still a lot of work to be done, like all the heating, interior, and other construction work, but our part was over. I did plan to volunteer some of my time to help team Boston with building this beautiful home, but as the busiest time of the roofing season rolled on, I could harly find time for my full time job. I did not see the Boston Solar Home, until I actually went to DC for the Solar Decathlon, during the Columbus Day weekend.
Quick highlights of the Boston Solar Home:
- Size – approximately 800 sq. ft. Competition regulations limit solar home size to 800 sq. ft. and most contenders, except one, built their homes to maximum allotted size.
- Solar PV system size: 6.4 KW DC, with individual mini inverters to maximize electric output, and minimize shading losses.
- Wall insulation: 2 inches (13-r) of ISO board with aluminum foil (more insulating value than regular ISO board) and 8 inches of in-wall insulation.
- Trombe wall – a liquid-filled solar thermal mass windows, that collect and store solar heat during the day and heat the house at night.
- Solar Hot Water – 5 hot water panels that provide heating and hot water for the house.
Because of size limitations, each team had to use the most efficient solar panels available on the market (not development products). This posed additional obstacles for the designers and builders, and forced the use of a rack-mounting system to house solar panels. If the house was not limited to certain size, the use of IB Solar Wise PV system – the building integrated solar PV modules built by Uni-Solar, would greatly reduce the final cost of the solar system and simplify the installation. IB SolarWise eliminates the need to use a rack mounting system as it is a thin-film solar system adhered to IB patented membrane – Solar Shield – which distributed the heat gain of solar panels and prevents delamination, which is often the case when UniSolar panels are installed over rubber roofs of TPO single ply roofing systems.
Getting an IB Roof and an IB Solar PV system installed in MA, CT and RI:
If you are interested in having an IB PVC roofing membrane or IB SolarWise PV system installed on your home or business, feel free to fill out our online roofing estimate form to get free price quote. You can also use our interactive roofing price calculator to estimate the cost of your roof replacement and compare IB roof prices to those of EPDM Rubber, Modified Bitumen and Tar+Gravel roofs. We recently updated our calculator to account for smaller sized roofs, and to also include options for chimney or skylight flashing, parapet wall flashing and other roof penetrations.
You can check out the roofs that we have installed all over New England by looking at our job profiles, which we regularly post for each state: