Worth redoing r13 walls...

[Orionrising]

I have the wood shop part of my garage that will be heated. It has existing wall with r13... I need to add electrical so I could gut it and add a second layer of offset studs to bump it to about r30... Worth it in zone 4 climate? Ceiling is r60

 

[Orionrising]

Gah not used to tapa talk yet. Wrong subforum

 

[kd3pc]

the only way to increase the r13, assuming it is 2x4 construction, is to remove it and spray foam in the batt's place.

Your idea to sister in another 2x, 2x4 (I would sister in 2x6 if there is room) and triple the r13 with batts or better with spray in.

Spray is expensive and tough to update electric, etc later on, if you need to. Not sure the cost to upgrade would pay back in the long term, unless you use it a lot.

Fuel change may be more economical and just pour on the heat.

 

[Falcon67]

If your walls are well done, tight, no air movement I don't see the effort generating savings to offset the work.

 

[Orionrising]

It is on an 8 inch block perimeter so I could easily frame in an onset 2-6 wall. Just a question of economics wall is currently drywalled so fairly airtight. However the quality of the existing insulation is dubious from the areas of drywall I have pulled for other improvements
Currently heated with electric space heaters which are expensive kilowatts here

 

[theoldwizard1]

If you can replace the insulation "neatly", do so.

If your thinking of upgrading to improve heating/cooling efficiency, do the ceiling FIRST !

 

[pseudorealityx]

If you really wanted to calculate a payback... you would need to give dimensions, your fuel price, be it gas/electric/whatever, any doors/windows, etc.

IE, do a full heat load calc.


Based on the fact that you said, "Part of my garage..." I'm going to ASSume that this is a relatively small space and only have 2 exterior walls. If so, and you already have R60 at the ceiling, I would guess 'no'... this isn't going to pay you back in any short order.

 

[zmaxmotorsports]

How about just nailing/screwing 2x2s on the face of existing 2x4s ,that way its easier to insulate using the same stud spacing?
Youll just have to move the boxes out and wont have to change all the wiring in the walls.

 

[Spudland_Dave]

Howdy fellow western mainer...
To me...it would boil down to a couple things,

A) How much heating are we talking? In other words, you just want to keep it at 40 or so thru winter and jack it up a bit when your there? Or you looking for 70 degrees 24-7?

B) How cold was it there this past winter?

In my new, very tight (for a garage, if I got rid of my garage doors it would be tighter then a lot of homes) it usually hovers at around 38-42 with no heat at all...R19 in walls, R38 Ceiling. It got as cold as 28 in there towards the end of Feb...so for me to keep it 40, should be no big deal. I would say if your in that ballpark and are looking to do the same, I would doubt that going to R30 would pay back in any meaningful way.
My Dad's 28x44 has R13 walls all the way up north, he keeps it 40 as well with no issue. It certainly wouldn't pay to rip it out and redo...if you were having to buy all new insulation for some other reason, then yeah I would say why not...but I think you could use your saved money for other efficiencies, and save more money. I.E. Changing your heat source from electric to whatever liquid fuel you want would be a bigger savings in my mind...BUT it all depends on what your looking to do.

 

[jvitez]

Yes, do a proper heat load analysis and you'll get actual numbers.

My wild-a$$ guess is no, it won't make economic sense with a rapid pay back. But it could, if you plan on staying there for many years, want to keep using expensive electric heat, and are considering ripping out the drywall as you're questioning the quality of the insulation job currently present.

If the stud wall is OK and you remove bad insulation, I'd use Roxul in the 2x4 stud space and add 1.5 or 2 inches of EPS foam board over the studs, then drywall on top of the EPS. Check out building science as to what type and where vapour barriers are required for climate zone 4. XPS can act like a vapour barrier once it's at about 2" so you don't want that over top of a poly vapour barrier. EPS has no vapour barrier properties.

 

[Orionrising]

3 walls is the back 12 feet of a 24x 32 garage interior partition I did in 2-6r 23 roxul. Gets damn cold here 20 below is common and months at below freezing. Walls are currently not wired so have to open up or do conduit anyway.
Looking too keep it at about 50 to store paint and glue etc floor is r10 foam. Need to replace or make foam shutters for the two windows

 

[gnpenning]

you have 2 things your talking about here. One is upgrading and you ROI on it. The other is comfort.

It is a small area you are talking about. The investment to make it more comfortable would be worth it. What you found in previous checks tells you what you have is questionable. You have to open it up anyway to add power so why not??? Run extra for 240v and 120v so you won't have to do it again. Maybe water, air lines, speaker wires,etc.

Your doing it to make it so you can be comfortable in the winter. Do it or one of the other options.