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blown in or roll advice


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09-17-12, 08:35 PM   #1  
blown in or roll advice

Hello. I'm finishing an area above a attached type garage, that is 1590 sq'. It is unheated, and trying to keep it warmer in the winter below, as it is a aircraft hangar. One wall is fireboard and insulated to the house. 2 walls are already batt insulated. The front end is a giant bifold door which I intend to glue Styrofoam r10 sheets to. Ok, for the ceiling. It will never be nothing more than a vacant, non storage type area. The engineered trusses are 24" on center and are of 2x4 material. My intention, is to lay 24" wide R-13 between joist's, then go back over the other way with r-21 for a total of around 10" of batt. My other option is to blow a bunch of cellulose in there. I have read a bunch, and feel I will not get the best of coverage, and will cost me more money. I am looking at right at $900 total for all batt insulation...at this time. Get me on the straight and narrow here, before I pull the money cannon trigger. I really don't want to deal with the blown in stuff...as I've dealt with it before. Thx, DM

 
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09-18-12, 02:29 AM   #2  
I think your method using the roll insulation will work just fine. Blown in stuff gets everywhere, and although it may be an industry standard, seems a little messy for the DIY. Make sure you don't lay in insulation that blocks any soffit vents or outside air entrance as you will need it to keep the air moving in the attic. Do you have ridge vents? I worked at the airlines for a number of years, and my vision of a hanger may be a lot different than what you have. The ones I am used to seeing you can pull in 3 L10-11 Tristars, and back in 2 727's between them.

 
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09-18-12, 05:13 AM   #3  
LOL, Larry, that sounds like a blimp hanger.

CM, I assume drywall on the ceiling. If 1/2" or less, then you may need to be careful about the load capacity. I don't have a number at hand and the amount you are talking sounds like it won't be too much, but check if you go cellulose.

Fiberglass batts are light, but details count, so if this is the path, be neat. If you have soffit venting, install baffles that prevent wind washing of the ends of the batts.

I didn't hear vapor barrier, but especially a garage where snow melt or rain will have to go somewhere, you don't want it reaching a cold surface. Since this is going to be unheated, I would still be worried about moisture. You may end up leaving a window open after you get it sealed up.

As an example, think about the mold problems a bathroom can have and that exhaust fan that has to be run to dry things out. That garage is going to be a lot colder, thus can tolerate much less moisture.

Also, check into mineral wool batts. They are much denser and may be an option. More expensive so maybe not.

Bud

 
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09-18-12, 12:49 PM   #4  
When I looked at blown-in insulation a few years ago, I was tallying up the material, its transportation, the blower and it rental, transportation, and so forth.
Someone suggested that I find out what a contractor would charge for a turnkey job. I was doubtful, but called anyway.

It turned out that I could have a contractor do the work for less than the cost I would have had to pay for just the materials, not to mention transportation; rental of blower and so on.

Having said that, I would suggest getting some quotes to see how it stacks up.


Chris

 
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09-19-12, 11:15 PM   #5  
paper side down

Hello and got the last posters advise. I may get a price for blowing in over the already purchased r-13. Ok, so since it's a paper back product, should I staple this up to the ceiling now, prior to drywalling, or "lay" it down between the joists after the fact? Unsure if there is an advantage, other that the ease of installing it prior to drywalling the ceiling. Thx for the advice. Great place here!

 
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09-20-12, 03:05 AM   #6  
I think it will depend on your time frame between insulating and drywalling. You don't want the insulation to sag out, although stapling would be an option. Most of the time the drywall is installed and the insulation laid in the bays.

 
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09-21-12, 08:31 AM   #7  
should I staple this up to the ceiling now, prior to drywalling, or "lay" it down between the joists after the fact?
This is about the ceiling of the room above the garage, right? If so, what kind of access will you have to the space after the drywall goes up?

 
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09-21-12, 11:12 AM   #8  
I intend to frame out one entry point for access, about 3' in length. (between as set of joists) I was going to put some storage up above, then changed my mind. This span was not designed for any type of storage or regular foor wear.

 
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09-21-12, 12:29 PM   #9  
I intend to frame out one entry point for access, about 3' in length (between a set of joists).
OK, then you will have access to do whatever you need to do.

What is the intended purpose of the room below? Bedroom, den or other living space? Or storage?

One quick comment on blown-in insulation: It performs great and yields a high return on investment so long as it stays exactly where you need it - and it can be a PITA to keep in place and out of soffit vents and other air flow spaces.

 
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09-26-12, 08:23 PM   #10  
Hello again. I've been giving it some thought and I "may" blow in over the batt R-13, simply due to the fact it'll be a huge PITA to roll out the other insulation, at the end. Anyway, do I need to install rafter vents, to prevent the insulation from spilling out onto the soffits? Keep in mind, this is a unheated attic type space. I'm more or less trying to keep the cold out. I will already have 4" X 24" batts, paper faced, laying paper side down, meeting the drywall. (ceiling)
I wanted this batt in first (my pref). The cost of the bags will be cheaper than rolls of R19 rolls. DM

 
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09-27-12, 08:53 AM   #11  
do I need to install rafter vents, to prevent the insulation from spilling out onto the soffits?
If you have soffit vents, you need to install baffles or a mesh barrier or some means to prevent their being blocked. If you don't have soffit intake vents, you need to install and protect them.

Keep in mind, this is a unheated attic type space. I'm more or less trying to keep the cold out. I will already have 4" X 24" batts, paper faced, laying paper side down, meeting the drywall.
The only effective air-cavity insulation is dry insulation. If the paper on the face of the batts is backed with tar, then you have already made one important step toward that goal.

Controlling the heat in your attic is not a goal of either insulating or venting it. In fact, the primary function of attic ventilation is to remove water vapor and keep the insulation as dry as possible. It will also reduce the chances for icing and make that space less supportive of mold and mildew. As a final benefit, an effective soffit-to-ridge ventilation system is probably the best method of preventing ice dams from forming on the eaves.

 
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09-27-12, 11:01 AM   #12  
it has tar on paper. i was thinking of running a roll of r-30 around the rafter edge to soffit area. this would perform insulating as well as making a dam from the celulosefrom getting on soffit.

 
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09-28-12, 08:16 AM   #13  
i was thinking of running a roll of r-30 around the rafter edge to soffit area. this would perform insulating as well as making a dam from the celulose from getting on soffit.
Rolling out and placing that batt of R-30 all the way around the perimeter seems like a lot of work, and sounds like a less-effective solution for two reasons. First, the shape of the batt will create a stair-step beyond its outer edge, above the part of the ceiling closest to the wall, where the R-30 isn't present unless it is notched to fit into every rafter bay. Notching it would be a real PITA and reduce the ventilation airway. Second, and more importantly, laying that batt in before blowing in cellulose is unlikely to prevent the cellulose from getting over into the soffits, IMX. That stuff goes everywhere. It can also migrate after the dust has settled. The batt would lessen the chance that it would get over into the soffits but not prevent that.

My favorite method for containing the insulation and protecting the venting is to staple 1/4" hardware cloth to the bottom of the rafters, from the top up to the point where it is 6", vertically, above the top of the cellulose fill. The fiberglass baffles are more certain to prevent the blown-in material from getting into the soffits, but they also constrict the channel a bit and reduce the effective wicking of the insulation.

Just my 2 cents worth.

 
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09-28-12, 08:48 AM   #14  
damn, that's alot of stapling...no? 1/4" cloth? I really do not understand what this is. I think you're creating a fabric damn the entire perimeter, correct? where do i find this stuff and how much is it? I also assume that each rafter bay would breath, instead of every other one, that I planned on doing with the styrofoam baffles.

 
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09-28-12, 11:48 AM   #15  
1/2" hardware cloth is actually metal fencing in 1/2" squares. You can find it in hardware stores or in box stores back where the fence stuff is. They call it hardware "cloth"....don't ask why. Personally I like the baffles, mainly due to my size and I don't fit in certain spaces, especially those pointy ones where roofs and joists meet. But, it is a good idea, so don't discount it yet.

 
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09-28-12, 12:39 PM   #16  
I really do not understand what this is.
Sorry 'bout that. 48"x50'1/4" Hardware Cloth.
damn, that's alot of stapling...no?
No, not really. Hardware cloth is really stiff, and tends to stay where you place it. As Larry implied, the tough part may be getting in position to place and staple it. But a couple of staples along the top plate or block and a couple up each rafter should be plenty.

I prefer the 1/4" mesh because it will contain pieces 1/4 the size that the 1/2" mesh will and it's still open enough to staple easily. The Styrofoam baffles will work too - I just prefer to allow all of the insulation to wick easily and directly.

 
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09-28-12, 01:43 PM   #17  
i see the pic and this would allow insullation to flow through into the soffits, as i see it. i already got the foam baffles today. thx folks

 
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09-28-12, 02:01 PM   #18  
i see the pic and this would allow insullation to flow through into the soffits, as i see it. i already got the foam baffles today.
It hasn't yet, in my experience. But, whatever method you choose, your attic and your house will be in a lot better shape because you did this. Not to mention your heating bills!

 
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09-28-12, 02:27 PM   #19  
Hi. Keep in mind, this 1600' area is unheated or cooled. One section of wall is attached to the house, which is already insullated with bats and 5/8" drywalled. I can only seeing it helping my house, a minor bit. I just wanted to keep the cold out, and if I were to pump electic heat (space heaters) into it, that it would containt it better. One of my walls is a 10' X 40' bifold door, which is basically now only plywood. I will attach styrofoam sheeting to this R-10 value.


Last edited by Nashkat1; 09-28-12 at 03:08 PM.
 
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09-28-12, 03:00 PM   #20  
That's right, it might not help your house all that much. OTOH, a really cold attached garage can become a heat sink - depends on how well separated it is, thermally.

I somehow got it in my head that you were insulating around a room above the garage, not insulating the garage itself. That can happen sometimes when you look at 20 or 30 threads in an hour.

I hope you enjoy your unusually well-insulated garage!

 
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10-01-12, 03:31 AM   #21  
paper or sticky mesh joint tape

Hello. Since I will not be mudding the ceiling this year, I still have to contain the cellulose for leaking (dust) from the joints. Will the sticky stuff that don't require the 1st layer of mud, do this job for me? I imagine it's more expensive, but I won't have enough time this year (natural curing temps) to put down any mud.
Please advise and thank you. DM

 
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10-01-12, 03:50 AM   #22  
I would seriously go ahead and tape the joints with paper tape and apply a setting compound. You can buy it dry and mix it up yourself. It comes in 5 minute (don't use it) up to 45 minute setting time. Not sure why you couldn't use that. Also I'm not sure what a "natural curing time" is, but 45 minutes is a blink of an eye. Just don't mix up more than you can apply in 15 or 20 minutes.

 
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10-01-12, 05:17 AM   #23  
no heating and air. outside "natural" temps starting to become fall like. I'm nexperienced enough to attempt a mudd job once, then realize it may fail due to the temps and then have to do it again....
hehehe, not me! DM

 
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10-01-12, 05:47 AM   #24  
Mesh tape will fall off in time if it is not embedded with mud, so that's out. If you don't want to do the mudding, then you may be able to use something like Blue tape of Frog tape on the joints that will last until next spring. Not sure.

 
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10-01-12, 05:57 AM   #25  
Better yet, getting a quote to hang/mud/tape ceiling and possibly turn key with paint. I don't think I'll beat the weather and looking to not stress out over it.

 
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10-01-12, 07:43 PM   #26  
You could caulk all of the joints, the way it's done in air-tight construction. just wipe them smooth so you wont have to much unevenness to tape over later.


Last edited by Nashkat1; 10-02-12 at 12:20 PM.
 
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10-01-12, 08:35 PM   #27  
That's a good idea. What type? I'm wondering if caulk, or by not mudding and painting will throw a curve to any fire code (protection) I recon I should get hold of my inspector to ask. Any thoughts?

 
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10-02-12, 12:19 PM   #28  
The author of an article I just read on this used expanding foam for gaps larger than 1/4" and flexible caulk for the smaller gaps. That article is How to Hang Airtight Drywall, by Myron R. Ferguson, in the September, 2012 issue of FineHomebuilding. Ferguson also has a couple of how-to videos for this, one for ceilings and one for exterior walls.

I'm wondering if caulk, or by not mudding and painting will throw a curve to any fire code (protection) I recon I should get hold of my inspector to ask.
It never hurts to ask, but it shouldn't affect any ratings, since you mud and tape over the foam and caulk. From the article:
Posted By: Myron R. Ferguson, in FHB No.229 Big globs of caulk will make the taping job a nightmare, so smooth the bead with your finger before it sets up. Likewise, cut off foam after it cures. To complete the air seal, tape the seams and the inside corners as you would for any other drywall job.

 
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10-02-12, 12:37 PM   #29  
Gotcha. Thank you for the help.

 
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