R-13 vs R-19? 15x30 ceiling

[JD3020]

Spending the rest of the winter in the shop turning wrenches, looking to spend a little time/money making it more comfortable to be in 40-50hr's a week. Specs on the garage is an older 15x30, 2 window's on each wall, and an overhead and man door on the north-facing wall. We've already replaced all the window's and man door, and i'm using wood shims as an amish version of green hinges. But its still difficult to maintain a constant temp, main source of heat is a wood stove and i've also got a 70k BTU diesel-radiant heater. It takes a constant hot fire to keep the shop at 70-75*, if the fire dies down it gets cold quick. Running the diesel heater is a pain as it gets HOT, but after its off for 15-20 minutes it gets cold again. Same with moving cold trucks/equipment in, takes a lot of heat to bring the temp back up. Just time consuming trying to keep it comfortable. Unfortunately theres no propane/natural gas to run a heater with a thermostat and keep life simple.

As far as we know there is no insulation in the walls(never opened the walls up), and i know theres nothing in the ceiling. Ceiling is just 2x4 trusses, 24" OC with drywall nailed on the bottom. Menards has faced R-13 3.6" thick in 32ft rolls for $17/roll, and 6.5" thick 39ft rolls for $27/roll. There is some plywood through the trusses for access and storage of light stuff(lights, truck mirrors, etc..) so we would have to compress the r-19 to fit down the middle, where the r-13 wouldn't be an issue. So should i keep it simple with R-13, or spend more $$$ and squish the R-19 under the plywood?

 

[The Cobbler]

that's lite for attic insulation . if you're going to do it, do at leastR-40 (IMO)
A contractor to do blown in is probably cheaper than you can buy the batts for . That's my experience anyway

 

[stm317]

Some insulation is always better than no insulation, but for a ceiling in Ohio, I'd want R40-ish or better. Especially if you're spending 40hrs/wk out there. Blown in cellulose is the most cost effective way to achieve that, and as The Cobbler suggested, you might be surprised by how economical it can be to have it done vs doing it yourself. The only potential issue that I see with that plan, is that you didn't mention any kind of vapor barrier, which you'll definitely want to avoid condensation/moisture issues. If there's already a vapor barrier in place, then never mind and insulate to your hearts content.

 

[Firebrick43]

Sort of torn here.

First this building will have low moisture loads. It's not a house that cooking, showers, and washing/dish machines are raising the humidity. Also the the wood stove is going to significantly dry the air out. Low amonts of insulation will keep the dew point outside instead of in it. I would say if done with r13 or r19 then a vapor barrier won't matter.

However 40-50 hours a week consistantly? If that's not a typo it would be benificial to go with higher amounts of insulation. As you exceed r32 a moisture barrier becomes more pertinent as the dew point moves into the insulation.

Some other thoughts is how big is the stove. You don't want to want to run a stove full bore all the time but you don't want to choke it off and have it smolder. To much insulation might mean a smaller stove.

I would suggest cellulose as well but if you were to use fiberglass I would pull up the ply storage floor. Lay down r13.

I would then lay 2x4 or 2x6 on edge perpendicular to the trusses to raise the storage floor up and allow a second layer of unfaced insulation perpendicular to the first.

If you do decide to use just r19 get a roll or two of r13 for under the storage platform. It does absolutely no good to compress fibererglass.

 

[kd3pc]

blown in R38-40+ and be done..for sure check the installers, as they are usually cheaper than batts. Even if you do it DIY, should not take more than a few hours to do the blown in.

 

[Showkey]

Blown insulation Menards R49 can be done for .56 per sqft if you DIY plus blower rental.

 

[Sovereign-1]

I just put in 46 bags of blow in cellulose in my attic. I put 7" over the attic and then topped up the rest house with a couple more inches since I had the machine. 7" gives me about R20 but I only use my heater a few hours a week and I too use my attic for storage so I upended studs along my walkways and then put plywood on top of that. The upended studs were used as my 7" measuring stick as well. Cellulose does settle a bit too. All of my storage is elevated so I only needed the studs for the walking areas.
Ironically enough I used the stuff posted right above me.
If you do DIY cellulose, its best to have a helper or two. I did all 46 bags alone and it took forever going back and forth.

 

[JD3020]

Main reason i wanted to do batts was so i could DIY it, but after reading some of these posts i checked and Home Depot rents a blower for $50/day, so i might as well do it myself. Is there is a brand/type of insulation i should use or stay away from? And i'm assuming i'll need a vapor barrier. We don't have any plumbing in the shop but we do pull our plow trucks in to thaw out as well as wet vehicles, so at times theres high moisture.

 

[BruceMc]

Regarding the dewpoint - moisture is going to condense out when it reaches that temperature, regardless of how much insulation you have. R13 or R60, you're still going to get condensation in the insulation without a VB. There's a temperature gradient within the wall and the closer you get to the outside, the colder it gets. Say you have an inside temp of 70º, an outside temp of 30º, and the dewpoint of the inside air is 45º, then at the point in the wall where it's 45º is where the moisture condenses out:


Inside 70º | _________ / 45º/ ____ |30º outside

Doesn't matter if the wall is 31/2" thick, or 30" thick.

 

[Dragfluid]

Blow in cellulose. Blow in 18" so when it settles, you'll have 16" for an R60. No reason to be chilly and uncomfortable, when the solution is so easy.

 

[tonyciambrone]

Keepin' the shop warmer than my house...

When I get moving and working in the shop even 50 degrees is plenty. This is also what Thinsulate lined jeans and wool socks were made for.

I agree with the blow in cellulose takes though

 

[Firebrick43]

Regarding the dewpoint - moisture is going to condense out when it reaches that temperature, regardless of how much insulation you have. R13 or R60, you're still going to get condensation in the insulation without a VB. There's a temperature gradient within the wall and the closer you get to the outside, the colder it gets. Say you have an inside temp of 70º, an outside temp of 30º, and the dewpoint of the inside air is 45º, then at the point in the wall where it's 45º is where the moisture condenses out:


Inside 70º | _________ / 45º/ ____ |30º outside

Doesn't matter if the wall is 31/2" thick, or 30" thick.

Alright, technically true. However in thin insulation(such as r13) enough heat is coming through the wall assembly and the dew point is extremely near the outside. Since it's close to the outside air currents from proper ventilation (and solar heat)quickly and effectively dry it out. As you get thicker and therefore less heat making it to the outside reaches of the insulation the dew point zone is moved further and further from the exterior. Now the condensation is forming further from the exterior of the insulation making saturation and it bad results much more likely. Heavy insulation makes vapor barriers much more critical.

Many older houses had r13 insulation in the wall a no moisture barrier. Actual performance is much lower due to thermal bridging. But few of these older homes had interior driven moisture issues due to the warm and leaky walls walls

As houses started insulating heavier thing have reared thir ugly head.

Now I am not saying the op should only insulate to r13. I am a super insulation proponent. But if your going to do r38+ its my opinion that a plastic vapor barrier is absolutely necessary. Because the op is burning wood ROI might be difficult at super levels however.

However it does sound like the ops drywall ceiling isn't finished. It's imperative that the joints be taped and mudded, all penetrations sealed, and painted. This will bring the drywall up to a class 3 vapor retarder. This will diffuse 100 hundred times (yes 100) less water compared to a 4x8 sheet with 1 square inch of air leakage such as unfinished joints, gaps around electrical boxes, and such.

 

[JD3020]

The ceiling is finished but rough. The recessed lights are original , and have gaps around them that need sealed. As for the attic there is no vapor barrier. Can't get pictures of the attic right now since I've got a truck in the way, but here's some quick pics of the shop.

 

[PT Doc]

Do it once. R 60. Done. Start saving bigger dollars right away compared to your initial plans.

 

[bobbyjean]

could you do the walls with the blown in ?