Blown in cellulose wall insulation - pole barn ?

[aribert]

I am in the process of building a pole barn as a hobby fab/machine/car shop. Pole barn is 34 x 58, front half is truss roof w/ 12.5 ft ceilings, back half is a stick built roof and a mezzanine (ceiling height is 8.5 ft). Ceiling will be perforated metal with cellulose insulation. I need to decide on wall insulation (which drives the build sequence). The exterior was house wrapped prior to putting up the metal. Heat source will be forced air, I will be able to heat one half of the pole barn only depending on the project at hand. Location is in Metro Detroit area.

Foam insulation (R14, professionally installed) is quoted at $6K. Fiberglass batts, R19, 8 ft wide, to fit between the posts will run me about $1.8K plus my labor. I have installed batts in wall cavities in houses but have never handled anything wider than 24 inches. If I install the 8 ft wide batts, I would be installing the interior girts in each section to secure the insulation prior to the wall covering (drywall). Last night I started looking in to a what if scenario - namely finishing the wall covering and then blowing in cellulose. Because the posts are 5.5 inch square (3 laminated 2x6s) with 2x girts on the outside to support the metal and there will be 2x4 girts on the inside to support the drywall, the wall cavity is 8.5 in except at the girts. I would expect to get somewhere near an R25 with the cellulose at a cost of about $1K plus my labor. I understand the cellulose will settle and I will need to comeback in a couple of years and top off the wall insulation. I am thinking the (physical) labor to blow in cellulose will be easier than hoisting the 8 ft wide fiberglass batts. I have limited experience with filling wall cavities with cellulose - one small house that had no wall insulation. I drilled holes at the top of each stud cavity and also at about 32 inches up from the floor - filling the lower hole first then the upper hole in each cavity. For that house I installed wainscoting to cover the lower holes and crown molding to cover the upper holes. For the pole barn I am considering a 1x4 on top of the drywall as a rub strip to hide holes at say 3.5 ft up and another 1x4 at the wall/ceiling interface to hide the upper holes. In a few years I would pull off the upper 1x4 and add more insulation.

What am I forgetting? Talk me out of doing cellulose (cellulose is starting to look very appealing).

 

[pcmeiners]

Fan of cellulose. When you blow in cellulose, you pack until the machine blower bogs down so there is little settling. Properly packed cellulose will settle approximately 3-6 inches in a 8 foot stud height over a decade. You could also hire a company to spray wet cellulose, but would take time to dry.
Cellulose's insulation value is far superior to fiberglass especially at lower temperatures and properly installed it inhibits air flow through it and around it unlike fiberglass. The main disadvantages is water leaks and cellulose do not mix and running electric or piping after it is installed is a problem.

 

[billconner]

I'm a fan of cellulose and dense packed cellulose in walls but have been told by masters that dense packing cavities larger than 12" deep and wider than 16 to 24" - basic stick framing - is hard or not possible. Planning on filling a large - 8' wide - wall cavity and planning on topping off later could work. I don't know if the drywall where it's settled will be cold and result in condensation or not. Clear sign to top off though.

I've used hole saw in drywall and then re-inserted the hole with tape and mud. Intrigued by idea of some "trim" covering holes but also worried about holes in vapor barrier.

Bookshelf girts would solve several of these issues.

I will be following.

 

[theoldwizard1]

Fan of cellulose.

Ditto !

The main disadvantages is water leaks and cellulose do not mix and running electric or piping after it is installed is a problem.

I know you said it has house wrap, but I would still get a quote on spray foam around all joints as insurance. Can anyone recommend DIY spray foam ?

You don't need to put up the "finish" wall first. You can use "skrim" stapled to the wood to hold the cellulose and install the finished wall later. Blowing is a 2 or 3 man job.

 

[aribert]

Thank you all for your responses.

Although I filled the wall cavities in an older house, that I was turning into a rental, by my self; I usually get my wife to load the machine while I am manning the hose while insulating an attic. I have a short extension cord with an electrical box with a switch in the middle of the short extension cord and I run the power to the machine thru the switched cord (where I am spraying the cellulose) then on to the machine. This way I can control the flow by turning the machine off when needed.

Normally in a residence one hangs drywall (on walls) top to bottom in part to support the ceiling drywall edges and so the uncontrolled gap is at the bottom covered by a baseboard. In discussing using cellulose in the wall cavities with my wife over breakfast this morning, she asked if I could drywall from bottom to top - install the first row of drywall on the walls and then fill the cavity, next row of drywall and fill, etc. Several of you mentioned (dense) packing the cellulose - I was not aware of doing so. I am thinking I may run the first row of drywall starting at the bottom and manually compressing the cellulose fill a bit before adding the next row of drywall. This might reduce the settling a bit.

Around here both Home Depot and Lowes have a minimum purchase of 20 bundles of cellulose for a free 24hr machine rental. Between my P/U and utility trailer, I can easily carry 20+ bundles and the machine. I would just break the insulation job into multiple 20+ bundle events.

Follow up question - wall vapor barrier. My reading so far seems to imply 6mil poly as a vapor barrier under the drywall (inside of the wall cavity). Your thoughts? This is a shop, not a residence. Less water vapor since no cooking or bathing.

 

[billconner]

I usually start drywall at top of wall but you could start at bottom and blow and then second row and blow. Not a bad idea except free loaner time constraints. You could look at netting - Google dense pack cellulose netting - which holds cellulose and allows you to blow through a slit in it. Have only seen pictures of that.

I have not looked for a while but the free loaners did not used to be very good at dense packing. You need an airlock machine to go that well. And yes, I would definitely put up a vapor barrier.