WRBs: SIGA Majvest vs Pro Clima Adhero
xenomorph
| Posted in Green Products and Materials on
First post on GBA, have learned a lot reading the comments here.
I am designing a CLT structure and I want to install a self-adhered WRB over the entire exterior surface (walls and roof, and wrapped into window and door openings), then install rigid insulation outside of that, with a rainscreen over the insulation.
Other than a lower price for the Adhero, is there any substantive difference between these two products? Are there others that I should consider?
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Replies
Hi Alex,
I'm going to give your question a bump in hopes that a builder or designer with knowledge of both WRBs will chime in. Matt O’Malia of GO Logic used Pro Clima’s Solitex Adhero on this CLT project. I know he was very happy with the product. He might be a good person to ask—he’s very approachable and a wealth of knowledge.
+1 Also build a house with that same building enclosure and wondering what/how many membranes to adopt.
Majvest is a family of products. 500 SA may be the most comparable to Solitex Adhero. I've not used either, but I have used Henry Blueskin VP100 which is another comparable to spare none on decision fatigue. Self-adhered membranes give awesome performance if the budget can accommodate.
Assuming the membrane gets covered up within a week of installation (e.g. by cladding), can you give a comparison of the relative pros and cons of mechanically fastened & taped vs self-adhered?
I recently did some research on this and discovered that the main difference is that Majvest is a microporous membrane and Adhero is a monolithic one.
This is from the manufacturer of monolithic membranes so it will be biased, but it's the most concise summary I can find of the differences: https://hpp.arkema.com/en/markets-and-applications/chemical-industry-and-general-industry/breathable-films/
I'm not totally sure which is better. Intuitively it seems like monolithic membranes would be more resistant to hydrostatic pressure.
Here's a quote from a salesperson in a GBA article:
"“With traditional housewraps,” explains Ken Levenson of 475, “the vapor permeance is from the microscopic tears in the woven membrane, which the vapor can push through; while with a monolithic membrane with no tears or pores, it is the actual molecular structure that is transporting the vapor.” As such, because traditional wraps resist vapor diffusion at lower pressures, there is greater chance of moisture build-up filling the pores which can block vapor movement, while the molecular structure of the monolithic membrane moves the vapor at very low vapor pressure differentials, avoiding the danger of blockage.
Also, the membrane’s performance will not degrade from surfactants in cedar siding, according to Levenson."
https://www.greenbuildingadvisor.com/article/whats-new-with-water-resistive-barriers