Meeting IBC R-38 Insulation Code in a Commercial Metal Building (College Station).
The City of College Station recently updated the IBC code. This update had some pretty substantial changes relating to commercial metal buildings; specifically the roof insulation (R-38). Under the old code an R-Value of 30 was required. This was easily achieved in the metal building by installing a 3” layer of standard insulation on top of the purlin followed by an additional 6” layer under the purlin. This code also allowed for insulation above the drop ceiling to count towards your total R-Value.
The new code would require a minimum 12” of fiberglass insulation to meet the R-38 requirement. This depth is not possible in a metal building using the industry standard 8” purlin & eave struts. The new code also requires that the roof insulation follow the envelope of the building continuously. This means that any insulation above a drop ceiling for example would not count toward your total R-Value.
Every City has interpreted this code differently and some have even adopted amendments to the code to circumvent this detail. Ultimately you need to be aware of this change because it will increase your total project cost. This code change could add as much as $5 per sq/ft (Dependent on installation technique). We are currently working with the City College Station to come up with the most cost effective solution to this problem. I intend to blog our results in an upcoming post.