Sunday, April 25, 2010

Second Roof

Hi all,
Second roof took the best part of the week. The first roof and wall assembly gave us a continuous air seal and insulation cavity without the punctures that rafters produce in the envelope.

Three reasons for putting on a second roof framing and foam:
1- Second roof is added to achieve a higher overall R value,
2- It eliminates the roof's cavities from reaching dew point and condensation within the cavities,
3- It achieves our 2 foot over hangs.

We stayed home Tuesday waiting for a rain that never happened. Next week we begin exterior treatment and hopefully get our composition roof shingles finished.
See you next week.........Terry

The plywood and all the framing members were sprayed down with a 10% solution of boron. Damp and dry wood termites leave their nest colonies and fly off every year to recolonize. They hit a building at all levels in mass looking for holes and cracks to crawl into and start a new family in wood fiber and darkness. First defense for a structure is no holes or cracks in the assembly. Second defense is to soak down all the wood with a boron base application. Boron is not a neurotoxin, like most insecticides, and does not directly affect the nervous systems of termites and wood boring beetles or humans or pets. Boron is an enzyme inhibitor. When termites bore into the wood they are forced to eat the boron as well. Boron messes with all the body functions of the critters including their digestive system and they sadly wither away with a host of problems.

Termites prefer to start their inward journey through end grain so we double soaked the rafter tails with boron before the facia was applied.

Second roof applied over our first air seal roof. Now we have two foot rafter overhangs. This layer does not need to be air sealed. The 2x4 "sleepers" were attached with a nail gun from the underside of the plywood. They are set in between the 2x8 rafters below to minimize the thermal bridging between the two roof assemblies.

3 1/2" polyisocyanurate (rigid foam) set in between 2x4 sleepers.

Sleepers and foam ready for plywood.

Sunday, April 18, 2010

Air sealing the exterior shell

Hello again,
Another good week. We finished air sealing the exterior shell, tested it for air leaks, installed the windows and got on half the second roof on and covered it for a pending rain. On Friday and Saturday more than 140 people, CLAM members and building professionals from all over the Bay Area, came out for the "See the Guts" Tour to see how the Passive House is put together from the ground up, focusing on the air sealing of the exterior shell.
See you next week..............Terry

Our first blower door test with no windows cut in revealed our "D" ring was too big and we got fluctuating read outs. For those who do not know what that means: a "D" ring is used in super air tight tests. I called up the manufacturer of the blower door company and they said "Holy ~*^- ! you guys are in "E" ring territory, we don't see that very often."

Here Bill is putting tape over our D ring in an attempt to make it smaller so we might get the LOW flash to stop going off. It worked and we got .11 and .12 CFM readings (not accurate but revealing). Again, for those who do not know what that means: you could not find a hole big enough to let a fly egg pass through.

After the first blower door test we cut out the plywood sidewall in preparation of the windows. We used Serious Windows with an R- value of 7 and equally as important, Serious windows are very air tight. here Jorge, Sebastian and Bill are tilting the window into a wet bed of caulk.

I did a second blower door test after all the windows were installed to see how much they leaked.The new test numbers showed a negligible difference, verifying air tight windows and installation. Note: I blue tape sealed the blower door shroud all around the jamb and tightened a bungee cord around the fan shroud to assure no leakage in the assembly. I also ordered the E ring for the next test.

Ready for next roof. Shell exterior air sealing is done.

Next roof- this time with two foot overhangs.

3 1/2" polyisocyanurate (rigid foam) in between the 2x4 sleepers/ overhangs.

James Bill of ZIA (zero impact architecture)and the Passive House architect for Blue2, explaining the coolness of the Passive House on the "See the Guts" Tour.

Charles of Mr Insulation showing a demonstration/sample wall section of insulation at the tour. We screwed up two sheets of ply, drilled three 1 1/2" holes and Charles blew in dense pack cellulose behind the plywood. We then pulled the ply off to reveal these packed cavities. We will be using cellulose for all the interior insulation.

Tuesday, April 13, 2010


Hello all,
Framing is a beautiful thing to look at. It is orderly, soft and when open to the sky it has wispy overtones of suppleness with hints of fortitude.
This week was about framing. It is an upbeat activity that ends the week on a good note.
Thank you all...........Terry

Notice no rafter tails sticking out. This eliminates punctures in the air seal and insulation of the roof and wall assembly. Confusing? Imagine a two by four going through your bedroom wall and resting on a planter box outside. It would be hard to seal around it so it did not leak air. Imagine the combined air leakage with forty of these punctures in the wall. A roof rafter does just that except it happens up high and is incorporated with the roof so it looks good and we have come to accept- it as normal. We will be adding the rafters later on top of the first roof. Pics to follow.
Also notice the made up foam header at left with metal plate was made out of our form boards as well as the high up end blocking between the rafters. The foam in all the headers was from a project I did a few years ago- sometimes it pays to save stuff. Also notice each roof rafter lands on a wall stud, thus eliminating the need for a double top plate.

Cut, foam and nail.

All the edges and openings of the framing were foamed to receive the sheets of plywood.

A sheet of ply being tilted into foam bed.

We got tired of turkey sandwiches and Snickers so Adriana, Jorge's wife, on left, made us tomales and salad with fresh mangoes. Jorge with family, Toni (videographer) and Bill in center, Sebastian in red and Felix who joined us for the day and myself.

Note-no headers on end/rake wall. If I had built this house a year ago there would have been.

Sunday, April 4, 2010

Slab & Start Framing

Hi again,
Between rain and County inspection it was a three day work week. We formed the steel on Monday, stopped work for inspection on Tuesday, poured on Wednesday and began framing on Thursday. Got in a few hours on Friday before big rain.

House slab rebar in foreground, entry slab behind.

Foam sealing around waste line punctures through 13" foam bed.

Concrete will fill up to top of verticle 2" foam.

First concrete being pumped from truck into same corner as above pic.

Half way- guys with rubber boots walk in 6" wet concrete to smooth out concrete.
After slab is finished, wood mudsills are set on top of a bed of roofing tar- this is the first step in air sealing the framing to the concrete slab.

Thursday morning. Earlier in the week, I had decided to not start framing until next Monday. I was hoping to get more information about the OVE framing from Katy, the engineer. I was hoping it would rain so we would not have to start. I was looking for any reason not to start. Truth is I was scared to start. All my training, classes, preparing, endless emails and meetings were over and now I had to actually begin to build the first new passive house in California. The burden was enormous and I was nervous and intimidated. I just needed a little more time.

Over tea and toast, I found my folly. I reviewed some PDFs on OVE and decided to cast my fear aside and just go for it. I dressed as if I were a soldier going off to battle. By the time I arrived at the job I was jubilant and cheering on the guys. “We are going to build a house today!”

Tilting up the first 2x6 wall section. The finished concrete slab is covered up with tarp and plywood scraps from another job. That green painting on tool shed/ office was a gift from Wild Carrots to 'Artisitify' the site.

This is a header for the living room wall window. It is composed of 2 1/2" of foam sandwiched between two 2x6s. It breaks tradition from "old school" headers in that it offers a thermal break in the wall assembly. A traditional 6"x6" solid wood header would have an R- value of approx R- 5.5 whereas this header has an R value of approx R-18. Our current building slogan is "less wood, more insulation".

South wall almost complete. Rain on finished concrete slab.

Happy Easter.......Terry