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net zero | passive house, western maryland: coming to a close

We are thrilled at the success and completion of our first Foam-Free, (near) Net Zero, Passive House in Western Maryland.  The home is currently in the final stages of testing and certification and interior finishing. It has been an educational process with material usage, system selection and install, air sealing and insulation, window install and team collaboration.

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The views and placement of the house are extraordinary and achieve the homeowner’s goal of a comfortable, accessible, high performance home designed to view the meadow, marsh and forest.

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For more photos of the final walk-thru, visit the project page.

net zero | passive house, western maryland: sometimes its the little things….

like beautiful garage doors by Clopay to compliment the cedar porch…

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and clean, straight plumbing and condensation lines set against a backdrop of taped SIGA Majpell.

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net zero | passive house, western maryland: working outside while we still can

We now have our LP SmartSide up and looking more like a house, though we are hiding all of our fantastic details.  We have some warm and natural exterior colors waiting to be applied.

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The garage and shop have also been built and will be a nice bonus space to this Western Maryland cold, snowy climate.

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My favorite is the cedar porch.  The crew at Gosnell worked patiently with me to build what I had envisioned. It is thrilling to see in person and I’m looking forward to the final product with painted siding and stone porch.  The approach to the house is successfully comfortable and happy.

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net zero | passive house, western maryland: the views are revealed, window + door install

The large bird viewing windows have been covered with plywood for months as we await the delivery and install of our doors and windows.  The client chose INTUS uPVC windows for their performance, cost and manufacturer provided sill extensions.  The fact that the client could visit a local showroom and see these windows in person was also critical to their decision making.

Our window detail went through many rounds of design and mark-up between myself, Michael Hindle, CPHC and the team at Gosnell Builders.  The result is an air + water tight detail with little to no thermal bridging and over-insulating of the frame.  We also maintained our FOAM-FREE insulating details!

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Making the 2D line drawings translate into construction reality was not a problem with our eager construction crew.  Though labor intensive, the resulting air tightness and performance will be outstanding.

window installNot to mention the amazing views for bird watching!

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net zero | passive house, maryland: mento + furring

Upon hanging the TJI insulation cavity, the vapor open Weather Resistant Barrier (WRB) was installed and all seams were taped.  Given the pressure of the cellulose that will be blown-in behind this WRB, we decided to use Solitex Mento 1000 and taped with our favorite Tescon Vana tape.

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The next layer is the ventilation cavity / rainscreen / furring strips.  We decided on horizontal with vertical furring strips to keep the cellulose bulge in check and maintain an acceptable ventilation cavity as well as provide a more substantial nailing surface for our engineered wood siding.

net zero | passive house, maryland: hanging the TJI insulation cavity

We have built our structural 2×6 wall, installed and taped the plywood air barrier, and have created all of the window boxes.  It is now time to attach the 11 7/8″ vertical TJIs to our wall.  This TJI cavity will be filled with cellulose and serve as our main insulation layer in our Climate Zone 5 project location.  The TJIs are non-bearing and their vertical installation is addressed by Weyerhaeuser TrusJoist TB-821-2014 (comes up on a google search).

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Per the advisement of our structural engineer, in the areas where the TJI is not resting on the concrete foundation wall (with a bit of mineral wool sandwiched between), but is instead ‘floating’ we used a light 40 series joist hanger at the base of each TJI.  He also called for blocking top, bottom and mid-height.

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net zero | passive house, maryland : window install mock-up

Michael Hindle, CPHC, and I headed out to Western Maryland to review the window box and TJI insulating cavity mock-up.  It was cold and snowy.  Really cold.  I think I was the only one that noticed. The Gosnell crew is amazing, and, apparently impervious to freezing temperatures.

I said it was freezing, right? FYI, because of the freezing temperatures we chose to use tape for our water-tight detailing rather than a liquid applied product.  Once again, the Tescon Vana tape performed extremely well.  That stuff would stick snowflakes together.

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As shown in the photos above, every corner of the box is being taped as well as every edge of the window (allowing bottom free draining).  Our 11 7/8″ TJI wall is resting on the 4″ block ledge with a spacer of mineral wool sandwiched between the plywood base plate and the block.  The window box is a 5/8″ plywood box with a horizontal TJI top and bottom.

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Teamwork, Teamwork, Teamwork.  It is really a pleasure to watch these guys take pride in their work and listen to and learn new ways of building.  Peaceful implementation by the contractor is such a key factor to making these super-tight and efficient envelopes successful. Teamwork is always LESSON ONE.

 

net zero | passive house, maryland: blown away by the first blower door

The seams have been taped, the membranes have been sealed and not a creature was stirring.  We seized the moment to conduct our first blower door test and assess our Passive House progress.

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We are thrilled to report a .2158 ACH50 at this initial stage.  The results brought great pride to the guys at Gosnell Builders who are putting this thing together and shocked Mark Watkins, our Rater with his lowest number ever recorded.

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Thanks to our great team for working together and always being willing to learn some new tricks.

net zero | passive house, maryland: its all about the tape

Just in time for the holidays, our construction crew (Gosnell Builders) received a fine lesson in taping from Santa’s finest little taping elf (Michael Hindle, CPHC, Passive to Positive). Our elves were happy with the performance of both SIGA Wigluv and Tescon Vana tapes, which are being used over our primary plywood sheathing air barrier.

LESSONS LEARNED:

LESSON ONE:  Get in the field and see how planned methods work. Get your hands on the materials yourself to see that what you draw actually works. Or doesn’t.

michael taping

LESSON TWO:  With membranes and plastic sheets, corners matter. A lot.  Don’t just drape the membrane into an area with hopes that it will be sealed by the extra material.  Cut neat, flat areas in the field of an assembly, and bring them up to – but not over the corner – and tape it off.  Then tape a smaller, more manageable patch to fit into the corner.  Neatly fold the corners with sufficient, but not excessive overlap (it really is just like wrapping a gift).  Above may require a YouTube video of of above mentioned elf.

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LESSON THREE:  As defined in our Sequence of Operations, we installed our SIGA membrane over the top of the foundation wall and under the sill plate, to be taped to the exterior sheathing later.  When the guys were installing this membrane, they used a large strip with lots of over-lap. This made it hard during taping because where one sheet ended and another picked up, the overlaps were so excessive that it was very hard to know if you were getting a continuous taped seam.  Also the excess material flapped in the western breezes over the course of a month and was in less than pristine taping condition.  If we use this method again, we will stipulate that overlaps be no more than 6″ and only narrow strips of material be left “hanging out” and be taped down temporarily.

 

 

net zero | passive house, maryland: advanced framing + trusses

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And suddenly…it’s a house.  The trusses arrived and were set at 24″ on center on top of our 24″ on center 2×6 structural wall on top of our 24″ on center MSR 2×10 floor framing on top of our basement wall.  Walking through the skeleton to see the clean, aligned bones was really exciting.  Our framers did a fabulous job with advanced framing and aligning all the structure.  It sounds simple and straightforward, but I’ve walked in many that seem junked up with unnecessary studs and multiple upon multiple jacks and kings.

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The blue line along the top plate is Tescon Vana magic tape sealing the corner edge of our plywood air barrier. Each spliced top plate is taped as well.

Next comes the roof sheathing, finalizing the plywood air barrier and taping all the seams.

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8333 main street, 2nd floor · ellicott city, md 21043
410.313.8310 baltimore
washington