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DangerMouse 07-26-2008 12:45 PM

ceiling help please?
hi everyone! i have a new addition and need to put in the ceiling. what exactly is the most common way to install new ceilings? from the bottom up, i imagined drywall, then batt insulate between 2 ft. ceiling truss areas, then blown insulation above that to finish. any easier way i can eliminate the batt? plastic stapled above the drywall to hold the blown insulate in case of ceiling drywall repairs down the line? ( so it won't fall out) as many different suggestions how i can finish this project as possible is greatly appreciated! maybe brown 1/8" hardboard above the drywall? hmmmmm...


AtlanticWBConst. 07-26-2008 05:23 PM

6 mil+ Poly (plastic) stapled to the strapping, or the truss-chord bottoms should do it.

bjbatlanta 07-29-2008 03:00 PM

If you decide to go with the plastic, make sure to get it tight to the joists and use enough staples to make sure the weight of the insulation doesn't pull it loose. If the blown insulation gets between the joist and the drywall, it will cause nail (screw) pops. I always glue and nail/screw drywall to help eliminate "pops", so I would not recommend the use of plastic. That said, in your area the use of adhesive may not be the norm.

DangerMouse 07-29-2008 06:13 PM

still confused here.... let's try for a cross section of the new ceiling... starting with the bottom... drywall...mounts to furring strips..... then.....what above that?....

quoting-a-job-need-help 07-30-2008 10:56 AM

i say just use old bats insulation and lay down the poly plastic to protect from mold then spray itit will give the best seel and u wont have to worry about nail pops

DangerMouse 07-30-2008 11:33 AM

paper side up or down?

quoting-a-job-need-help 07-30-2008 11:34 AM

paper side down

RippySkippy 07-30-2008 01:38 PM

Outta curiosity, why mess with the bats at all. Is there a reason you can't use all cellulose? I don't much care for FG and will not use it if at all possible. You'll have to get the blower anyway, why not blow it all at one time?

bjbatlanta 07-30-2008 02:07 PM

I think the idea of using the batt insulation is because the blown stuff "settles" after a while. At least with the batts underneath, you're guaranteed a certain amount of R value. In this area, it's pretty much just blown in accessible spaces (batts where it can't be blown later). Our winters aren't that severe though.

DangerMouse 07-30-2008 04:22 PM

the batt or hardboard is for holding the blown insulation in place if (God forbid) the ceiling drywall ever needs repair. (so it does not fall on you) but as i see it now, you guys suggest, from the bottom up... drywall, furring strips, batt in rafter openings, plastic sheet stapled on top of the rafter bottoms, then blown on top of it all? SOUNDS warm enough! =o)


quoting-a-job-need-help 07-30-2008 09:22 PM

and the blow stuff can get inbetween the drywall and cause screw pops

Maintenance 6 07-31-2008 06:51 AM

If it were mine, I would install baffles to the underside of the roof sheathing at the eaves. Durovent or something similar. Then staple 6 mil poly to the underside of the lower chord of the trusses. Install the drywall. Finally, blow in the cellulose. Properly installed it won't settle very much. I wouldn't even mess with the fiberglass. I've never seen drywall screw pops because of cellulose unless the drywall wasn't fastened well enough to support the weight. But maybe, I've never been in the right place. Anyhow, the drywall installed first will prevent any cellulose from getting between it and the trusses.

RippySkippy 07-31-2008 08:08 AM


Originally Posted by MdangermouseM (Post 144421)
...from the bottom up... drywall, furring strips, batt in rafter openings, plastic sheet stapled on top of the rafter bottoms, then blown on top

This doesn't sound right unless I'm not understanding it right.

If you have the plastic stapled to the bottom of the rafter/truss and put a furring strip blow that, you'll be creating a small cavity where there will only be air and not insulation. Unless your ceiling is way out of plane, I would skip the furring strips all together, staple the plastic to the bottom chord of the truss, hang the drywall, then blow in cellulose. There's NO way you can blow insulation between the bottom chord and drywall to pop way. If you blow in cellulose before the drywall, you can get it between the plastic and bottom chord.

If the drywall needs repaired in the future, with cellulose you just take a snow shovel and move it aside, make the repair and fluff it back into place....not a big deal one way or the other. If the repair is from water damage, with either product, it will need to be removed.

If the ceiling drywall is fastened properly, it will support the weight of blown in cellulose. If you figure an R60 you will only have about 2.3 pounds per square foot, that's roughly 16" once settled. The instructions indicate how much it will settle and the depth you should have when it's blown in. If you plan accordingly, you won't be disappointed.

dhag 07-31-2008 08:39 AM

I would install furr strips to joists, install poly vapor barrierthen rock, then blow. Of course this is a lot easier if you have access to the attic/ceiling space. Otherwise you have to cut open ceiling to blow insulation in. But you can't blow before rock and expect poly to hold it. Some codes may allow a netting or home wrap material which will hold insulation until you rock. We do this in minnesota for tuck under garage lids. Make sure you use 5/8" rock and long enough screws to get through the furr strip to the joists.

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