R-30 Insulation And Heat Absorbtion

Ask The Expert – Q & ACategory: QuestionsR-30 Insulation And Heat Absorbtion
RIMA Expert Staff asked 5 months ago

How long does it take a layer of R-30 fiberglass (or cellulose) insulation to become saturated with heat so that it begins transferring the heat?

1 Answers
Best Answer
RIMA Expert Staff answered 5 months ago

At the risk of sounding flippant, how high is up? The amount of time it takes heat to penetrate R-30 of mass insulation depends upon several factors, principally the temperatures involved and the amount of convection air that surrounds the mass.
In the test to determine the R-value of the material, the mass is placed between 2 surfaces — one hot, one cold (i.e. 100 degrees, the other 25 degrees) so that there is a 75-degree difference between the 2. After about 1 hour the material reaches a steady state temperature and the calculation is made.
Once the same material is installed in a building everything changes — temperatures, air spaces, convection and radiation, so the R-value and time required to reach steady state is not testable.
Hope this answers your question.