Insulation for Under my Brew House?

My brew house is about 200 sq ft on the floor and up on pilings. I need to insulate underneath as there is currently nothing there. The guy I bought my house from built this as a taxidermy shop and for some reason didn't go through the trouble. The walls and ceiling are insulated.

I've been doing some online research and there are lots of different recommendations. I thought some of the contractor type people here might have an answer.

This was the most involved I've found.
1) staple a vapor barrier btwn the joists.
2) push R18 un-backed insulation btwn the joists
3) cut 2" Pink foam board and place snug between the joists
4) use furring strips to hold in place
5) cover entire area with 1/4" wire mesh.

This was the easiest I've found:
1) Push R18 Backed insulation (with the backing toward (also read away) from the floor)
2) Hold in place with furring strips.

How serious should I go here? Do I use Backed or Un backed insulation? Which way should it face? There are so many conflicting opinions out there.

Thanks!
-Karl

I'd pull the floor, stuff the soft stuff down between the joists proper side up, nail flooring back down. I am not a contractor

Floor is already down and tiled...I did that all last October.

I can access underneath by crawling under the brewery since it is up on pilings. It's definitely going to be messy, but I'll fit. I'm just confused as to using backed/un-backed and what orientation (up or down) it needs to face.

Here is a photo of the brew house....

https://cdn.homebrewtalk.com/gallery/showphoto.php?photo=39569&limit=recent

the back side is significantly higher off the ground allowing easier access. After I get the insulation installed I plan on putting lattice around the bottom to cut down on the wind blowing through and attempt to keep the ground hogs out. =)

Shouldn't the insulation tell you? I'd imagine it'd be printed on the actual paper backing as to which side should be up.

why not spray in insulation, You could spray in foam or cellulose. This way you wouldnt have to rip open the walls.

It doesn't really deal with buildings up on pilings. It specifies paper up (or towards floor) for "vented crawl spaces" but I don't know how this applies to my situation. I know it has to do with vapor transmission and air flow. One site even recommended unbacked and then poly sheeting stapled to the joists. It seems there are many ways to skin this cat, just trying to make sense of it all.

JewBrew said:

why not spray in insulation, You could spray in foam or cellulose. This way you wouldnt have to rip open the walls.

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The cellulose stuff I saw is not designed to "stick". It's more for attics.

I just need to do the floor from underneath so i need a way to attach it. I could use a spray foam, but I believe this is pretty costly and would probably have to pay someone to come in with the machine.

From what I have read, the vapor barier should face the heated space otherwise, condesation can occur within the insulation and rot the structure.

I did a similar thing under an addition on my house. I stapled plastic between the floor joists and to the underside of the subfloor. I then used unfaced insulation between the joists and 2-in rigid foam nailed to the bottom of the joists.

lschiavo said:

From what I have read, the vapor barier should face the heated space otherwise, condesation can occur within the insulation and rot the structure.
...

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That is right on the money. The vapor barrier must be installed facing the conditioned space.

Ischiavo, Did you also staple more plastic over the rigid foam or just left the foam exposed? It sounds like nailing these in place held the insulation and you didn't need furring strips.

Also, if I use the backed insulation (against the heated space) could I skip stapling plastic first since the backing acts as the vapor barrier?

Thanks for your help guys!

BentTwigBrew said:

Ischiavo, Did you also staple more plastic over the rigid foam or just left the foam exposed? It sounds like nailing these in place held the insulation and you didn't need furring strips.

Also, if I use the backed insulation (against the heated space) could I skip stapling plastic first since the backing acts as the vapor barrier?

Thanks for your help guys!

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I only used the plastic against the subfloor. You dont want a double vapor barrier. I used unfaced insulation because I happened to have it. I held it in place temporarily with drywall tape stapled across the joists until I added the rigid foam.

I am sure a backed insulation would work just as well. You may want to add some covering (screen) over the foam to protect from rodents if you think this may be an issue. I haven't gotten that far yet.

Have fun! Insulating has always been a joy for me (read the sarcasim). It is especially enjoyable laying on your back in the dirt

I recently insulated my crawlspace and wanted to confirm the vapor barrier toward the floor. I would skip the plastic; the rigid foam will act as another vapor barrier - be sure to seal those joints to achieve the barrier.

Roger that

1)Backed insulation with backing towards the subfloor between the joists.
2)Rigid foam (pink stuff) between the joists
3)Sealed joints in foam to achieve the barrier
4)Screen over foam to keep critters out.
5)Drink lots of homebrew cause this project will suck...

All in favor?

I'd at least get an estimate for having someone spray in the insulation and then proceed to step#5 and watch them do it. Times are tough and someone just might want to fill in a day with a quicky job - maybe the promise of 5 gallons of homebrew to sweeten the deal.

BentTwigBrew said:

Roger that

1)Backed insulation with backing towards the subfloor between the joists.

2)Rigid foam (pink stuff) between the joists
I fastened the foam to the bottom of the joists with the long washer nails. I did not cut it to fit between the joists. This may not work in your situation but will save a lot of cutting if it does.

3)Sealed joints in foam to achieve the barrier
I dont think this is desired as the vapor barrier is against the subfloor. You want your fiberglass to be able to breathe a bit.

4)Screen over foam to keep critters out.
5)Drink lots of homebrew cause this project will suck...
Correct!

All in favor?

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*

samc said:

I'd at least get an estimate for having someone spray in the insulation and then proceed to step#5 and watch them do it. Times are tough and someone just might want to fill in a day with a quicky job - maybe the promise of 5 gallons of homebrew to sweeten the deal.

Click to expand...

I just got a quote from 1 guy. He wants $1500 for the job! I could get the material (for 3" of closed cell foam) and spray kit for about $610 + shipping and do it myself.

https://www.sprayfoamdirect.com/pro...facturer_id,0/option,com_virtuemart/Itemid,1/

http://www.betterenergystore.com/productpage.asp?p=4

If I did only 1" thick I could do it for about $330 but that is only R7. I requested some other quotes...we'll see what comes back.

I think fiberglass is significantly cheaper...I'm not sure if it even makes sense to spray foam the bottom of the brew house if the rest is normal fiberglass insulation.

If it were me, I'd do 1/2" rigid foam under the subfloor OR staple 6mil plastic between joists as vapor barrier. Absolutely the vapor barrier faces the conditioned space in the North states. Fill the whole cavity with unfaced fiberglass, use those push in wires to hold it up (they are like 15" long and have to jam between the 16 o.c. joists. Finish off by stapling a full piece of wiremesh.

Bobby M to the rescue =)

I have a HUGE roll of Military grade vapor barrier that we were throwing out @ work. I rescued it. I can use that btwn the joists then use unfaced fiberblass with the pins and follow with the wiremesh. This sounds like the most cost effective way to get this done.

You seriously need to consider putting something solid or at least critter-proof to protect the insulation. I have a crawl space and insulated with 6" batts. There's a nice layer of shredded pink all over under the house. Rodents love the stuff.

And Boss loves rodents. Got 5 ground squirrels this year.

david_42 said:

You seriously need to consider putting something solid or at least critter-proof to protect the insulation. I have a crawl space and insulated with 6" batts. There's a nice layer of shredded pink all over under the house. Rodents love the stuff.

And Boss loves rodents. Got 5 ground squirrels this year.

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Very true

My house was built in the early 60s as a summer river cabin, with a bedroom, laundry room addition added on in about 69 or 70.

When I found this place I inspected it top to bottom. There was no insulation in the crawl space, ether side. I insulated the original half that fall. I didnt get around to the bedroom laundry room at this time had some remodeling plans.

The next spring I start my project so I crawl in to the original half of the house what do I find rat **** there was none when I insulated. Now I go into the uninsulated half clean as a whistle. Call the exterminator he comes out and i get a schooling on rats. Long story short the insulation cost me 400$ I installed it. It cost me 1500 to remove it. Haven't had a issue in years.

Rats are like rabbits they will dig deep under foundations down to 6 or 8 feet.

good lookin out...my house is practically in the woods so I get a lot of critters back there. I hope a metal mesh should keep them out. I'm going to attempt this on Sunday (hopefully) I'll keep you posted at to how it goes.

My cat is a pretty good mouser, but he has his paws full just keeping them out of the house.

Down here, the pro's recommend you do not insulate the floor space. They say to insulate around the perimeter with styrafoam. About 85% of houses around here are built on crawl spaces.

It is wide open on all sides so there is no perimeter to insulate. I'll probably do what you recommended in my house where I have a crawl space though...so many projects, so little time

and $