insulating garage attic

[picksbigwagon]

We built a new house this fall, the garage had 2x6 bottom trusses put in so I could insulate and use for storage at a later time. I haven't cut the hole to put in the access yet, but does should there be a vapor barrier between the drywall (already installed) and the insulation? What about when I put sheets of plywood for flooring in the attic, should there be a vapor barrier since it will be a "cold" storage?

There is a lot of room up for "stuff" that I want to get access too......

thanks in advance

Oh yeah, do you think I would need to pull a permit to do this work?

[LightningBG]

Oh yeah, do you think I would need to pull a permit to do this work?

I don't know about the vapor stuff, but there is not a chance in he%% I would pull a permit for that.

If there is or isnt a vapor barrier under the sheetrock, there isn't much that you can do about it now (besides pull down the rock, which i wouldn't do.

Might as well cut the hole, install your door/ladder and start rolling out the insulation. Then you can figure out if you need a vapor barrier on top, then plywood.

[CAMAN]

Vapor barrier between the drywall and trusses, YES. Between the insulation and attic, NO.

[picksbigwagon]

So there should be a vapor barrier there already then Caman?

[CAMAN]

Unsure if new homebuilders would put it into an uninsulated garage, they would if you asked, but don't know if it's standard procedure. Is the drywall taped and mudded? Wouldn't be too difficult with a couple buddies to remove if its not and only screwed, not nailed.

One way to remember where the vapor barrier is to be placed is it always goes on the warm side of the insulation, you're gauranteed mold if it's placed on the cold side.

[quijibo]

If they skipped the vapor barrier step, you could use a vapor barrier paint on the drywall. I believe that one or two of the formulations of BIN and Killz primers qualify.

I would probably call in about a permit, it shouldn't affect your tax valuation and the inspectors can usually offer some great tips. They have seen the best and worst ideas out there. As a Carpenter, I won't even consider buying a house that has had uninspected work.

Adam

[Surface Tension]

It would have been a lot easier to insulate before the drywall was up. If the VB isn't there its too late to add it now. Use unfaced bats when you insulate.

Hopefully you have an energy truss so getting enough insulation over the top plate and allowing airflow won't be so tough.

Pick up a ladder-in-an -attic then cut out your opening and frame it.

You'll lay the 6" bats in between the cords. . Your call there if you want to boost the R value with 6" bats across the cords.

To get more height for the additional insulation under your plywood storage use 2x6 across the cords.

[LightningBG]

It would have been a lot easier to insulate before the drywall was up.

How the heck you you insulate before the drywall was up? Staple the facing paper up there? I thought all ceiling insulation was done after the rock was up...?

[MNice]

In my opinion, a garage is not tight enough to warrant a vapor barrier. Just think of the overhead doors, they are about as weather tight as a corn crib. A good few coats af paint will do what you need, especially if you are not heating 100% of the time. To reinforce my opinion, the energy code completely exempts garages...

Exceptions:

l. Portions of the building that do not

enclose conditioned space, including

garages.

google MN 1322 for the residential energy code, its all there.

[upnorthvoice]

This is my 2 cents worth and how I interpret the code. The garage is an exception to the energy code until it is an enclosed conditioned space. When the garage is insulated, finished with drywall and a heat source is used ,it is now a enclosed conditioned space and needs to be protected from mold growth with a vapor barrier.

The builder may have installed drywall on the garage ceiling as the fire stop instead of installing drywall at the house to garage wall up to the roof deck.

There may be a vapor barrier and the home owner will determine that when he cuts a access to the attic area.

If there isn't a vapor barrier the least you should do is a good coat of "vapor barrier primer" to the ceiling drywall before painting. The home owner should consider installing a bath fan in the garage to control humidity.

[CAMAN]

I agree with upnorth, the garage is now enclosed and conditioned once you add a heater. When you drive a snow covered vehicle into a heated garage that creates a ton of humidity and will very easily create mold growth. I would do whatever I can to get some sort of moisture barrier in there if there isn't one. Best to check so you can decide what action to take.

[cavalierowner]

picksbigwagon, have you actually checked to see if there is a vapor retarder? I ask because builders and inspectors are so accustomed these days to installing them that I would almost be surprised if there wasn't. Because it's an attic space, by code there has to be access; you could very easily check. Or just cut a small hole in the ceiling that is easily patched.

If you decide to heat the garage, you will need a permit to install the heater. If the inspector looking at the heater installation has anything on the ball at all, he will require the entire garage conform to code. At that point you will need to make the garage conform to the energy code if it is designed to be warmed above 50 degrees; that's the definition of a conditioned space, heated garages are not excepted. At that point you REALLY need to get a vapor retarder installed. As stated, you are likely to very quickly get condensation and mold and then you really have a problem.

Sorry to sound like such a wet blanket, but it's much easier and cheaper to resolve issues in the beginning than after the fact. I would suggest you contact the local inspector and see what they say. You would be surprised at how helpful they are when you contact them ahead of time. They don't have much of a sense of humor when you do something that doesn't meet code or that was done without a permit.

[11-87]

Ok,

Did you build the house?? or a contractor?

If you have actual attic storage trusses, why not run proper vents all the way up each rafter to the peak, and then insulate the storage above? you could insulate, and then poly the attic room.

If your not sure about what you have, why not call your contractor who built it..

[picksbigwagon]

Okay, the trusses are attic trusses, there is no access to the space yet, I won't call it an attic until I cut an access and install pull down stairs. What I have gathered so far is:if there is a vapor barrier that is a good thing, if there isn't, that is a bad thing. I could put some water proofing paint (generalizing here!) on the ceiiing which could help. No plastic=unfaced insulation, plastic=faced insulation.............

No plastic, no garage heater

[Surface Tension]

Are the walls sheetrocked? If not then where the wall meets the ceiling you'll see the poly hanging down if they used a VB.

I wouldn't get all worked up till you find or don't find a VB in place.

Another question is at what temp will you be heating the garage at.

The VB primers are effective . Here is some documentation on the subject.

[LightningBG]

I'd go with the paint if there isn't any plastic. And I'd skip the permit. What heater? Just have someone qualified hook it up.

Installing Vapor Diffusion Retarders in Existing Homes

Except for extensive remodeling projects, it's difficult to add materials like sheet plastic as a vapor diffusion retarder to an existing home. However, many existing homes don't really need a more effective vapor diffusion retarder than the numerous layers of paint usually on their walls and ceilings. These multiple layers are quite effective as a vapor diffusion retarder in all but the most extreme northern climates.

"Vapor barrier" paints are also an effective option for colder climates. If the perm rating of the paint is not indicated on the label, find the paint formula. The paint formula usually indicates the percent of pigment. To be a good vapor diffusion retarder, it should consist of a relatively high percent of solids and thickness in application. Glossy paints are generally more effective vapor diffusion retarders than flat paints, and acrylic paints are generally better than latex paints. When in doubt, apply more coats of paint. It's best to use paint labeled as a vapor diffusion retarder and follow the directions for applying it.

[picksbigwagon]

walls in the garage are insulated and sheet rocked. I won't know about the rest till I crack the ceiling....

[Rooster7]

walls in the garage are insulated and sheet rocked. I won't know about the rest till I crack the ceiling....

I would just call whomever installed the rock and ask them.

[picksbigwagon]

I was just looking at photo's of the build and there is a picture of my son standing in the "pink" garage with a very cloudy looking ceiling....so I have photographic evidence that their is a vapor barrier........so faced or unfaced insulation? before I add plywood of the top of it

[cavalierowner]

Glad to hear you have the vapor retarder. Definately use unfaced insulation.

[Tom7227]

If you're thinking about storing stuff up above you should do some research on how much weight you can add without causing problems. Some of those trusses are built on the light side and can't take a whole lot of downward stress. If you break any you're going to really regret it.

[cavalierowner]

Tom7227 has a very good point. I know you said in your first post that you had the trusses designed for storage, but did the contractor tell you how much? He should be able to tell you, in pounds per square foot, what the bottom chord (the botton 2x6 you said you have)will carry. From there I could at least give you a feel of how much could be stored.

[LightningBG]

Another thing you might want to consider is "how" you are going to get the plywood up there.

Step 1, cut the hole, OK

Step 2, install stairs/ladder. Ok, but will a full sheet (4x8) make it through the hole with the stairs already installed?

Might have to heave the sheets up there before you install the stairs/ladder.

Just something to consider so you dont get them installed and then have to pull them out to get some more space.

[PurpleFloyd]

I did it in our garage a year ago. You just rip the plywood in half so you are using 2x8 instead of 4x8 sheets.

[Surface Tension]

Picks, the VB is good news.

Use unfaced for sure.

Attic truss could mean a few things.

Just curious. What are the dimensions of your garage and what is the pitch?

Depending on what you have(room in attic truss) you might consider a stair way against the back wall instead of the ladder.

That would mean framing in a stair well and adding a door.

I thinking Man Cave up there.

You'd insulate it differently also.