ENERTIA   HOMES No Fuel? No Power? .......No Problem
Since the outbreak of tornados starting April 14th 2011 the most recurring question in our emails has been: Will an Enertia Home stand up in a tornado? Everyone who follows Enertia knows our solid Gluelam walls are already leagues ahead of conventional stick houses. The after-storm photos, on every TV screen and magazine page, show clearly stick frame components, siding, sheetrock, and fiberglas, strewn for miles- in fact it has a name: “debris field.” Enertians suspect, rightly so, that with our solid Gluelam wall system it doesn’t have to be this way. They just want to know how far we can take it.

One thing is for sure. It is not possible to build a “tornado-safe home” with conventional stick framing, and no less than the National Weather Service will tell you so. While most of the world rates tornados on the “Fujita Scale” the NOAA weather agency rates US tornados on the “EF Scale” which is based on the predictable failure sequence of conventional stick frame houses!

Now that plywood (laminated wood !) has given way to flake-board, and particle board- there is nothing in a conventional stick frame house that has any substance whatever.
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EF 0

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EF 2

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EF 1

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EF 3

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EF 5

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EF 4

But it is possible, using modern gluelams and engineering, to build a “Tornado-Safe” home. One where the structure remains standing and is not cracked or racked to a point beyond where the windows and roof coverings can be replaced and the original structure returned to its original appearance and use. A structure that will not cave in on you and your possessions, or be picked up and scattered for miles upwind.

And it does not necessarily involve a lot of extra costs- you must simply make the decision to build differently, with a non-typical material, in a non-typical way. Your house does not have to look any different- but being built with solid gluelam walls it is monolithic yet resilient, and the structure will likely still be there after the storm- minus any decorative items you have attached to it with nails and staples. Nails and staples are the only thing supposedly holding the rest of the houses in your neighborhood together.

The answer comes from understanding tornados. Like understanding nature led to the original Enertia® energy-storing house design. In fact, understanding tornados could even lead to a source of power.

Tornado (and similarly hurricane) damage comes from three sources. The wind itself, the grinding and impact action of the debris in the wind, and the atmospheric pressure change.
WIND. Despite the name “twister” the structure only sees straight-line wind during the 4-10 seconds of critical impact. In a conventional frame home this wind first deforms and then breaks the connections in the wall. But in a “Monolithic” wall , like the Gluelam walls we use, this pressure is turned into an “overturning force” as it tries to pop the entire monolithic structure out of the ground. So once we have a structure able to take more than the 120 mph winds that destroy stick-frames, the key to further survival is to prevent up lift.... prevent popping the structure out of the ground like a carrot.
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DEBRIS. Unless you are the first in line, the tornado has picked up bricks and debris from earlier frame houses in its path. These impact your wall at the full wind speed of the cyclone. Whether your wall will take it depends on “resilience” a property of adsorbing energy and actually redirecting debris back with spring-like action. Unlike brick and concrete, which are brittle and crack, the gluelam wall has energy-absorbing spring as demonstrated in the Texas Tech air-gun impact tests. In fact, most commercial and competition diving boards are made of laminated wood, because of this “spring.”
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BAROMETRIC PRESSURE: When the tornado crosses your house a zone of low barometric pressure engulfs it. If the wind breeches the wall an area of high pressure develops inside it. Frame houses simply explode. The modern tendency to make frame houses tighter and tighter for energy efficiency only makes this worse. In Enertia gluelam structures the walls are able to take these pressure differences, and if it is double-shell, like most Enertia structures, the “envelope” around the inner shell relieves the pressure and takes the impact of what is almost an internal “sonic boom.”
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Back to the question- Will an Enertia Home stand up to the tornado? That a standard out-of-the box gluelam Enertia home will do better than a stick frame- is obvious. But gluelam construction goes beyond that...
WIND. The single 4 layer gluelam that Enertia uses, with the standard screw pattern, is designed to tolerate and survive 140 mph winds. But the North wall in a double shell Enertia Home is two gluelam walls, 8 to 12 inches apart, reinforced with vertical gluelam buttresses and steel ties between the two walls. Effectively, this reacts as a 20 to 24 inch thick wall, and serves as an “anchor” to the rest of the building. As do all the intersecting gluelam walls. Some Enertia homes have doubled end walls too. And the corner intersection between two double walls, at 90 degrees, is especially strong. These doubled end walls are now mostly sent to cold climates, but you can order them for your “tornado alley” location as well. If all four walls are doubled, and ties from the footer to the roof are installed in these cavities, the home can be designed for up to 300 mph, F-5 tornados.
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DEBRIS. Debris comes from brick veneer and siding being sucked off a stick frame house. There is no siding on an Enertia house- the outer lamination of the Gluelam is the siding and it is not attached by nails or staples, it is a part of the gluelam. Tests have shown that the glue is stronger than the wood itself. The gluelam wall acts like an energy-absorbing spring and will deflect debris- although the surface will be sand-blasted and indented, it’s only cosmetic and does not affect the strength of the wall.
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PRESSURE. The Enertia house has a small second atmosphere inside the outer gluelam shell to absorb the pressure-shock of a tornado. If the fourth wall is a south-facing glass wall, as in the solar versions of the Enertia Home, you will lose the glass- but in so doing you will save the structure.
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There is a big difference between whether your house will take the tornado and remain standing, and if it will take the tornado, remain standing, and be re-conditionable to safely move back into. This is why log houses have always been favored in earthquake areas. Concrete and steel houses survive the quake, but they are brittle and crack, or bend and deform, and have to be demolished and rebuilt. The log houses simply spring back, and the owner can move back in.
And that is the key- the Enertia building is monolithic but flexible. Monolithic and brittle (as in a concrete structure) may stand, but after the storm it will have to be demolished and rebuilt. Gluelams have ‘spring’, and even if the building is torqued by up to 5 degrees, it can still be pulled back with the hydraulic rams typically used in the house-moving trade.

Upgrading the tornado resistance of your Enertia Home to F-4 or F-5 is not difficult. In fact much of it is the same upgrade that we use for earthquake areas like California. Just tell our designers this is what you want. These upgrades are typically not visible like granite countertops or Jacuzzi tubs, and you may need the courage of your convictions to order them. The structure needs to be respected in the beginning-the granite and water features can be added later.

Tornados are not the Wrath-of-Nature. They are a scientifically understandable phenomena. Do you want an Enertia Home that will withstand up to an F-5 tornado? Check out our Tornado-Safe Page. Furthermore, we will guarantee it.