Our wonderful house got built! – GreenBuildingAdvisor

We finished our climate zone 6, 1200sf, Pretty Great House!

It was ready for our family of 8 to move in after less than four months of construction, the project came in right around budget, and after several years of significant housing instability, we are so grateful and hopeful than our symptoms of environmental illness and mold sensitivity will finally begin to abate.

Our team of builders was absolutely amazing, and we appreciated the additional help from this forum, along the books such as “Pretty Good House,” “Prescription for a Healthy House,” and “The Ultimate Guide to Building and Renovating with Nontoxic Materials”

Here’s a rundown on some of the many awesome features of our new home:

Wall Assemblies, approximately R30, from inside to outside: mineral/clay paint, sheetrock, 2×6” wall cavities filled with blown/dense pack cellulose, plywood sheathing, Adhero self-adhering WRB, 2” rock wool Comfortboard, 3/4” rain screen fully vented along top and bottom, James Hardie Plank siding.

Cathedral Vented Roof Assembly, approximately R60, from inside to outside: mineral/clay paint, sheetrock, service cavity created with furring strips, Intello vapor variable air barrier taped to the wall sheathing at the edges, 16” deep cavities created by I joists and filled with blown dense-pack cellulose, Mento vapor variable WRB, 2x4s installed parallel with the I joists to create a rain screen, plywood sheathing, ice and water shield, furring strips, metal roof.

Frost proof shallow foundation with curtain drains, 20mil Stego liner, Pro Clima liquid flashing to make air barrier continuous between the foundation and the Adhero.

I was our GC, an enormous learning curve for me, and there are many things I learned that most on this forum would know already…so I’m a good person for beginners to talk with! 🙂

During my exceedingly speedy housebuilding cram course last winter, I learned that designing and building a comfortable house that will not get (or at least be pretty super unlikely to develop) problematic levels of mold involves some obvious and some less (to me) obvious action steps:

Prevent bulk water intrusion, by installing roofs, siding, windows, doors, flashing, etc. properly.

Install rain screens behind your siding so that bulk water that makes it behind can drain and dry.

Keep materials dry during construction, and make sure that anything that does get wet (partially framed walls, etc.) has plenty of time to dry before enclosing.

Repair plumbing leaks immediately.

Make sure that insulation is adequate and very well-installed, with as few gaps as humanly possible. Reduce or eliminate thermal bridging wherever possible. Water always needs to be able to dry out.

Never make a “vapor sandwich” in your walls or roof (created when vapor-impermeable layers such as plastic are installed on either side of something like wood).

Prioritize air sealing: make sure the house is sealed as close to perfectly as possible, so that air can come and go only where you designate (i.e. through windows, doors, ventilation system).

A well insulated house shouldn’t have to deal with a large temperature change/increase in ambient humidity except around the change of seasons, and in theory, a properly sized continuous ventilation system like our HRV should also assist with this – not only is humid air constantly being extracted from the house, but the actual air movement is continual as well, reducing the risk of moisture accumulation/mold growth still further.

Another very important thing is to facilitate excellent drainage around and under the foundation, and not to rely only on vapor barriers that will fail in time. (I had no idea, but all basements and slabs and foundations must dry inward).

We wanted to reduce our mold risk by eliminating as many places within the walls and ceilings where a temperature differential could develop in proximity to materials that encourage condensation….and increase the ways that moisture can get out of the walls in the (certain) event it gets in. We chose Pro Clima’s special tapes and membranes because they are low toxicity and very effective, in our limited experience!

According to the experts with whom we consulted, houses don’t need to “breathe” – they need to be able to dry out. You don’t want drafts, except where you are controlling them.

We got very good numbers on our blower door test: 1.4 ach50 (even with an at-the-time poorly fitting vent fan cover that was more leaky than we wished; the numbers were .98 ach50 when my husband held the vent cover closed during the test).

A few of our home’s really luxurious and wonderful features:

– No spray foam used anywhere.

– The south wall has lots of windows to maximize passive solar gain (we will have a shade cloth arbor to keep the house cool in summer, along the entire south side).

– Our beautiful interior doors were made by friends (and our son!) out of solid pine – no foam!

– Incandescent lighting throughout.

– Ability to turn off electric power to lights/circuits at night with cut-off switches in each bedroom.

– Hardwired ethernet throughout the house.

– Restaurant Supply/stainless steel kitchen counters, sinks, and shelves.

– Brink whole house balanced Heat Recovery Ventilator designed (and then installed with great care and attention to detail by our builder) to run continuously, bringing fresh air in from outside which is warmed by (without mixing with) outgoing stale air. So, fresh air is always coming into the bedrooms, office, and living space, while being exhausted from the bathrooms, kitchen, and mechanical room. This is super fantastic!

– Woodstock Soapstone wood stove with catalytic converter (this is super awesome).

– Two capacious storage lofts.

– A fabulous mud room with tons of hooks and shelves for all 8 of us plus guests.

– Three bedrooms with big closets, plus a small office.

– Two bathrooms with amazing and awesomely wonderful warm water bidets. We found out about these because we once visited friends who have them in their bathrooms; we hearby invite all our friends, near and far, to visit us in western NY and experience such incredible appliances!

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A much more complete description of our summer of housebuilding can be found on my website (login with guest/guest as username and password to view): https://www.lifeisapalindrome.com/post/year-we-built-amazing-healthy-beautiful-house