Faced or Un-faced Insulation?

[Dominico]

I need to insulate the finished ceiling of my 24 x 26 detached garage with either faced or un-faced insulation (do not like blown insulation). I have easy access to the attic therefore I will just lay the rolled batts between the joists. I have a ridge vent however think I need to add a couple more soffit vents as I only have two on each side (2' overhang).

I occasional heat the garage with a space heater in the winter months however my main reason for insulating is to block the summer heat transfer from roof to garage (below). Should I use faced or un-faced insulation? Does it matter? Is R-13 or R-19 sufficient? Your thoughts on more soffit vents? Any advice is appreciated.

 

[trythis]

Unfaced for attics.
Why don't you like blown cellulose (recycled newspaper)? It is loaded with borax and is mold proof, bug proof, wont burn, and doesn't itch if you have to move though it for electric installation. Blowing it is easier than rolling out specifically size rolls and you can make it as deep as you want.

If you are going to insulate any attic, go for R40 minimum.

 

[DzNuts]

Trythis, thanks for the idea. I am ready to insulate my finished ceiling but plan to use it as storage also and do not want to get fiberglass on everything I put up there. Nasty stuff! So I was thinking of putting batting side up to create a barrier (which I know isn't good for moisture). This may be just what I'm lookin for. Is cellulose safe to put against ic recessed lighting? How many inches is R30 and R40?

 

[padronanniversary]

so the blown stuff is easy to put down using the machine ? I'm curious, I was thinking about it. I did not realize it was not like fiberglass (i thought it was). hmm...options

 

[trythis]

You have to leave space around canned lights and such. Just make cardboard boxes the right size with taped on tops and remove the top when you are done blowing, leaving the box in place.

I think R30 is 9" deep, but that is in a packed space like a wall or between ceiling and floor. They label the bags at the store though.

The blowing machines are usually free to rent when you buy the insulation.

You still want a dust mask installing it.

 

[trbomax]

I believe r-41 is current code in mi for cielings. I have a combibation of ridged foam board (4") and 16 " of blown in. Works out to r-70 which I figured was the point of deminishing return.

 

[trythis]

Is there a code for garage ceilings? !

 

[Thirsty]

How can there be code for garage insulation? Most people don't insulate their garages at all.

 

[trbomax]

If its attached and heated it would be considered part of the house. I did not mean to infer that the code extended to all garages,its for homes,but a heated and a/c ed garage/shop should be built to the same or even higher code standards as a house,mine is.

 

[padronanniversary]

so do u have to leave space for canned lights if it is a IC rated light ?

 

[Thirsty]

If you are "occasionally" heating your garage with a space heater, R13 in the walls and R19 in the ceiling is plenty.
You want to use Kraft faced with the face on the inside.

 

[Jaguar Fan]

Here is something to consider. Let's say you put rolled bats between the ceiling joists of the finished ceiling.

In the winter, imagine standing in the garage with an infrared camera pointed at the ceiling. Here's what you would see. Wherever there is a ceiling joist, you would see a "stripe". That's because the wood of the joists is about R-3, in contrast to a high R factor for the insulated areas between the joists.

It would look like zebra stripes alternating warm, cold, warm, cold, etc.

If you use blown insulation covering the joists, the insulation will be more effective at helping you maintain a comfortable garage heat/cool wise.

 

[Dominico]

The reason I didn't like blown in insulation is due to previous experiences i.e moving or running new wires or replacing lights, however I will reconsider. Very good points to consider. I am still leaning towards the rolled but I will keep reading comments. Either way I got my main answer to my question. Thanks for all the advice!

 

[Steevo]

How can there be code for garage insulation? Most people don't insulate their garages at all.

I had this very discussion with a building inspector recently. He wanted to inspect the insulation and sheetrock in my detached garage/shop building, and I asked him why it needs inspection, since it isn't even required in the first place. He said I was right, and that they just liked to make sure that if any hazards were created by sloppy work, they want to point them out for the owners safety, but can't fail an inspection that isn't required.

 

[DzNuts]

You have to leave space around canned lights and such. Just make cardboard boxes the right size with taped on tops and remove the top when you are done blowing, leaving the box in place.

Putting cardboard around the cans just doesn't sound any safer than fiberglass covering them. Especially after they dry up after years of sitting next to the warm lights. I'd like to hear more comments on this.

 

[Steevo]

Putting cardboard around the cans just doesn't sound any safer than fiberglass covering them. Especially after they dry up after years of sitting next to the warm lights. I'd like to hear more comments on this.

I thought that was why there were "IC" or "Insulation Contact" can lights.
They can be buried under blown-in, and as long as you do not exceed the wattage rating, they are safe.

Like it says here: http://www.insulate.org/tech3.html

 

[DzNuts]

Talked with an electrician at work today. There is no problem with blowing insulation right over the cans. It is normal practice in new homes.

Where can a person find cellulose insulation? I poked around menards and didn't see anything besides fiberglass.

 

[trbomax]

Lowes and HD have it.About 1/2 the cost at HD.

 

[lewy]

Here is something to consider. Let's say you put rolled bats between the ceiling joists of the finished ceiling.

In the winter, imagine standing in the garage with an infrared camera pointed at the ceiling. Here's what you would see. Wherever there is a ceiling joist, you would see a "stripe". That's because the wood of the joists is about R-3, in contrast to a high R factor for the insulated areas between the joists.

It would look like zebra stripes alternating warm, cold, warm, cold, etc.

If you use blown insulation covering the joists, the insulation will be more effective at helping you maintain a comfortable garage heat/cool wise.

I agree with Jag fan - my choice would be some kind of spray foam. My mom is allergic to newspaper ink, so I can't use cellulose. Plus, the more I read about foam insulation, the better it seems. It would seem like a pain if you have to rewire or something though - I didn't think of that...

 

[Rosco]

Putting cardboard around the cans just doesn't sound any safer than fiberglass covering them. Especially after they dry up after years of sitting next to the warm lights. I'd like to hear more comments on this.

The cardboard is spaced at least 3 inches away from the fixture and open on top. I have these non-ic lights in my house. Although it appears safe, the insulating property is zero around the lights, and I have about 20 of them. I plan on replacing all of them with IC lights in the future.

 

[trythis]

I dont think the cardboard is going to spontaneously combust if you space them according to the lights requirements. IF you pushed the cardboard against the housing and over watted the fixture by a factor of 2 or 3, you might get them up to 451 degrees.

 

[LocoCoco]

Here is something to consider. Let's say you put rolled bats between the ceiling joists of the finished ceiling.

In the winter, imagine standing in the garage with an infrared camera pointed at the ceiling. Here's what you would see. Wherever there is a ceiling joist, you would see a "stripe". That's because the wood of the joists is about R-3, in contrast to a high R factor for the insulated areas between the joists.

It would look like zebra stripes alternating warm, cold, warm, cold, etc.

If you use blown insulation covering the joists, the insulation will be more effective at helping you maintain a comfortable garage heat/cool wise.

What my dad did for his garage ceiling (and I'm thinking of doing the same to mine) was put R-18 parallel between the joists (2"x6" trusses), then laid R-28 batts perpendicular across them. In his case, this is a vaulted ceiling in the loft so there's no room for storage anyway. In my garage, the trusses aren't vaulted and I'm liking the idea of attic storage space so I may not go this route.



LC.

 

[VHF]

Putting cardboard around the cans just doesn't sound any safer than fiberglass covering them. Especially after they dry up after years of sitting next to the warm lights. I'd like to hear more comments on this.

I too would worry about the combustibility of cardboard. I have heard of people building a "box" out of drywall around non-IC rated can lights. The drywall box would be sealed up airtight with expanding foam on the attic side and then the whole thing would be buried in the attic insulation. This technique was being used to build energy-efficent homes before IC-rated can lights were readily available.

Now, while the drywall itself is non-combustible, this method would probably result in the can light running at a higher temperature than the designers intended because the hot air wouldn't be convecting up and away into the attic.

Personally, an airtight IC-rated can with a nice cool florescent or LED bulb would be my first choice for a new installation! (Or use a CF in an exisiting can light to cut the heat production by 75%.)