The Inside Outside Guys: Attic Fans: Insulated Siding Systems Continue to Evolve

By Ken Calverley and Chuck Breidenstein

DETROIT, May 19, 2022
~ It was going to be the siding product of the future for housing.

The commercial side of the construction industry had discovered it years before and embraced the design flexibility and thermal insulation properties it offered.

But during the housing boom of the 1990s, a few large builders embraced the technology as a cost-cutting strategy rather than a value enhancement and created a stigma that some markets still battle today.

The product is popularly known as EIFS, or exterior insulation and finish systems. It can provide a monolithic finish in virtually any color, but like any siding system, it demands attention to good mechanical flashings around all penetrations, from windows and doors to exhaust vents.

Laypeople look at the finish and call it “stucco,” and it does mimic the product used for centuries over masonry exterior walls. Builders look at the finish and call it Dryvit, the patented “Kleenex” name in the industry for this type of system.

Decades ago, we knew there was an issue with the typical wood framing system we had been using.

Predictions of global cooling forced us to look at where heat was “lost” through the thermal envelope of our structures. A major component of that envelope is the exterior walls and everywhere in that wall frame we had a piece of wood, we created what we call a thermal bridge where heat could easily move from the warm interior to the cold outdoors.

This is often evidenced in older homes by the appearance of dark shadowing on the walls and ceilings where there is a stud or a rafter.

The US Department of Energy declared the answer was continuous insulation over the exterior wall frame, so we began sheathing the frame in rigid foam which effectively slowed the thermal bridging.

But this occurred at a time when we were discovering vinyl siding products as well as using dark-color aluminum siding products.

Expansion and contraction of these products against the foam during high sun exposure created a noisy home similar to the sound of fingernails on a chalkboard.

Additionally, it was recognized that someone with a sharp razor knife could cut their way into a vinyl-sided, foam sheathed, house in minutes.

During this time, the industry was also discovering house wraps; woven fabric installed over the sheathing that was intended to seal the home against air infiltration around gaps and cracks.

Through trial and error, the industry saw the re-engineered version of this product as a rain barrier on the outside and a permeable membrane from the inside-out that allowed moisture in the wall to move to the outside.

EIFS seemed the perfect way to blend such new products with new concerns. The base system uses rigid foam over the wall frame, a rain barrier wrap, metal or woven lath and a synthetic stucco applied as the exterior finish.

Typical stucco consists of sand, cement and lime mixed with water. Synthetic stuccos will have acrylics and other additives that give the cured finish more desirable properties like reduced shrinkage during cure and resistance to cracking from structural movement and climate issues.

The residential housing sector is once again embracing the use of EIFS, whether as a whole-house exterior finishing system, or as an accent on one floor only.

Sub-contract specialists can be trusted to professionally install the product to provide decades of service.

And if a situation should arise where the surface is breached, whether from an aggressive woodpecker or a fallen tree branch, one of our experts can help make the repair.

Mark Mercier, owner of Rhino Shield of Michigan in Brighton, can repair the system and even enhance it with the application of a ceramic coating.

It is also suggested that any homebuyer looking to purchase a property with an older EIFS siding should retain a qualified property inspector to examine the system for any possible leaks.

EIFS might be part of the solution to providing energy efficient housing but, like any specialized system, it requires the talents of a professional like those you’ll find at InsideOutsideGuys.com.

For housing advice and more, listen to the Inside Outside Guys every Saturday and Sunday on 760 WJR, from 10 a.m. to noon or contact us at InsideOutsideGuys.com.

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