Progress may seem frustratingly slow at this phase compared to when we were raising multiple walls in a work day, but this is certainly not due to lack of motivation on our part – it’s just the nature of this phase of the build. Now that we are working on the upper section of the building, we are using staging as a work platform. This means a lot of climbing up and down, bringing any tools and materials we need along with us (and hopefully not forgetting anything on the ground!).

We also continue to face the challenge of maintaining the continuity of the air barrier AND the ability of the house to be disassembled into two sections for transport. The finished HyggeHaus will have both an external air barrier (Solitex Mento 1000 House Wrap) and an internal air barrier (a layer of Intello Smart Membrane that will be applied upon completion of rough plumbing and electrical work.) One of the most important tools of the trade in this phase is surprisingly low-tech: the squeegee, a palm-sized square of plastic used to press down and smooth tape to get the best possible bond and seal with the substrate (the pressure activates the acrylic adhesive)..

On the lower section of the house, the Mento functions as the primary air barrier, due to the high likelihood of the Intello being compromised by occupant activities such as driving nails in the wall to hang pictures. On the upper section, the primary air barrier is the interior layer of Intello, which is applied to the underside of the roof trusses (see image below). This unusual arrangement allows us to avoid having to wrap the Mento up and over the top of the sheathing to join with the interior air barrier, and then setting the trusses on top of it (difficult and also highly likely to damage the Mento in the process). However, it does require an extra level of detail when sheathing the gable ends. A continuous bead of acoustic sealant is applied along the bottom chord of the truss to prevent air leakage between the truss and sheathing. Although the Mento is not needed as an air barrier above this level, we still applied it all the way up to the roof where it functions as the Drainage Plane protecting the sheathing and inboard wall assembly from bulk water.

At the joint between sections, the air barrier is split and taped to the sheathing on either side of the joint. This will be covered with a third piece of tape to provide continuity, and the joint will eventually be covered by a removable piece of trim backed with Gutex Multitherm insulation. When it’s time to move the house, the trim will be removed, the tape over the joint cut, and the LVLs unbolted. The house will then be disassembled into two parts, moved, and then reassembled in reverse order (applying a new piece of tape over the joint to maintain continuity.) The Intello will be detailed in a similar way.

We got our first chance to work with Intello this weekend while doing some preparations for rough plumbing installation. The rough plumbing phase will include installing the shower stall, which when installed will block access to the wall behind it. To prepare, we filled the stud bays with mineral wool insulation and applied a layer of Intello over the framing.

Up next: Rough plumbing, window installation, and applying outboard insulation (~3″ layer of Gutex Multitherm, a wood fiber board product treated with paraffin to resist moisture.) Onward!

This weekend the design build crew was very excited to walk on site to a raised roof! Kent and an East Branch Studio team set the front knee wall, followed by roof’s wooden trusses, which are anchored at ridge and eaves with 24 foot LVLs. Zip sheathing was then fastened to the trusses creating the roof deck and taped at the seams as further insurance against air leakage. The addition of the roof gives the structure a whole different feeling along with the added benefit of providing a dry space for work and storage.

The race to get the house “dried in” continued this weekend with more sheathing, Solitex Mento House Wrap, and Tescon Vanna Tape. We also prepared the window openings for window installation, adding window bucks that extend past the framing. This is necessary to accommodate the thick layer of outboard insulation and strapping which will provide attachment points for siding.

The addition of the roof reopened the debate over the possibility of adding a clerestory window. Meghan, an architecture grad student on our team, drew two options showing the clerestory window’s impact on the North and South Elevations which will be dependent on the final orientation of the building’s roof as will be determined by solar access at its final site (more on this in upcoming posts). The team felt this would break up the vertical shipped lap siding on the tall South Facade that is now quite prominent. Furthermore it would provide additional daylight to the interior and make the living room feel more open. With the knee wall in place, adding a window would have required modifying the existing framing. Also, the living room already has plenty of glazing area between the windows and doors; in light of this, we again decided against adding the window.

Now that the framing, sheathing, Weather Resistant Barrier (WRB) installation, air sealing, and window prep are nearly finished; the window and door installation is the next step on the critical path. This is a necessary prerequisite for rough electrical work, interior and exterior insulation and finish work, and ultimately, testing the building for airtightness. As the team works on wrapping up this phase of construction, we are enjoying watching the process of the Hygge House developing from an idea towards a finished product.

To make up for time lost to the predictably unpredictable New England weather, the HyggeHaus team held 3 build days over Spring Break week.

This week’s build focused on finishing interior framing, sheathing the lower section of the house, taping the CDX sheathing, prepping for roof and window installation, and installation and air sealing of a Weather Resistant Barrier (WRB).

Two ongoing design challenges for us as we wrap up the framing phase have been the interior loft layout and the question of installing a clerestory window near the high point of the shed roof to bring more daylight into the interior. Both aspects of the design are complicated by uncertainty over the final siting and orientation of the house, meaning we have to plan a design that can work for two opposite shed roof orientations. This is a challenge for the loft design, since the water heater we planned to install in the loft area must be located near the high point of the roof to have adequate clearance. We solved this by framing two access hatches into the loft and then laying the subfloor over both; this gives the option of installing the water heater on either side of the loft while maximizing available loft space, and the subfloor over the corresponding access hatch will be cut out to provide access to the space when the building reaches its final destination. We used the framed and decked loft as a working platform to prep for the roof installation.

The shed roof’s structural components will be wooden trusses, which will rest on a short knee wall of 2x6s with an LVL bottom plate at the peak, and directly on an LVL plate at its low point. The LVL plates will provide added strength and stiffness to the roof assembly when the building is disassembled into separate roof and body sections for transport. The lower LVL plate rest on top of the lower wall’s LVL top plates; both extend past the plane of the walls on the interior to provide an attachment point where the two sections of the house will be bolted together. The idea of adding a clerestory window to the upper section of wall below the roof was challenged by the difficulty of finding a location that would still work if the roof was rotated 180 degrees. Eventually, we decided that the existing windows and doors would provide enough natural light that the clerestory window idea wasn’t worth pursuing further. 

Our short-term goal is to get the house “dried in” as soon as possible; to that end, part of the team devoted a significant chunk of time to prepping windows for installation. Our collection of 7 donated windows got a fresh coat (or 3) of black paint, to harmonize with the warm gray paint color we picked for the siding. The WRB membrane we used was Solitex Mento 100. This durable, fabric-like product which was detailed with both Tescon Vanna and Ectoseal Encors. When details with the window and door connections are completed the entirety will act as the primary air barrier, preventing air leakage through the building envelope and the accompanying unwanted heat gain/loss., reducing the chance of condensation within the wall assembly, and is the drainage plane for the vertical surfaces of the building.

To work effectively, this weather resistant barrier must be detailed properly; this includes allowing sufficient overlap between courses, lapping to the weather, minimizing stapling in the field (creates holes), avoiding bunching or wrinkling of the membrane, and taping at joints. The taping process, as we found out, has its own learning curve. The challenge is to apply the tape without wrinkling it, wandering off the line, or having the tape stick to itself — easier said than done! But for the purpose of building a high-performance home, every minute we spend getting these details right really does make a difference.