How Much Roof Insulation Is Enough

I suggest a 4 5 10 30 60 rule.

How much roof insulation is enough.

How well a particular insulation works is expressed by the r value which ranges from 2 0 to 8 0 per inch of insulation. Add insulation to attic. Input length and width of area to be insulated. For these locations i recommend intermediate insulation values between those for cold climates and hot climates.

If you need to add four inches approximately r23 with polyiso insulation or r15 with expanded poly styrene there may not be enough room between the membrane at the roof penetrations. R 4 windows r 5 under slabs r 10 foundation walls or slab perimeter r 30 above grade walls and r 60 in the attic or roof. Click the button to calculate the amount of insulation in square feet and man hours wall and ceiling fiberglass insulation needed for this job. As a general rule the attic needs to have 12 inches of insulation warner said.

This calculator is to be used as an estimating tool only. What about existing houses. Where you live different climates require different insulation r values. The higher the r value the better job the insulation does at preventing the transfer of heat.

That s my rule of thumb in any climate zone if you have a crawlspace or unheated basement make sure there is insulation between the floor joists. Existing 3 4 inches of insulation. I suggest a 4 5 10 30 60 rule. You will need a higher r value of insulation if you live in the northeast than if you live in southern california.

R 4 windows r 5 under slabs r 10 foundation walls or slab perimeter r 30 above grade walls and r 60 in the attic or roof. The amount of insulation recommended for your home will vary depending on a number of factors. For these locations i recommend intermediate insulation values between those for cold climates and hot climates. Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam.

Having enough insulation in your attic is one of the best ways to save energy on both heating and cooling your home. Have loose fill insulation blown in on top of existing insulation. Membrane manufacturers as well as various building codes require 8 inches of space from the flat roof membrane up to a penetration.