Major Wall Types: Institutional, Commercial, and Residential
This blog accompanies 1-2 minute videos (7-10) of www.GreenBuildingSolutions.org’s new educational videos. They present Joseph Lstiburek, Ph.D., P.Eng, ASHRAE Fellow of BuildingScience.com, an international expert in building science. Videos are here.
The wall that provides an efficient level of insulation regardless of external climate, exists in three different major wall types. They are the institutional wall, the commercial wall and the residential wall. These three different designs offer optimized thermodynamic potential in almost any climate. We mean, within subarctic, very cold, cold, hot-dry, hot-humid and other types of challenging insulation-necessary climates.
The Institutional Wall
Architects and designers exaggerate specifying the institutional wall as “the 500 year wall” because of its durability. Rock or concrete masonry provides the structure, with water, air, vapor, and thermal control layers outside that surface. It has a gypsum board interior and dries from the control layers out and from the control layers in, giving it moisture adaption capabilities to exist in multiple climates. Builders don’t usually build a wall to last hundreds of years, or last generations. And, they say it would take that long to pay for it. (See 1:11 video The “Perfect” Wall Part 7 – The Institutional Wall)
The Commercial Wall
The commercial wall is the second of the three major wall types; a variation on what we call conceptually, “the perfect wall”. It trades out masonry for steel studs. Like the institutional wall, architects line the interior with gypsum board. Its interior steel stud cavity doesn’t contain much if any, insulation. However, because this wall uses steel, a thermal conductor, energy transfer across the structure from outside to inside the framing is very high, making it almost impossible to control wall temperature through cavity insulation anyway.
Therefore, this wall uses control layers on the outside of its structure. To deal with steel framing, designers can insulate the wall on the exterior with continuous insulation to help prevent heat and cold from reaching the framing. Insulation added to a steel wall cavity reduces sound transfer.
The Residential Wall
The final variation of the three major wall types is a residential option which can utilize many insulated substances for its interior cavity. Fiberglass, cellulose, foam, polystyrene – the options for insulation of a residential wall are extensive as the configuration of the control layers is what matters most. Sheathing (particle board, wood, fiberboard, foam board, etc.) appears outside the framing first. This wall will dry from the sheathing out and from the sheathing in. The vapor, moisture, air leakage, control layers are outside the sheathing in proper order. (See 1:12 video The “Perfect” Wall Part 10 – The Residential Wall)