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SIGA Visit

One especially exciting construction shift was the day that Marc Coviello, a local SIGA rep, visited our site. He brought with him a wealth of building envelope knowledge and materials for us to use. SIGA, the company he represents, is a Swiss, high-tech envelope materials company that specializes in materials for high-efficiency buildings. Marc showed us some of the many products SIGA  produces, and how to apply them, and (very importantly) in what order. A few that we used were:

SIGA Majvest: This is the exterior membrane, which we applied by sticking it to the outside of the ZIP sheathing. It is a water resistive and air barrier: it's vapor-permeable so water from inside the walls can escape to outside, and is water resistant on the outside can't enter into it the opposite direction. Plus, this is a self-healing membrane, so all of the thousands of holes we're going to nail into it when we apply shingles won't pose moisture or air infiltration problems.

The exterior is wrapped in SIGA Majvest, which is self-adhering, with seams and corners sealed with SIGA Wigluv tape.

SIGA tapes: We used a number of different tapes in the membrane application and window and door installations to ensure continuity of the air and vapor barriers. They have tapes specialized for the interior, exterior, slab, and more.

taping
Sealing the window rough openings, and applying the tape in the correct order to avoid water inflitration.

SIGA Majrex: This is the interior air barrier that goes between the two layers of insulation on the walls and wraps up under the ceiling finishes. This helps keep the conditioned air in the house, and will hopefully seal off the initial leaks we found at the roof-wall interface. This is a smart membrane, meaning it can open and close in one direction. It's almost always closed, but when the conditions are right (a certain mix of humidity, moisture, and temperature), water vapor will escape out into the walls and ceiling (where it can escape to outside through the Majvest). However, it's always closed in the opposite direction, driving vapor to the exterior of the building.

The interior of the TRS is literally covered in SIGA Majrex, which is sandwiched between layers of wool insulation and taped with SIGA Rissan tape.

Marc recommended we do an experiment to see how well the Majrex works: we made two pockets of the material, one with the interior facing inside, and one with the interior side of the material facing out. Then we put a wet piece of wood in each, and sealed the edges with Rissan tape. After a few days of letting them air dry, we opened up the pockets to find that the wood in the backwards-facing envelope was still wet, but that the Majrex had allowed the water vapor to escape as the wood dried in the other one.

siga experiment
The results of the Majvest experiment: On the left is the envelope with the Majvest facing the correct way, and the wood that dried inside of it. On the right the is the envelope facing the backwards way, and the wood kept wet inside it for days.