Stop the largest losses leaks first.
Cheapest insulation per r value.
But with that said here are some general guidelines.
Rosato asbestos insulation is the most authoritative source on asbestos properties and gives data for the thermal conductivity of asbestos in different forms and with varying temperatures for magnesia asbestos insulation at mean temperatures ranging from 100 f to 400 f the k value thermal.
Opt for the closed cell variety if you need an air barrier vapor barrier and efficient insulation in the least amount of space possible.
Open cell spray foam is rated at about r 3 5 per inch while closed cell spray foam is much more efficient at r 6 0 to r 6 5 per inch.
These can be combined for best insulation quality.
Expanded polystyrene foam eps is the cheapest and least used foam board product on the market.
Denim is also available in a loose fill insulation.
The way a home or business building is insulated has a huge impact on the heat loss gain.
The best places to insulate will always be the areas where the most heat per square foot is leaving in the heating season or entering in the cooling season.
Denim insulation costs anywhere from 20 percent more to three times the cost of other insulators for the same r value.
Home depot sells a roll of 16 inch by 48 inch denim batt for 11 20.
Products with a higher r value have a higher cost but have an increased capacity to resist heat flow and therefore provide greater insulation.
Standard fiberglass blanket insulation adds between 3 2 to 3 4 r per inch.
Each type comes with unique advantages.
3 1 2 insulation r 11 5 1 2 r 19 etc.
Also called styrofoam insulation this is the least expensive material.
We don t know what you have now r value or type.
This product typically has an r value of 3 6 to 4 0 per inch of thickness.
Here are some currently available high r building insulation products as well as some specialty very high r insulation materials.
For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3.
That would be a helpful factor in determining how much more you should add.
Aerogel has an r value of about r 10 per inch is 99 air and insulates up to 37 times higher r value than fiberglass.
The material is costly and fragile factors that have limited its use in residential construction.
Consider spray foam anywhere you need an air barrier as well as insulation.
It has an r value of 6 7 and covers 5 3 square feet.
These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.
In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and an inch of blown cellulose in an attic has an r value of 3 2 3 7.
Notes to the table above.
Notes on the r value k values of different forms of asbestos.
Best insulation r value per dollar.
For example a wall with 3 fiberglass batting r value of 10 8.