Another insulation question.....

[rv245]

My head is hurting from reading all the insulation thread, so I guess I'll make it hurt a little more.

First a little info. This is my first really what I would call my own garage. It's a detached 24x40. I just bought the place in Feb of this year. Half the garage already had kraft faced insulation on the side walls (r-13) when I got it. Since then I did the remaining walls with krafted r-15. I just ordered my Berger Accuvent baffles to start on the ceiling shortly. I'm in zone 6 (Michigan) and want to get the right R amount for where I'm at. The trusses are 2x4's and 24" on center. I'm looking at the krafted 24" x 6 1/2" insulation with an R-19 value. I plan on using OSB for the walls and ceiling.

Here's where I'm lost

With krafted insulation will I still need a poly vapor barrier? Some say yes others say no.

Next question is that enough insulation or should I add an additional layer on top of the R-19?

I plan on heating the garage but it will not be 24/7 as this is at my cabin in northern MI. So basically just when I'm up there.

Last question or two. The gas meter is attached to the garage as it was built first before the cabin. I also have 30 amp service out there. If I decide on gas instead of electric should the gas piping be installed first before I button up the inside walls and ceiling? The biggest problem I have is that I have 3 separate garage doors, 2 on one side of the garage and 1 on the opposite side,o basically a drive though. So placement of the heater might be a problem.

Finally, I want to thank everyone on here as I've already learned a lot and got some great ideas. This is one of my favorite site to go to now. Thanks Again

 

[samert111]

I'm also in Michigan, Grand Rapids area. The R-15 is the best you can do in the walls but R-19 in the ceiling may be a little light depending on how efficiently you plan to heat the building. I ended up going with Kraft faced R30 because the ceilings in my building are 15' high and they came in 4ft lengths which were easier to handle working on a ladder up that high vs. a continuous roll. My building is 28' x 48' x 15' walls and I heat it with a Beacon Morris 75K BTU ceiling mounted furnace and it heats up very quickly. I have 6" walls so R19 there and the R30 in the ceiling and it never got below 40 degrees in the shop all winter with the heat off. Ceiling fans help keep the warm air off the ceiling.

With the Kraft facing you do not want the poly vapor barrier also. It would be considered a double vapor barrier and could cause condensation issues between the two. The Kraft facing is a vapor retarder, not as good as the poly for vapor control but it works OK for what your using it for. You could put up poly then your ceiling material (I used metal Durapanels) then blow in cellulose or fiberglass but you will need to get all your truss baffles in first and also block off the truss bays out into the soffit area so your insulation doesn't fall out into the soffits. Cost I think is about the same but the blown in would be far superior to the fiberglass batts because it fills in all the voids.

If you stick with the R19 in the ceiling, you could place another layer (Not Kraft faced) on top but I think if you check pricing you will find the blown in option just as price competitive and again far superior for heat retention.

I would rough in the gas piping before closing up the walls so you have the option of either gas or electric. You can always run additional gas piping inside to wherever you decide to place the heater.

 

[ForceFed70]

If you are putting OSB on the ceiling, then I'd strongly suggest you skip batt insulation completely and go with a blown-in insulation. The more you blow in, the higher the R value. I'd reccomend R40. Your local lowes or Home Depot will often give you a free insulation blower rental if you buy enough of the insulation.

Zone 6 - I'm not sure about the vapor barrier. Definately in zone 5. Might want to ask around locally for what the reccomendationa are. 6mil poly is typical.

 

[burleyfarm]

From Michigan also (Gaylord). Seems I remember a HVAC friend tell me you are not allowed to place gas lines in walls. They must be exposed except for when they pass through walls.

I'd place 6 or 9 inch faced batts in the ceiling then blow in what you need to achieve the R-Value you're looking for. This way you don't have to add a separate vapor barrier and the blown in fills in around your trusses and batt gaps.

I use an 80,000 btu radiant tube heater in my 30x34 garage. I have an 18x8 and two 9x8 insulated doors and it keeps things warm all winter. BTW I have r-19 in the walls with r-19 in the ceiling. I'm going to add enough blown in fiberglass this fall to get to an r-30+ for the ceiling. Mine is also drywalled. Without heat my garage stays in the mid 30's in the winter and very cool in the summer.

Good luck.

 

[rv245]

Thanks for all to comments and info so far.......

That's one of the reason's I though about R-19 as the trusses are only 2x4's. With the r-19 being 6 1/2" thick that would make it stick up about 3 " above the top of the bottom board of the trusses. I want to be able to have some kind of insulation on the on top of the trusses also.

How hard is it to do blown insulation in a garage with a ceiling already installed?

 

[stingry]

Thanks for all to comments and info so far.......

That's one of the reason's I though about R-19 as the trusses are only 2x4's. With the r-19 being 6 1/2" thick that would make it stick up about 3 " above the top of the bottom board of the trusses. I want to be able to have some kind of insulation on the on top of the trusses also.

How hard is it to do blown insulation in a garage with a ceiling already installed?[/QUOTE]

A lot easier than without the ceiling installed!! Sorry about that but couldn't resist! It's not hard as long as you have access to the attic. I like the AtticCat insulation. It is compacted into a small bale and requires a special blower to blow it into the attic space. Much easier than dumping bags into the blower. The blower will shoot the insulation 10-12 feet from the end of the hose. I got mine at Home Depot. The rental is free after you buy so many bags.

Cheers
Steve

 

[ForceFed70]

Blown in is very easy to do. You need 2 people - 1 to feed the machine(easy job - the wife could do it) the other the climb in the attic with the hose. I've done 3 different attics so far. The worst part is climbing in the attic and dealing with the dust (fiberglass blown in is much better for dust BTW).