designing a wall assembly

[civeng800]

Let's compare the following two wall assemblies listed from exterior to interior: 1. concrete, insulation, and gypsum board and 2.stucco, insulation, and concrete. Therefore, in case one, the insulation is inside, and in case two, the insulation is outside. Case one is good because the insulation may not fall where the dew point temperature is. Case two is good because the concrete is not exposed to freeze-thaw conditions. So, which is the more practical wall assembly to use?

 

[ishvaaag]

1 is best because gypsum is not at all good for any exposition to humidity or water, which will take from its outer placement.

 

[Focht3]

The answer to your question is, "It depends." The first option will work in most, if not all, climates - but isn't particularly attractive (unless a brick veneer or other surface treatment is used.) Stucco allows a lot of possibilities from a cosmetic point of view, but may not work well in cold climates when the insulation layer is compromised by moisture. And a stucco finish, if done poorly or mated with the wrong materials, can fail miserably.

Each structure has to be evaluated on a case-by-case basis -



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[RegisPreact]

In the USA there is an abundance of gypsum so we have always addressed this building material instead of what the rest of the world can manage with. I am aware of a product import from China that replaces the gypsum complete with multiple freeze thaw cycles, water resistant and mold resistant. I am sure they have not passed UL specifically, but they have passed the same tests with another laboratory and did receive New York City's MEA so they are being used in NYC. So, the limitation of the gypsum may some day be as much a memory as the pollution from coal burning heating fires in London....

 

[jheidt2543]

Option 1 provides the most durable exterior to the building and can be have a variety of good looking finishes with the use of form liners. It may also be the least expensive, if you compare the cost of a form liner with the cost of EIFS. I have built a number of buildings like this using cast-in-place and precast concrete.

Option 2 allows you to add color to the exterior. However, it is not as durable as the concrete when it comes to vandals and weather. It also is very dependant on correctly installing the detail accessories like flashing and caulking.

In the end, it is a matter of architectural tast. I happen to like the variety of cast-in-place concrete with form liners.