Adding More Attic Insulation
rochellej
| Posted in Energy Efficiency and Durability on
Hi I have a cottage from the early 70s. The owner did a pretty good job with vapour barrier fiberglass batt – 11 inches and air gap, from soffit which has vents along with two vent gables at either end of attic and vented roof peak (it is a new roof). Does it make sense to add more fiberglass batt to R50 or 60 in the main attic area though leaving an air gaps towards the edge. I am in Nova Scotia canada.
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Short of building a computer model and entering the data every answer you get is little more than a guess.
My gut says your doing a R25 upgrading to R60 assuming you will move in 12 years burning low cost fuel would be a poor financial decision.
To me it is a math equation that I do not have all the variables.
11 inches of fiberglass will be something like R22 to R29.
How long will you own this home?
How efficient is your furnace?
What is type and cost of your fuel?
What is your guess at the future cost of fuel 15 years from now?
Free modeling software
https://www.nrel.gov/buildings/beopt.html
Walta
Thanks Walta, I will do the insulation myself and 75% of the insulation material (I project around $1000) should be covered by rebates. 20 years in the home, electric baseboard but looking at installing a heat pump and some solar (also rebates available). I will check out the software. Thanks On another note looks like there is R10 batt in the walls with two layers of 1/4 of wood/vinyl paneling. Does it make sense to blow in cellulose from the inside or out in more batt.
Consider a pressure test and thermal scan before doing anything else. This will give you a good ides of the air barrier function. My house had 12" of fiberglass batts originally and I rolled them back and sealed all of the attic bypasses. I then added another R-60 blown on top of the original fiberglass. Additional work included some foundation insulation, additional air sealing of rim joists and a high efficiency (95%) gas furnace. These improvements cut the gas usage for this home from about 1,100 therms to 600 therms annually.
This work was done by me (except for the blown insulation) 15 years ago and has since paid for itself. A lot of gas has been saved and the comfort of the home was improved. If you can reduce your carbon footprint, go for it.
Thank you!