Week 12, Fall 2011

 

Week Ending 12/16/11 

Well, it has been a long quarter and I am very proud of my students and their “stick-to-itiveness”.  These guys have done a great job of getting to class, showing attention to detail, and making sure the task is not only completed, but completed correctly. I don’t have much else to share about this phase of the construction other than it is a relief to have it done and now we can move on to the really fun stuff. I will leave you with some pictures of our progress to date.

Next quarter we will be working on solar PV, solar hot water, heating, plumbing, low voltage, and electrical, stay tuned.

Happy Holidays from the Sustainable Building Science program. 

Good bye, and good building,

Dan Smith

Week 6, Fall 2011

Week Ending 10/28/11 

This week we installed the exterior trim around the windows, door, corners, and belly bands. It was great work, great fun, and gave the students a little practice at refining their skills. One comment from a student was “you would never imagine that building a little house could be so complicated”. Well you wouldn’t think so but this is a new approach to building, and turning out to be quite a process. Most every step needs to be scrutinized to make sure it is achieving the goals you have set out.

The latest step that was revisited was the rain screen. I realized we may have a problem with bugs making their way through our rain screen product so we took off the bottom baton, covered it with screen fabric and reinstalled it on the house. Now we will have continuous ventilation behind the siding that is free from bugs and worries.

The trim around the windows and doors was installed without hitch or glitch. The wrap around the windows was fastened with galvanized finish nails and has a strip of the rain screen material around it for nailing siding to. The only noteworthy item on the belly band was the use of 4” galvanized nails because of the thickness of the built-up materials. It turned out to be a good choice because everything is well secured and ready for siding.

Next week we will be installing exterior siding, stay tuned.

Good bye, and good building,

Dan Smith

Week 5, Fall 2011

Week Ending 10/28/11 

Well, as it turns out, installing the rain screen was a little more involved than first glance. The first challenge was to cover the insulation to protect it from absorbing water and moisture while still having a product that was permeable to vapor. Covering the insulation with a layer of 15 lb. felt was a simple solution to the problem, but what was not so simple was how to fasten it to the wall assembly. It turns out that after you add an inch and a half of insulation to the side of a wall life becomes complicated. After a bit of trial and error we came up with the process of hanging a curtain of felt over the wall by using ¾” galvanized roofing nails as thumb tacks. It was a quick and easy way to fasten the paper without putting holes in the weather resistant barrier. The students did a great job of installing the paper on the walls in a time efficient manor with a minimum of waste. We have a great group here.

The next step was the rain screen. This part of the wall assembly is an air space behind the siding to give moisture a place to drain and also creates a pressure equalization plane that will stop vapor drive during intense solar exposure. Again, the idea is simple but the devil is in the details. We started with the bottom and top band which was not difficult but when the batons were being fastened over the tops of the studs particular attention needed to be kept as to the location of studs and the direct connection of the batons.

The window detail of the batons was another design challenge. We are installing 5/4 by 4 trim around the windows so we had to make sure the batons would have enough reveal left to attach the siding. What we did was to rip down the baton to one inch wide and nail a strip around the window opening before nailing the 1 ½” wide strips. After the window trim is installed there will be approximately a one inch nailing flange for siding. We also had to pay close attention to the profile of the baton around the window. We had to make sure it was flat with the flange of the window so the window trim would look flat and seamless.

It was a very good and productive two weeks and could have not been done without the help and problem solving skills of my students. I commend them for their generosity of ideas and stick-to-it attitude for continuing with their good work. 

Next week we will be installing exterior trim, stay tuned.

Good bye, and good building,

Dan Smith

Week 3, Fall 2011

This week the class completed the installation of the rigid insulation on the exterior of the house. We now have a house that has a fully enclosed envelope and is free from thermal bridging. The insulation will block the summer heat from entering the building and keep the winter heat from leaving the building. 

As you can see from the pictures we put a piece of flashing between the foundation and wall insulation to direct any water accumulation out and away from the building. Other points of interest in this system are the blocks between the gable lookouts, the trim piece under the truss heels, and the build-up behind the windows and doors. The blocks between the lookouts were put in to make the installation easier and use as a trim piece after the siding is attached. The trim at the heels was installed to cover the top edge of the insulation and also be used as a finish piece with the siding. The build-up for the windows and doors needed to be put in to compensate for the extra space taken up by the insulation and rain screen.

I want to take a moment and say what a pleasure it is to work with the students of the Sustainable Building Science program. Without them, their enthusiasm, and their great ideas and input the progress on this project would not be possible. They are a great team and I wanted to make sure they were recognized for that.

Next week we will be installing the rain screen material and exterior trim, stay tuned.

Good bye, and good building,

Dan Smith

Week 2, Fall 2011

This week the class has concentrated on installing the insulation and air barrier in the crawl space of the Zero Energy House. This is quite a significant segment of the assembly because it will block soil gases, keep moisture out of the crawl space, and complete the thermal boundary at the base of the structure. We have no venting in our crawl space which makes it a conditioned air space. This will allow us to install the ducting for the forced air furnace and not insulate it. Since the ducts are already in conditioned air space there is no penalty for any leaks.

When looking at the pictures of the week in progress the assembly process can be seen. First we positioned two inch thick by two foot wide by eight foot long panels of rigid insulation on the crushed rock floor of the crawl space. The gaps between the rigid insulation were then filled with expanding foam to help complete the insulation layer. The insulation was then covered a with 6 mil polyurethane vapor barrier that was fastened to the footing with furring strips around the perimeter of the inside footing.

This was a very productive week and informative in that we demonstrated that there is a definite need for vapor barriers in the crawl space. Before work was started the moisture level in the crawler was very predominant. The moisture level and soil gases were very sensible. The moisture levels were measured at 25% to 35% in the material and an ambient relative humidity at 75%. After installation of insulation and vapor barrier the odor of ground gases was gone and the humidity level was sensibly less. We will continue to test the moisture levels of the air and materials and post them in the coming weeks.

Good bye, and good building,

Dan Smith

Week 1, Fall 2011

This is the first week back from summer break and I am pleased to say that we have a full class of very enthusiastic students. For lab this week we started finishing off our super insulated envelope enclosure on the Zero Energy House.

What is seen on the outside of the building is an air sealing product called WET-FLASH that has been donated by our friends at Building Envelope Innovations. This is a role-on product that seals the walls off and limits air travel through the envelope while still allowing the assembly to dry and not hold moisture.

The windows shown were purchased from Milgard Manufacturing and are triple glazed and have a U-factor of .25. The doors are also from Milgard and are fiberglass with an insulated core and have a U-factor of .29.

The insulation installed on the foundation wall is two inch rigid and is fastened to the stem wall with deck screws and fender washers. The walls are covered with two layers of ¾” thick R MAX rigid insulation. The two layers are installed so the seams of the insulation are overlapped both horizontally and vertically.

This is a wonderful project and students are very excited to be a part of it. The web site will be updated on a weekly basis to keep people informed about progress.