80’s PINK insulation R value same as today?

[Crock]

Hello guys/gals

I have a question that I can not seem to find a answer to. I live in Ontario,Canada and our house was built in 1988. It is 2x4 construction and the garage attached to the house is insulated with Pink fiberglass (3.5 inch for 2x4 walls). Does anyone know if the R value of the insulation back then would be equal to the R value of current 2x4 rated insulation? Current Pink fiberglass is R12 and Rockwool is R14. Not sure if I am wasting time and must to switch it out.

 

[nafterclifen]

I don't know how 1988 insulation compares to 2021 insulation. I suspect you'd be wasting your time. I do know that you can get R15 for 2x4 walls, at least here in the states. Based upon the pricing on Home Depot's website, R15 (BF30) is 20% more than R13 (BF10).

https://www.homedepot.com/p/Owens-C...-Insulation-Batt-15-in-x-93-in-BF30/202585863

 

[Bert_]

If I was worried about it I would strap it and install foam board over the studs.

 

[The Cobbler]

in 1988 3-1/2" fibreglass was r-12

 

[rlitman]

in 1988 3-1/2" fibreglass was r-12

And it still is (unless it's a higher density material).

However, while the fiberglass itself doesn't really degrade over time, the R value of many insulations will.

In the case of fiberglass, the issue is air intrusion bringing in contamination. If the pink insulation still looks pink and fluffy, then it's probably still R12. If it's darkened by dirt (or even mold) that's been sucked through it, then it will be less than R12. This is one case where rockwool and cellulose beat fiberglass, because they're better at stopping airflow through it.

The same issue applies to open cell foam.

Now if you've got a modern "tight" structure with housewrap or the like, then these problems go away, since airflow through the insulation is prevented.

In the case of closed cell foam (of pretty much all types), there is a different issue with air migration. The blowing agent that inflates the cells increases the R valve. Over time, that gas escapes and is replaced by air (through the permeability of the cell walls). It takes years, but eventually, the R value will drop from the factory value.