Garage wall insulation

[garrett1812]

My home has a 2.5 car garage, with a 2 car portion under bedrooms, and a half car (6ftx20ft) bump out on the side. The two walls connected to the interior and the ceiling in the two car portion are already insulated and drywalled. I want to finish installation on the wall with the garage door and the half car bump out.

I primarily want the garage to be insulated to keep the bedrooms above warmer, and secondary to make the garage space more enjoyable in the winter.

Live in northwest Indiana, where we get plenty of cold and snowy days.

I know it will be important also to insulate the attic space about the half car bump out and the garage door.

On to my question: is there really a big difference between R-13 and R-15 insulation. Cost locally is around $0.25 and $0.40 per sq ft, respectively.

Thanks!

 

[LLLosingit]

My opinion is to go with the R13 and spend the money saved elsewhere. Does it have an insulated overhead door?

 

[larry4406]

Fur your 2x4 walls out to 2x6, add power to the walls, then go R21. That's what I'm doing.

 

[Notgrownup]

Little more insulation is worth it....get the most R value for your dollar.

 

[garrett1812]

So that is one vote for minimal insulation and minimal cost, one vote for maximum insulation and maximum cost. Any other opinions?

 

[buddyboy]

i'd go with the r-13

here is why

when you open your garage door in the winter you will dramatically change the temps inside your garage, any additional heat loss you prevented with the higher r value insulation will be lost at that point

install the r-13 properly, and caulk the rim and ceiling plates to stop drafts before drywalling

my attached garage is insulated the same as my house, insulated garage doors and rigid foam under the slab. very rarely does it get below freezing in the garage (on days when it's below zero) usually it stays around 35 all winter

i like to think my garage is capturing the heat loss from the house which lowers demand for the rooms next to the garage

 

[Falcon67]

R-13 will be fine, spend your time making sure it fits the cavities tight on all sides, top and bottom and is properly cut around and behind any objects in the wall. A little squish is OK, much better than ANY air gap. Slice and fit it around wiring, do not squeeze it behind any wiring runs.

 

[DC73]

Based on those prices, going to R15 will be a 15% improvement at a 60% increase in cost. That math doesn't fly with me. Obviously, the R13 is at a better price point.

Consider mineral wool instead of fiberglass. It's sound resistant, fire resistant, resists air movement through it and is just as easy to install as fiberglass. It also comes standard as an R15 batt (Lowe's carries the Roxul brand).

DC

 

[garrett1812]

I considered mineral wool also, but for R15 that was higher yet around $0.66/sqft (unfaced).

 

[MisterMike]

I'd seriously recommend looking at closed cell spray foam. We've used it in a couple of applications--a 48 x 30 pole shed and the walkout basement of our Wisconsin cabin--and it provides a phenomenal increase in the energy efficiency of a structure. Not only does it provide a high R-value per measure of thickness; it also acts as a vapor barrier and stops air infiltration dead in its tracks.

It's more expensive than other options, but it's far superior. Given the fact that you're not insulating a lot of square footage, it won't work out to a huge cost increase.

 

[Notgrownup]

I have R13 by the way...

 

[garrett1812]

R-13 is under $0.20/sqft at Menards sale starting tomorrow. My mind is made up.

 

[Notgrownup]

There you go....once you have it covered and you go in there in the winter, you will be able to feel the difference. I usually light my kerosene heater early when I want to work in there on cold days and it warms up quickly.

 

[James-W]

R-13 is under $0.20/sqft at Menards sale starting tomorrow. My mind is made up.

Since your mind is made up nothing I say now will matter. But I do think if you were to go with the spray foam you would be much happier in the long term, even though the initial cost would be much higher.