What is R-value of Barndominium Insulation?

R-value measures the resistance of insulation material. In barndominium, insulation is crucial as it provides safeguards from heat & cold sensitivity. Understanding the R-value would help in understanding the requirements set by the authority.

Building a barndominium would need approval from the local authority which also affects in raising a loan or arranging the steel kit supplier. Most importantly, the designs and the approvals from the authority would have the insulation information (measured in R-value).

What does the R-value mean?

A higher R-value means a better insulation capacity. So, you first need to check what is the required R-value as per your barndominium’s location and climate.

Let’s say, your barndominium is located in a cold region where temperature deviates too quickly and it gets worse during the winter. And, as per the local authority, the required R-value of the insulation material would have to be R-35. (R-30 represents that the heat would not go outside even within the extremely cold season).

Now, you need to find out how can you make R-35?

Let’s imagine, that you have 5 insulation choices and you decide either to go with batt insulation or spray foam insulation.

Your next task is to find what is the R-value per inch that the insulation material is offering.

For the batt insulation, you may get R-3.00 to 3.8 per inch which would need you to install at least 11-12 inches of insulation.

Alternatively, you may install the spray foam insulation which offers a higher R-value (more resistance) compared to the batt insulation.

We cannot exactly tell a single-digit R-value since it varies depending on the material. For example, the batt or blanket insulation can be made with either fiberglass or mineral wool and in both cases, the R-value would be different.

R-value of different insulation types

Below are the R-value of different insulation types you may consider for your barndominium. Please note that the actual R-value may differ depending on the product supplier & their respective quality.

1. Fiberglass (batt): R-2.9 to R-3.8 per inch
2. Fiberglass (blown-in): R-2.2 to R-2.9 per inch
3. Rockwool (batt): R-3.3 to R-3.5 per inch
4. Rockwool (blown-in): R-3.1 to R-3.3 per inch
5. Cellulose (blown-in): R-3.1 to R-3.8 per inch
6. Expanded Polystyrene (EPS): R-3.6 to R-4.2 per inch
7. Extruded Polystyrene (XPS): R-4.5 to R-5 per inch
8. Polyisocyanurate (Polyiso): R-5.6 to R-8 per inch
9. Closed-cell Spray Foam: R-5 to R-6.5 per inch
10. Open-cell Spray Foam: R-3.5 to R-3.7 per inch

Why does spray foam give a max R-value?

Spray foam gives better coverage compared to other types of insulation. For instance, a batt fiberglass insulation would come in pieces and you need to attach it. For the blown-in insulation, you will blow the cellulose in the wall and they will set over time.

However, the spray foam expands after spraying, leaving no blank spaces or gaps within the wall. Moreover, it offers a maximum moisture barrier which eventually strengthens the insulation over time.

R-value vs U-value

Both the U-value and the R-value measure the effectiveness of insulation material but for the insulation of different places.

The R-value provides a measurement of thermal resistance. For example, it tells how effectively the insulation will keep the inside heat and block the outdoor cold.

Alternatively, a U-value would measure the thermal transmittance of heat transfer through a structure. For instance, it measures the possibility of heat loss through windows, doors roofs etc.

In simple terms, the wall’s heat resistance is measured with the R-value, and the Door/window’s heat loss is measured by the U-value.

Both the R-value and the U-values are useful especially if you are building a metal barndominium in an area where temperature deviates heavily once in a year.