Garage Insulation Options

[Muliemaster]

Hey,

I have a 20x24' 8ft detached, unheated garage. It will be heated soon, when funds become available!!

Its is open to the roof right now, with just the trusses spaced at 24". I would like to get the insulation all done before I get the heater in there. I have a propane space heater which will suffice for now. Have any of you guys done spray insulation? How is your cost? Rough calcuations give me 550sqft. I have only 1 quote and it was $3.20/sqft, leaving me with a $1800 bill!!! too much for me. I priced out just putting Roxul batts and vapor barrier in for about $400. I know they don't seal as well to wind but it is a garage and about 1/5 the cost.

The walls are concrete about 4' high and the other 4' are insulated already.

Thoughts?

[nick0danger]

I personnly wont do spray foam, i burn like not other even the ones that are not suppose to. Try it.

[Reeves1]

Originally Posted by nick0danger

I personnly wont do spray foam, i burn like not other even the ones that are not suppose to. Try it.

Any code breakers here ? I don't have an enigma machine handy.

[CaberTosser]

Originally Posted by Reeves

Any code breakers here ? I don't have an enigma machine handy.

I have one in the U-boat we captured in the cee-ment pond out back. I'll go get it.

"I personnly wont do spray foam, i burn like not other even the ones that are not suppose to. Try it."

" I personally won't do spray foam. It burns like no other; even the ones that are not supposed to. Try it."

As for the garage insulation, while spray foam is nice (I put it in my own house), the extra cost payoff from spray foam would be a little longer for a garage than for a house, especially if you only heat it as a workshop sporadically. Normally a garage is kept at a lower temp than a house, so it is subject to less heat loss as a result, due to the lower overall temperature difference. Are your walls 2 x 4 or 2 x 6?

[7 REM MAG]

lots of guys are going to rigid insulation glued with i believe pl5000 its a regular tube with blue lettering and it doesnt eat the foam, anyhow apply glue to the insulation in a back and forth pattern that will end up looking like lots of "S"s dont run a bead all the way around the piece of insulation or the pl wont cure properly, once the insulation is all done pl the seams so that it is completely sealed and you dont need to vapour barrier, at r-5 per inch you will get either r17.5 or r27.5, min code for a house is r20 not sure what it is for a garage but you will have plenty of heat retention, if you want to effieiently heat your garage seal the ceiling and get some blown-in insulation up there and your garage will be good to go with a relatively small heater

[Muliemaster]

Originally Posted by CaberTosser

IAs for the garage insulation, while spray foam is nice (I put it in my own house), the extra cost payoff from spray foam would be a little longer for a garage than for a house, especially if you only heat it as a workshop sporadically. Normally a garage is kept at a lower temp than a house, so it is subject to less heat loss as a result, due to the lower overall temperature difference. Are your walls 2 x 4 or 2 x 6?

2x4

This is sort of what I was thinking as well. I just got another quote today, $1100. Much more reasonable, 1.5" of 2lb foam.

The garage is going to be a workshop, I really don't need constant heat in there. I was thinking of an overhead forced air ng blower. I'd just like heat for when I need to work on the truck or decide to do a little woodworking and whatnot. I sure won't be out there when its -30!

The only thing I've heard and read about spray foam is the wind barrier it creates. Guess I could maybe go nuts with the vapor barrier and tuc tape.

[Muliemaster]

Originally Posted by 7 REM MAG

lots of guys are going to rigid insulation glued with i believe pl5000 its a regular tube with blue lettering and it doesnt eat the foam, anyhow apply glue to the insulation in a back and forth pattern that will end up looking like lots of "S"s dont run a bead all the way around the piece of insulation or the pl wont cure properly, once the insulation is all done pl the seams so that it is completely sealed and you dont need to vapour barrier, at r-5 per inch you will get either r17.5 or r27.5, min code for a house is r20 not sure what it is for a garage but you will have plenty of heat retention, if you want to effieiently heat your garage seal the ceiling and get some blown-in insulation up there and your garage will be good to go with a relatively small heater

Definitely an idea to use the rigid board. I believe since the garage is detached, there is no code for insulation. Seems like almost as much effort as putting batting up there and vapor barrier after... I bet it would almost hold itself in with the nails which poke through the roof from the shingles!

[pikergolf]

Originally Posted by Muliemaster

Definitely an idea to use the rigid board. I believe since the garage is detached, there is no code for insulation. Seems like almost as much effort as putting batting up there and vapor barrier after... I bet it would almost hold itself in with the nails which poke through the roof from the shingles!

Umm, the insulation is going between the trusses flush with the ceiling and not up against the roof right?

[CaberTosser]

They can spray the roof if they tack up insulation stops through the whole thing first. Parts of my attic were done like that, the rest will be sprayed against the ceiling drywall once that's in.

[7 REM MAG]

he said he has open trusses so he either needs to sheet his ceiling or insulate the underside of his roof sheathing, like i said more efficient to sheet the ceiling and insulate that but cheaper in the short term to insulate the underside of the roof

[pikergolf]

He said the trusses are "open for now", so I guess the question is what exactly are you intending to insulate? The roof or the ceiling?

[CaberTosser]

Ahh Mulie, I just noticed it was you that made that comment about putting rigid foam board up against the bottom of the roof sheathing, letting the shingle nails hold it up. I'm not sure if you were kidding there or not, so I'll note that the insulation can't go right to the bottom of the roof sheathing. There needs to be an airspace there for airflow to keep the roof sheathing dry. Problems arise if no airflow exists there, some of which can be ice damming and the sheathing rotting, among others.

If you were kidding. HaHa, carry on.

[Muliemaster]

Thanks for the responses!

Guess I should have clarified myself better. The roof is currently open, I would like to keep it open. Since its only an 8', I want to keep it open to gain the extra storage space - So I would like to insulate the roof, not the ceiling. Even little things like hanging a deer, the extra open trusses are nice so the legs can stick through the opening. I am also into woodworking so its nice for longer stock storage.

[Muliemaster]

Originally Posted by CaberTosser

If you were kidding. HaHa, carry on.

I was, I was. My internet sarcasm is something to be desired...

[buzzard]

The best bang for your buck is just insulate the rafter spaces with roxall or fiberglass. The toughest part will be installing the vapor barrior, with the use of acustic sealant an tuctape. Sprayfoam would be the easiest,fastest probably the best but the most expensive.

[pikergolf]

roxul fits a little tighter than glass and it has a little more insulation value. I would find out about, how far down the roof to install it and find out about eaves venting and whether or not you can close them off. I would guess that you can close them off but not sure how far down the roof you can run the insulation. One of the things we never covered in apprenticeship and have never run across. If in doubt call a building inspector, free advice

[maddwapper]

you could place batts of fiber glsss between rafters ,,with 1x4 2 ft centre tohold in place ,,but you need an air space between sheeting and insulation ,,so you could fur out your rafters to about 8 ins ..more work but better job /and easier to finish later R 20 insulation not up to code but efficient

[kodiak4x4]

Go with the Roxul, it resists mold, rodents, insects, and will withstand a hellm of a lot of heat from fire. I did mine (22x24) and used 3/8" OSB walls and have a 45000 btu heater in there, I can work out there even if it is -30. Use a minimum r20 in the attic and r12 in the walls and you'll be fine. Just my 2 cents

[rhuntley12]

Originally Posted by kodiak4x4

Go with the Roxul, it resists mold, rodents, insects, and will withstand a hellm of a lot of heat from fire. I did mine (22x24) and used 3/8" OSB walls and have a 45000 btu heater in there, I can work out there even if it is -30. Use a minimum r20 in the attic and r12 in the walls and you'll be fine. Just my 2 cents

Is yours metal sided? Just had a pole barn put up and my next project is insulating it and from what I understand between the metal and insulation needs to be a vapor barrier, is that what you did? (Ours looks like the picture on http://www.goodon.com/ so going to put vapor barrier attached to horizontal beams, then insulation, then the wall panels.

[Muliemaster]

no, its just wood sided. Just your generic inner city, detached garage. Plastic siding on the outside.

I'm a little slow on the uptake today - so I can put roxul between the upper cords? It will end up touching the underside of the roof - then tack up my vapor barrier next. Does this provide enough dead air space? or do I need more air space?

I guess another option would be to tack up 1x4 or 1x3 onto the bottom side of the upper cords and then glue the hard board insulation to it?

I'll have to look into the airspace for the soffets. Not sure what a detached garage needs. More digging.

[CaberTosser]

You need about 11/2-2 inches for air movement in there. Look at the cardboard insulation stops, they're made to fit between the trusses. They have creases where you can fold them, and that creates the airspace necessary. Usually you'll have to cut a few with a razor knife, but most should
fit as is.

[Ice Fishing Maniac]

I just had my garage built this summer/fall 24x28x10'walls. 2x6 framed. We insulated the walls with R20 and had the attic area sprayed in....R40 value (about 17-18" thick)-cost was around $700 for the spray-in. My radiant heater is not installed yet (was suupose to be last week) but with just the heat from the vehicle's motor keeps the garage ok right now.

[bootneck]

Hi there

I recently insulated the walls and ceiling of my att garage similar to you, I used batts between the joists and then covered it with vapour barrier with the intention to finish it off with plaster board when funds allow.

However, in the recent -30ish cold snap Ive noticed a small build up if ice along the bottom edge of the concrete and vapor barrier which I presume is from melted snow from the cars and the heat from engines warming the garage slightly.

Im glad I didnt board over the walls now or i'd never know what was going on, it seems I have created an airtight space so the moisture cant escape. Im considering taking part of the polly sheeting of so the garage can breath a little.

Any thoughts ?

Paul

[Kim473]

Use fiber glass batt. Put 3/8 plywood above the joists and go between the the trusses with it, make a 4 X 2 foot opening for your access up there and you will have plenty of storage and a spot for your deer legs to go up when hanging. Put the insulation up then 6 mil poly then 3/8 plywood up. the garage will be warmer this way as less room to heat as heat rises. You will have plenty of storage up there and if you go between the joists with ply wood you can get large plastic covered boxes that will fit between also. 3/8 plywood is the cheapest. About 1/2 price of drywall. Dont forget to do all your electrical first and put a couple of lights and a switch in up there. For the attic hatch you can get a pc of old insulated alluminum both sides garage door. Check with Barco doors or creative doors. They should have an old pc from a commercial job that they redone. From the bottom up you will have:
plywood, poly, insulation, plywood. Buy yourself a drywall lift from princess auto on sale. It makes putting the plywood up very easy. Only about a hundred and fifty bucks and when done sell it to someone else or put an add in to buy a used one. The best thing you would have bought since sliced bread. Its not commercial grade but very good for a garage.

[Jiffy10]

If your keeping the rafters exposed for storage etc. you are very limited
on what you can do. SPray Foam is the best and in the long run you should
consider investing in it now. Bat insulation will have LOTS of exposed
cracks / seams on every joist in the ceiling and at every place where 2
pieces meet. In reality... if you thing your creating an R value of 20
you are actually getting 10 after all the heat escapes. Becuase of the
risk of moisture in a Garage with the opening and closing of the doors etc.
your insulation has to be moisture proof also. The answer again is spray foam.
Even the styrofom sheets will have TONS of heat loss between the joints
and rafters so again..... its a bad investment. One alternative is this..
Call Northland construction. They sell the large orange insulated Tarps
that they use all winter in the construction sites. They are fairly reasoable
and you can get them in approx. sizes of what you need. IE one tarp
for each side of your roof. YOu can overlap them at the peak inside and
tape the one seam that may loose some heat. Its the next best thing to
spray foam. Check it out .... ps. these tarps make the best material
for ice shacks ! insulated for warmth... you can heat your hut with a candle and never have moisture.

Stay warm ...

[spazzy]

What did you end up going with ?? Im in the same spot as you were dont want to close in the ceiling . Im considering spray foam any ideas ?

[250mark1]

did R22 roxul in my garage walls 2x6
and had R50 blow in fiberglass insulation in the garage i built this year
30x24 x 12ft wall

[skidderman]

I desperately wanted to keep my rafters open for storage so I cut & placed 2 inch foam and put it up tight against the sheathing. Huge mistake. Have to take it all down & go to plan B. The idiots that built my garage have solid lumber on the eaves so adding ventilation is a problem. Don't know what I will do but this is no good. Just a heads up!!!!

[mattthegorby]

Originally Posted by maddwapper

you could place batts of fiber glsss between rafters ,,with 1x4 2 ft centre tohold in place ,,but you need an air space between sheeting and insulation ,,so you could fur out your rafters to about 8 ins ..more work but better job /and easier to finish later R 20 insulation not up to code but efficient

The airspace that a couple have mentioned is critical for condensation unless you are going spray foam. Air needs to flow from the eaves through the ridge. Hopefully you have rafters, I have furred these out before, but would imagine a 2×4 truss would be a nightmare to do a good job and poly.

Matt

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[skidderman]

Originally Posted by mattthegorby

The airspace that a couple have mentioned is critical for condensation unless you are going spray foam. Air needs to flow from the eaves through the ridge. Hopefully you have rafters, I have furred these out before, but would imagine a 2×4 truss would be a nightmare to do a good job and poly.

Matt

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Are you suggesting that if one had a perfect seal then air circulation is not required? Was told that as well but don't know what to think.