New Garage Insulation - Shredded Extruded Poly?

[The Fallis]

So I just recently bought a home. Which means a new garage (to me) aka project time to get it up to par. its come a long way from the shape it was in but there is a lot to do still. Currently trying to insulate for the winter on the cheap as other projects have all the budget currently...

Dimensions are 31'-5" Wide and 23'-5" Deep.
Lower (two side car spaces) are 8'-3" tall and center space is 12'-3" to bottom of joists.

So I am looking at using shredded extruded polystyrene as a near by company gives it away for free... Now I know the R value will be much lower than the board version of the same material. But will it be worth using at all if it is filling a stud cavity(3.5" thick)???

Also for installation sake - See photos of new garage.

Walls - Horizontal studs may make this slightly challenging. Thinking of laying (stapling) a vapor barrier of clear plastic sheet down on the studs and blowing in so I can see cavity fill prior to drywall/ply.

Ceiling - Same concept. "Cold Roof" style so clear plastic vapor barrier stapled to joists. 4 soffits per side to let the air flow through.

Would love opinions and input as this is not my area of expertise.... Concerned with Mold, electrical mixed with loose foam, wasting my time due to R-Value, fire hazards, etc.





Thanks Guys!!!!
Rob

 

[walrus]

Location would be helpful. Whether it works or not depends on how tight you can it to pack in. Fire would be an issue but cover it with sheet rock and that would be mitigated

 

[DC73]

So I am looking at using shredded extruded polystyrene as a near by company gives it away for free... Now I know the R value will be much lower than the board version of the same material. But will it be worth using at all if it is filling a stud cavity(3.5" thick)???

Interesting question. Minimizing air gaps might be difficult but then again it could work very well. This is one that might require the thoughts of some experts. Recommend you go to GreenBuildingAdvisor.com and visit their Q&A forum. They have some building science gurus that hang out there and they should be able to give you some good advice. They'll need to know your location as vapor barriers and other insulation details can be very climate specific.

I'd be interested to hear what they have to say about this

Good luck,

DC

 

[Highbeam]

Finer the shred the better. Air sealing to be done by the plastic so you're simply looking for R-value.

 

[rburke65]

Uniform shreds? Any close ups ofthe insulation?

 

[The Fallis]

Location is just north of Detroit, MI. So we have some nice cold winters ahead. As stated I'm purely looking for R Value. Looks as if they laid the framework and then a thick black plastic liner from top to bottom for the sides. Screwed the exterior siding (1/2" ply with design on outside) over that as an exterior barrier.

Eventually there will be a wood burning stove in one corner for heating so I have to try and seal up to make it worth while.

I haven't checked out the shred in person so I cannot confirm the size. The game plan was to blow as much as possible and slightly over fill so board some what compresses the gaps.

Regarding fire since that was mentioned. Was planning on 1/2" Sheetrock since I can get it for roughly $6 4x8. Figured that was the best route if I am going to put the time into it anyways...

 

[Firebrick43]

Blowing into solid or non vented cavity doesn't work well. It will try to come back up and out. There is a netting used with dense pack cellulose. It is stapled and glued up to the framing. The idea is that you can blow it in,see it, even touch/compress it. The air instead of trying to escape back out the entrance hole immediately exits though the mesh.

It's probably not available at your local lumber store but was available to me here in town from an insulation supply house

 

[The Fallis]

Interesting Firebrick. That thought had crossed my mind for a mesh area somewhere for escaping air but never contemplated the entire sheet. Then although I'd then be concerned with water / humidity getting in through that side... Suppose I could lay plastic after.

I'm still unsure of the R value I would net. The walls may be ok as I can "dense pack" to an extent but the roof would be loose fill. I'm sure I can make up for pack with quantity as I have about 4' at the higher sections of the ceiling......

Wish someone had tried shredded extruded poly before...

 

[Radix2]

Interesting Firebrick. That thought had crossed my mind for a mesh area somewhere for escaping air but never contemplated the entire sheet. Then although I'd then be concerned with water / humidity getting in through that side... Suppose I could lay plastic after.

I'm still unsure of the R value I would net. The walls may be ok as I can "dense pack" to an extent but the roof would be loose fill. I'm sure I can make up for pack with quantity as I have about 4' at the higher sections of the ceiling......

Wish someone had tried shredded extruded poly before...

The material in those bags doesn't look shredded - chopped in to cubes maybe. If that is the stuff I would say it is useless, way too many voids in it and it wouldn't fill the corners at all - the final R value would be pretty low.

The best product for our environment is cellulose. Watch for the sales and Menards 11% days. Then you have a high performing end result that makes all your hard work in installing worth it.

 

[The Fallis]

There are two types they offer for pickup - Small cubes in 2"-4" squares and shredded. I would only use the shredded of course for smaller voids. if blown in with pressure I'm thinking it would tight pack fairly well. all up for debate. I believe I am going to attempt... the ceiling at least...

 

[Radix2]

I think the other thing to consider is that this stuff is probably very flammable. Don't know what that might mean if there was an insurance issue.

If trying to blow it in with air, I think it will be crazy with static electricity and will stick to everything. There must be reasons why the industry chose Fiberglas or cellulose since plastic beads are well known.

 

[bczygan]

Insulation works by creating tiny air pockets.

The spaces between these chunks of rigid insulation will be air leaks.

You will get insulation value, but far less than needed for that thin of a wall.

If you had a foot or two, I would try it. But not 3 1/2".

Bill

 

[Michigan Mike]

Way back when I worked scaffolding on a job where the pipe wrappers were covering large tanks 40 x30 ? with a double layer of the two inch blue poly. They had to rip a bevel on every piece. The apprentice on the job collected waste from the rippings and took it home to insulate the attic in his house. Everybody thought it was a good idea. The only down side was the thought of what it would be like if the house caught on fire with the fumes that would be generated.

 

[The Fallis]

luckily it is a detached garage so I'm not very worried regarding the fire issue. Also the entire interior will be sheet rock. to prevent that as well.

 

[desmato]

Go dense pack Cellulose from Menards as others have mentioned. do the glue on fabric, blower rental is free with purchase and Cellulose IS a vapor barrier, bug/animal proof, fire retardant, GREAT sound barrier, recycled and the cheapest R value per $ vertical and horizontal, doesn't matter. you can also wetset it without the fabric but it requires a special "machine" and some skill/practice.

"the price is forgotten long after the value is remembered" or something like that. If it's worth doing, it's worth doing the right way (That one is mine) so don't skimp on your time and property. pack as much in the ceiling as you can afford since 80-90% of heat loss is through the roof.

Todd (Holly, MI)