Fiberglass Insulation Do's and Don'ts

[FEF]

All,

I'm in the process of adding on a 37x40 attached garage. I'm waiting on trussess, now. During this time of waiting (it's killing me), I'm thinking of how to insulate the walls and ceiling.

I think I can figure out how to insulate the walls, but insulating between the rafters (trusses-24"oc), has me scratching my head.

What's the best way to insulate my roof area? Is it as easy as buying fiberglass insulation that's inside plastic? It looks like I could just tack it up there, near the roof sheathing.

It can't be that easy.... I've got to be missing something.


Thanks in advance,

 

[REFLEXX]

here's what I did:

http://garagejunkies.net/showthread.php?t=916&page=3&pp=10

regular insulation R19 & R30, use a hammer tacker (a good heavy duty one). Long sleeves, goggles and a real mask. So far it's been the "most uncomfortable" part of my shop build. Hot sweaty, itchy, foggy.

But it goes quick, once you're down to a system. I didn't use the plastic covered stuff simply because I knew I'd be cutting many pieces to fit. Staple it just enough to stay in place before the walls/panels go up.

The "right" way is to staple the paper "tabs" to the inside of the studs, not in the face. So they don't interfere with the drywall or paneling. That's what I did, but in the end, I don't think it made a poop of difference.

Cutting insulation was a *****, then I figured out how. put a piece of plywood on the floor, then the insulation, then another piece of plywood (like 1ft x 3ft) as your straight edge. Step on it and cut with a sharp utility knife. Much easier with the insulation compressed.

enjoy!

 

[W-Cummins]

The "right" way is to staple the paper "tabs" to the inside of the studs, not in the face. So they don't interfere with the drywall or paneling. That's what I did, but in the end, I don't think it made a poop of difference.

Not if your using the facing for it's intended use as a vapor barrier you don't. It's made to overlap at the joist edges. If you don't want the vapor barrier then just use unfaced batts and the little wire/rods made to support it from the under side untill you put up the drywall. You will also want to have an air space between the sheeting and the insulation to allow air movement from the sofits to the ridge vent. If you don't you may have problems with moisture/rot on your roof sheeting

William...

 

[D-Cal]

I hammer stapled up the 6 mil vapour barrier to the trusses (allowing for overlap on the walls) in a row just wider than the length of one batt of insulation (I used Roxul - highly recommended). Then I took the step ladder (hint: next time, get a rolling scaffold with enough room for you and a stack of batts) and went along the row "inserting" the batts as I went. Staple the barrier up for the next row and repeat. The last row is a bit tricky, just fold the batt in half, insert and pull it into place from below, staple the barrier on to hold it up.

I couldn't just stick the batts between the trusses and have them stay there because I was remodelling an existing garage. The blind one-eyed crack ***** who built it in the first place (I've called him many bad names since we moved in 2 years ago) couldn't manage to line the trusses up 24" on center for me. Some were out by as much as an inch and a half, which of course messes up two rows.

 

[FEF]

Well..... Maybe I only thought I knew what to do.

I don't think I understand some of the written discriptions. I guess I need to post a few pics.

Walls:
The walls are up. Currently, I have stick frames with t-111 on the outside. There's no vapor barrior, yet. It's a very simple shell, so far.

- What now? I need to put insulation in before the inside ply (for the shear wall) goes on.

I thought the facing, the paper glued to the fiberglass, was the vapor barrior. Am I wrong?

Roof/Ceiling:
The shop has (will have) exposed trusses. Currenty, I have no plans to hang sheet-rock (22') up there.

I understand that there should be air space between the insulation and the wood sheathing. I just don't understand how I'll make that happen, if the facing is stappled to the bottom edge of the truss.

Plus... I don't have roof vents in the plans. I hadn't really given it much thought, as it's a rather large open area. I still have time to add them. Should I???

HUMmmmmmm.... Right when you think you've got it figured out.....


Thanks for the help.

 

[moefuzz]

This might be someting to consider....

One thing I did when I built a sound room in the basement was..


I used the extra cutoff pieces of drywall to line the walls (screwed to the plywood between the 2x4s) then I set my R30 insulation in, sealed with a vapour barrier, then drywalled the walls. I did the same on the roof.. I inserted cutoff peices of drywall in between the above (floor joists) 2x10s, then stuffed the joists with a vinyl backed industrial insulation and put up drywall for a finishing touch.

The room was very well insulated....

And When you walked into the sound room, There was a noticeable difference in background noise. It was kind of eery when entering as people are not used to being in a space with such a low background noise. ... I could make all the noise I wanted in there and nobody complained (about the drums, or the massive stereo system)

----------------------------

view 24 albums from the drop down menu at http://spaces.msn.com/moes-garage/

 

[W-Cummins]

FEF Well..... Maybe I only thought I knew what to do.

I don't think I understand some of the written discriptions. I guess I need to post a few pics.

That might help are you west of the mountans?

Walls:
The walls are up. Currently, I have stick frames with t-111 on the outside. There's no vapor barrior, yet. It's a very simple shell, so far.

sounds good t1-11 and studs 2X?

- What now? I need to put insulation in before the inside ply (for the shear wall) goes on.
I thought the facing, the paper glued to the fiberglass, was the vapor barrior. Am I wrong?

No that's correct the kraft paper has a "tar paper" type backing on it and is a vapor barrier. There is some debate about where in the wall the vapor barrier is suposed to go ( depending on the need to heat vs cool most of the year) As it is now your commited to having it on the inside That is probably the proper location for you anyway. So over lap and attach the facing to the edges of the studs so you have a vapor barrier in the walls.

Roof/Ceiling:
The shop has (will have) exposed trusses. Currenty, I have no plans to hang sheet-rock (22') up there.

Are these 2X4 trusses? Are they scissor trusses or do they have a bottom cord or
storage trusses??

If they are only 2x4 and you have to have the insulation attached to them up by the sheeting your not going to have enough space to have an air space above them

I understand that there should be air space between the insulation and the wood sheathing. I just don't understand how I'll make that happen, if the facing is stappled to the bottom edge of the truss.

You will not be able to. You might want to use some other type if insulation if you need to attach it there. If they are a truss with a bottom cord you could atach the insulation to it and then add a sheet rock ceiling.

Plus... I don't have roof vents in the plans. I hadn't really given it much thought, as it's a rather large open area. I still have time to add them. Should I???

I would want a ridge vent and sofit vents too if it was my place

William....

 

[Paradise Ridge]

I'll jump in here.

I priced out all the materials need for my 30x30 figuring R30 roof, R19 ceiling (2 story) and R19 in the walls. After figuring in staples, foam for wire runs, etc. I called the local insulation contractor and got a bid for the same thing.

The difference? $45.00.

They did the whole job in a day while I sat in my lawn chair and sipped cold, refreshing beverages.

It would probably cost $45.00 in gas to get materials and laundry soap to get the fiberglass out of my hair and cloths.

Call around and get estimates. I'd recommend it!

Scott

 

[FEF]

Well....

It would appear that my bigger issue is roof vents. I'll have to have a talk with my contractor.

BTW, they are scissor trusses. My understanding is that they are not designed to hold much, if any weight. If it's true, this is good and bad. I'll have room to tilt my truck cab, but not as much overhead storage space.

It would appear that the best way to insulate this type of root trussing is to hang sheetrock. If I do that, I'll pay someone to rough it in...

Here's an idea...
WHy not hang insulation on the lower portion of the trusses. If I recall correctly, hanging the insulation, with the edges overlapping the rafter, is an acceptable application, too. Sure, I'll loose storage area, but at that ceiling height I'll have PLENTY of vertical shellf space.

In my particular project, I suppose the main question is, how much weight can I hang from scissor trusses??? I have no idea. I'm hoping that it's at least about 250lbs, or I'll never be able to work up there.

Great discussion. I hope others can benifit as much as I am.

 

[randii]

Imagine meeting you here, Fred!

Are you trying to vent the attic above the insulated ceiling? Basically, keep just the work area climate controlled?

My shop lacks a ceiling and any sort of insulation... but then again, I'm in central California, so I can heat or cool reasonable well with a portable electric fan or propane radiant setup. I have soffit vents at the eves and gable vents on the ends, and it got pretty hot in the attic, until I added a ridge vent at the peak. Much better now... to the point where I am thinking about retrofitting a peak vent to my house, as well.

Randii

 

[FEF]

Randii -

Ok... To sum it up, It appears I'm not in as bad a shape as I thought.

I've believe these statements are true:

- The paper on the back of the insulation is the vapor barrier.
- You shouldn't install the insulation with the fiberglass touching the roof's wood sheathing.

This leaves my project in pretty good shape... mostly. I'll put the insulatoin in the walls, with the backing stappled to the 2x4 studs. Then, I'll put sheet-rock over that. I'm not in any hurry to put all the sheet-rock, though.

It's starting to become evident that I'm going to have a more residencial type ceiling in my garage. I can live with that, as it will be about 20' high at it's peak. White paint will make it very nice in there, with standard lighting. As the soffet vents are provided by the truss company, I have that covered. It looks like I'm missing, at the very least, gable vents. The ideal thing would be ridge vents, though.


That appears to be the plan, so far.

 

[z28toz06]

I hammer stapled up the 6 mil vapour barrier to the trusses (allowing for overlap on the walls) in a row just wider than the length of one batt of insulation (I used Roxul - highly recommended). Then I took the step ladder (hint: next time, get a rolling scaffold with enough room for you and a stack of batts) and went along the row "inserting" the batts as I went. Staple the barrier up for the next row and repeat. The last row is a bit tricky, just fold the batt in half, insert and pull it into place from below, staple the barrier on to hold it up.

I couldn't just stick the batts between the trusses and have them stay there because I was remodelling an existing garage. The blind one-eyed crack ***** who built it in the first place (I've called him many bad names since we moved in 2 years ago) couldn't manage to line the trusses up 24" on center for me. Some were out by as much as an inch and a half, which of course messes up two rows.

why did you hire a male crack *****? if he's blind it doesn't matter how many eyes he has, does it?

 

[danski0224]

All,

I'm in the process of adding on a 37x40 attached garage. I'm waiting on trussess, now. During this time of waiting (it's killing me), I'm thinking of how to insulate the walls and ceiling.

I think I can figure out how to insulate the walls, but insulating between the rafters (trusses-24"oc), has me scratching my head.

What's the best way to insulate my roof area? Is it as easy as buying fiberglass insulation that's inside plastic? It looks like I could just tack it up there, near the roof sheathing.

It can't be that easy.... I've got to be missing something.


Thanks in advance,

Don't do fiberglass.

Do blown in cellulose.

 

[Cboz44]

I second the blown in insulation idea, just had my garage done took about 20 minutes and cost less than what I could by the batting for.

 

[EvilEye]

Check my post under pole or stick buildings. I posted a picture of my garage under construction with sissor's trusses showing before the siding went on the end wall.
I was able to put standard r-30 between the trusses on the bottom chord. The builder put in ridge and eave vents. I had to buy the pink styrofoam pieces (that let the air move from the eave to the ridge) and place them the first 3 feet from the wall towards the ridge. these styrofoam pieces hold the fiberglas batts down from contacting the roof deck and let the air move from the eave to the ridge.

 

[Krodad]

Honestly, R-30 fiberglass is not going to give you R-30 when it all boils down to real-life conditions.
You will get higher performance BY FAR from installing blue or pink foam over the studs on the interior side, then use fiber reinforced gyp board (not paper faced drywall) directly over the foam. This will eliminate the studs from being a thermal bridge, and stop the ghosting of the drywall from moisture migration when you attach directly to the studs, with no thermal break. If you really want to do the belt and suspenders approach, you can have the cavity between the stud sprayed with urethane to make everything super tight, quiet, and without equal in performance.

Even 1" of R-5 styrofoam (NOT the white beadboard!!) will perform better than 6" of fiberglass. And styrofoam (EXTRUDED polystyrene) is a very effective vapor retarder in the described conditions. This plus the gyp board (dens-glass or similar) will eliminate moisture problems as well.