Wierd insulation question

[bmxdukie]

Hi folks. I have a wierd wierd insulation question.
In my 26 x32 detached garage I have 11' ceilings. Insulated and dry walled.
That said I have stairs up to a loft that is 32 x 12 wide.
I have insulation that is in batts that are in the 2x 10" floor joists ( truss manufacture called them storage truss)
If I was to blow in on the outside edges more insulation. And leave basically the center of the garage with batts (I think r 32 ) would it be cost effective or should I just leave it?

 

[atch]

From what I remember, if half of a wall or ceiling has one R value and the other half has another R value the unit as a whole has the average of the two R values. Or something close. This is based on what I was told when my work (back when I was young enough to have a job) built a building of concrete blocks. The cells in the block were filled with Styrofoam and the claimed R value for the assembly was something more than plain/empty concrete blocks and the R value of the Styrofoam.

So I think that adding additional insulation outside the storage will be effective.

This is only my opinion; I'm not qualified to perform any actual calculations for this.

And, b-t-w; since you're in the great frozen north I would think that you'd want all the insulation you can get.

ymmv

 

[blkhonda1991]

so you have an uninsulated attic but you have insulation at the ceiling level? only adding insulation at the edges would be a waste of money as the weak link will be the lesser insulation in the middle

 

[maxpat82]

I'm with blkhonda1991 on that.


you could remove your attic floor, put down 2" styro on the joist and put floor back right over it.

 

[ForceFed70]

No, you guys don't understand.

Basically what he's saying is that You can only fit 9.25 of insulation (2x10 bottom cord) in the part of the attic with the floor space. But your storage space/floor space isn't the entire size of the building, there's always space on either side that's not used and more insulation could be put there.

Sounds like he's got 9.25" of bat insulation across the entire attic. He's wondering if it would be worth it to place more/thicker insulation where there won't be a floor (insulation can extend above the bottom cord).

OP: That decision is up to you. 9.25" of insulation is R30 which is "OK". Generally speaking, most people go for R40 but it really depends on your heating and cooling needs. No point going crazy on the ceiling insulation if you're planning to use uninsulated overhead doors for example. When I was faced with the exact same problem, I choose to blow in additional insulation around the edges. But it was done as part of the initial insulation install. Not sure if I'd be motivated enough to go in after the fact and add more to the sides. Having said that - blow in insulation is an easy DIY job and the cost of the machine rental will often be waived if you purchase enough insulation at the same time.

 

[maxpat82]

I have the exact same configuration attic...but I insulated all around the attic with R40.


he is in ontario. unless it's a 1930 garage : he has insulated garage door..and if you plan to heat it ..well R30 isn't cutting it anymore.

the eastern end of canada doesn't really have the "smooth" weather of BC per say


the only way to add insulation in the 9,5" of space he have is to used a higher R value insulation (sprayed urethane $$$) or "lift" his floor the inches in need for the amount of insulation he wants.

my suggestion of adding styrofoam is just that.......considering you rarely put very heavy stuff in an attic

 

[K'ledgeBldr]

Hi folks. I have a wierd wierd insulation question.
In my 26 x32 detached garage I have 11' ceilings. Insulated and dry walled.
That said I have stairs up to a loft that is 32 x 12 wide.
I have insulation that is in batts that are in the 2x 10" floor joists ( truss manufacture called them storage truss)
If I was to blow in on the outside edges more insulation. And leave basically the center of the garage with batts (I think r 32 ) would it be cost effective or should I just leave it?

Any insulation you add is beneficial to a certain point- you still need to maintain ventilation.

How are the stairs configured? Are they enclosed/open? Is there a door at the top of the stairs? Or, are you referring to pulldown stairs? Do they have an insulated box over them?

 

[ForceFed70]

he is in ontario. unless it's a 1930 garage : he has insulated garage door..and if you plan to heat it ..well R30 isn't cutting it anymore.

There's nothing forcing an insulated overhead door in ontario, but I agree that an uninsulated door would be a poor choice and is unlikely.

R30 is perfectly adequate and appropriate for a shop that's occasionally heated and/or not heated to full room temp. I can only assume it met code requirements when installed. R20 was used up until the 60/70's in houses, and often not at all in garages. You'll note that I did say "most people shoot for R40".

BC gets plenty cold/hot, you've incorrectly assumed I live near the coast.

 

[bmxdukie]

Hi folks.. sorry was away on holidays..
It's a storage loft. Stairs are with an insulated hatch. I heat the garage and spent about 300 on propane this past winter. Just thinking for a few hundred bucks maybe I could recoup that and more over time.
I have drywalled the ceiling, insulated doors and brand new 3 years old build.