Detached Garage Insulation DIY failure!?!

[5ilver8ack16]

Hey.

I need some advice/reassurance I haven't made a big insulation/vapour barrier mistake on my DIY project over the weekend.

Basically decided to insulate my detached 21X22ft garage as I use it as a home gym, and the Edmonton/Alberta winter is upon us.

I used basic batt insulation, and OSB boarding to make it a cheap and cheerful workable space in sub zero temperatures. My issue, I took advice for a garage cabinet guy in the US to determine the order to install materials.

His advice - External Wall/Vapour Barrier/Insulation/OSB.

Reading around (yes i probably should have done more prior) the general format for a house insulation is External Wall/Insulation/Vapour Barrier/Drywall.

Now. Should i be worried about moisture build up?

As it is a detached garage, I thought that the humidity/temperature variance inside to out probably won't vary too much and therefore minimal moisture build up.

Any advice would be greatly appreciated. I don't really want to rip it all down and start fresh!

Thanks

[Ken07AOVette]

I built my house and garage, you are right, the vapor barrier is the last thing you put up before interior sheeting or drywall.

[Desert_Faux]

You dun goofed...

[Austin]

Insulation, vapor barrier, drywall or board

Not sure what part of the US he was from that would do it the order he suggested. You run the risk of where hot meets cold will create moisture -can form moisture and rot the exterior wall or insulation gets wet and sags or creates mold. You do not want mold

[bat119]

Is the space going to be heated 24/7 or just when you use it? I found turning the heat down to 10 C works better than shutting it off altogether that cement pad can take days to warm up again.
The vapour barrier goes on the warm side however where your at now I would run for the winter then check for moisture along the inside bottom of the walls in the spring.

[Dick284]

Vapour barrier goes on the living side of the insulation.
Always.

Or better yet do it in spray foam and quite worrying.

[5ilver8ack16]

Bugger!

Ok. The space will be warmed gently when in use, I'm not planning on heating 24/7.

Options now...

1) Start Again
2) Wait and see worry about it in Spring if moisture is found.
3) Apply a second vapour barrier - creating vapour barrier on both sides of the insualtion.
4) Leave it, drink whiskey and try to forget about it!

Side note... I'm planning on applying for infill for the back yard, build a small 2-3 place on existing land... this will likely involved knocking down the garage and creating another building footprint in approx 3-4 years time.

[big zeke]

The vapor barrier goes on the "warm in winter" side of the wall hence you have it backwards. You mention that you used OSB so taking it down shouldn't be too bad, much easier than if you used drywall and you can re-use the sheets.
My suggestion, take down the OSB one wall at a time, pull out the batts, tear out the vapor barrier that is against the outside walls (I'd be concerned that it could trap any moisture from the outside), then reinstall the batts, install the VB and screw the OSB in. If you do a wall a day you will be done later this week. If the labor is free, the total cost will be like $50 in VB and you'll be a lot smarter for the next time.
Make sure to Tuck tape any joints, the barrier has to be continuous.

Good Luck.
Zeke

[Bitumen Bullet]

Originally Posted by 5ilver8ack16

Bugger!

4) Leave it, drink whiskey and try to forget about it!

Side note... I'm planning on applying for infill for the back yard, build a small 2-3 place on existing land... this will likely involved knocking down the garage and creating another building footprint in approx 3-4 years time.

I like #4 but am pretty sure it's going to start getting moldy at some point so I'd be really sure about knocking down the garage in a few years before committing to it.

IMO Garages are the worst when it comes vapour barrier. We are told that the moisture barrier is on the outside and vapour barrier on the inside but that is really just the case for houses and areas that are heated 24/7.

If the area is not going to be heated all the time, or has other issues (dirt floor for example) then the vapour barrier becomes a bigger issue, moisture becomes a bigger issue, because it will be heated there will be moisture. Even unheated areas can have moisture problems, so it's always a concern.

If not #4 I would consider putting plastic on the inside, if I thought I could seal it completely and/or put a dehumidifier in there (can also double as a heater). Of course for the dehumidifier to work the place will have to be heated to around 10C (or something like that check instructions) but I have had some major success controlling moisture with cheap dehumidifiers and they are much easier to set up than trying to correct building issues in the winter.

Speaking of moisture control if I was trying to put that off until next year I would put some temperature probes in the wall by the vapour barrier, maybe even a hydrometer probe, in the faraway corner, down near the bottom of the wall. A cheap remote thermometer with external probe can be had for about $25. With temperature and humidify information you can determine how much of a problem condensation is going to be.

Another option is to put in a small cheap single pane window. Keep it free of condensation and chances are the walls will be fine.

BTW I think foam is the best but not if it is coming down in a few years.

[5ilver8ack16]

Thanks Bitumen Bullet!

I'm thinking #4 could be the best option. Failing that... Would I be causing more of an issue if i installed a 2nd vapour barrier behind the OSB.

Thus my setup would be...

External Wall/Vapour Barrier/Insulation/Vapour Barrier/OSB

Floor is still standard concrete slab.


Might be overkill... but seems like a good way to go, and not tear down a weekend of work...And with highly likely possibility of knockdown/property sale in maximum 5 years.

Honestly, we have been in the house 6 months and i haven't noticed any moisture issues in the garage... just bloody cold, so wanted to try warm it up for -40c and training in my garage gym.

[Clgy_Dave2.0]

Originally Posted by 5ilver8ack16

External Wall/Vapour Barrier/Insulation/Vapour Barrier/OSB...

= a "moisture sandwich".

That'd be worse than what you have currently.

[Moo Snukkle]

I'll take no insulation over dual vapour barrier (against code).

[Bitumen Bullet]

Originally Posted by 5ilver8ack16

Would I be causing more of an issue if i installed a 2nd vapour barrier behind the OSB.

Floor is still standard concrete slab.

Honestly, we have been in the house 6 months and i haven't noticed any moisture issues in the garage... just bloody cold, so wanted to try warm it up for -40c and training in my garage gym.

Add my name to the list thinking the moisture sandwich will be troublesome, actually I'm sure it will be, partially heated garages are not easy when it comes to moisture control. If you could actually seal the inside plastic (harder than it sounds) it might not be too bad for a few years but you would still want to monitor for moisture (maybe even vent) as it will get into the walls from the top, bottom and the many places not sealed during install.

By the time you notice moisture issues they can be huge and can cost a lot of money and effort.

I'd still go with #4, heat it, maybe dehumidifier, and then go back and do the job proper next summer. BTW you may be shocked at how much water damage occurs over that short time if you completely ignore the issue.

And when it comes to resale IMO you really should do it properly. Chances are you won't notice the moisture problems until a potential home buyer spots something or smells the mold. At that point you'll really wished you had fixed it when everything was new and not moldy. Mold can knock thousands off the price because the new buyer has to consider ripping everything down to studs and starting over with all new materials.

[pikergolf]

I wish people would speak to building inspectors. Free pertinent advice.

[Bitumen Bullet]

Originally Posted by pikergolf

I wish people would speak to building inspectors. Free pertinent advice.

Yep, of course it's often it's like asking electricians about a specific grounding issue. "It's right here in the code book....." "Except for this exception here....". "The inspector in that area wants...." "We've always done it this way...". Fun to watch unless you are the one wanting an answer.


But in this case I'm betting most would say don't delay open it up and do it right. Which is pretty much the first answers given.

[Twisted Canuck]

You've heard it already, but you need to fix it. Simplest way to say it is vapor barrier goes on the warm side of the insulation. The way it is, you will have moisture issues, your insulation will get saturated regardless of how little you heat the space, and then you lose your R value and will have mold issues. DO NOT sandwich vapor barriers on both sides of insulation. Just asking for major moisture/mold issues. Best thing is tear the OSB off, pull out batts, take out Poly, and do it correctly. A huge pain in the butt, the alternative is worse. Just my two bits, but I would not leave it like that and hope for the best. In our climate, with such huge temperature swings season to season (+30 to -30 C) with a relatively high humidity in some seasons, you have to do it right.

[TBD]

depending on when that garage was built (at least in calgree anyways) the use of osb sheeting may not meet code. Something to check.

not good if you have a fire and try to collect insurance - I know I know - lots of details. welcome to the world of regulations.

I fear in the future it will be harder and harder (due to building codes and liability) for home owners to do these projects for themselves.

[Clgy_Dave2.0]

Originally Posted by TBD

depending on when that garage was built (at least in calgree anyways) the use of osb sheeting may not meet code. Something to check.

Huh?

Source?

[Grizzly Adams]

Originally Posted by pikergolf

I wish people would speak to building inspectors. Free pertinent advice.

Any lumber yard employee would know this. In the old days they never worried about vapor barriers and the houses are still standing. Mistake was made, live with it.It's only a garage. Good coat of paint would cut down on moisture as well.

Grizz

[TBD]

Originally Posted by Clgy_Dave2.0

Huh?

Source?

Straight from the Safety Codes Officer...

AB Building Safety Codes
Article 9.35.4.1 Interior Finish
12.7mm thick gypsum board, or lathe and plaster conforming to subsection 9.29.4 or any material that can prevent the passage of flames when subjected to the standard fire exposure and CAN/ULC-S101. (fire endurance test of building construction or material)
So from that I guess you just need fireguard OSB to be good? Know parkland county for one does not allow OSB inside a garage, got a notice that a garage failed inspection, because owner put OSB inside.


I think it was 2010 .... not absolutely sure you'll need to do some research on this if you're not up to date

insurance companies are looking for absolutely any reason they can come up with to deny you insurance these days.

I know if it was my garage, factoring in how much I have invested in tools, I would make doubly sure interior osb finishing is allowed by code in my area.


.

[Clgy_Dave2.0]

Originally Posted by TBD

Straight from the Safety Codes Officer...

AB Building Safety Codes
Article 9.35.4.1 Interior Finish
12.7mm thick gypsum board, or lathe and plaster conforming to subsection 9.29.4 or any material that can prevent the passage of flames when subjected to the standard fire exposure and CAN/ULC-S101. (fire endurance test of building construction or material)
So from that I guess you just need fireguard OSB to be good? Know parkland county for one does not allow OSB inside a garage, got a notice that a garage failed inspection, because owner put OSB inside.


I think it was 2010 .... not absolutely sure you'll need to do some research on this if you're not up to date

insurance companies are looking for absolutely any reason they can come up with to deny you insurance these days.

I know if it was my garage, factoring in how much I have invested in tools, I would make doubly sure interior osb finishing is allowed by code in my area.


.

That's code for an attached garage (Or, IIRC, a detached garage with a dwelling above it). OP has a detached garage.

The walls and ceilings of an attached garage shall have an
interior finish consisting of
a) not less than 12.7 mm thick gypsum board
conforming to Subsection 9.29.5.,
b) lath and plaster conforming to Subsection 9.29.4., or
c) any material that can be shown to remain in place
and prevent the passage of flames for not less than
15 min when subjected to the standard fire exposure
in CAN/ULC-S101, “Fire Endurance Tests of
Building Construction and Materials.”

[220 Swift]

If you find it getting damp an exhaust fan could be installed to pull moisture from inside. This is the actual purpose of a bathroom fan not just for farts.

[TBD]

Originally Posted by Clgy_Dave2.0

That's code for an attached garage (Or, IIRC, a detached garage with a dwelling above it). OP has a detached garage.

yeh my garage was attached, missed that.


thanks Dave !



PS ... dodged a bullet there silverback

[tiger woods]

Originally Posted by Twisted Canuck

You've heard it already, but you need to fix it. Simplest way to say it is vapor barrier goes on the warm side of the insulation. The way it is, you will have moisture issues, your insulation will get saturated regardless of how little you heat the space, and then you lose your R value and will have mold issues. DO NOT sandwich vapor barriers on both sides of insulation. Just asking for major moisture/mold issues. Best thing is tear the OSB off, pull out batts, take out Poly, and do it correctly. A huge pain in the butt, the alternative is worse. Just my two bits, but I would not leave it like that and hope for the best. In our climate, with such huge temperature swings season to season (+30 to -30 C) with a relatively high humidity in some seasons, you have to do it right.

To the OP, sometimes trying to weed through the advice on an open forum like this can be difficult with all of the opinions that get thrown about.

This gentleman has nailed it for you. If there is one reply that you take into consideration, it should be this one.

The science behind it has to do with wherein the dew point lies within your roof or wall system, which will change depending on the outdoor and indoor temperatures. That's the coles notes version anyways.

Long story short, double vapour barrier is a no go. As is leaving it and hoping for the best. Unfortunately, if you want an insulated garage then you will have to do everything again, this time with the vapour barrier on the warm side (interior side) of the insulation. Wish I had a less labour intensive answer, but I can promise you that if you do it this way then you won't have to do it a third time.

[wildwoods]

Originally Posted by tiger woods

To the OP, sometimes trying to weed through the advice on an open forum like this can be difficult with all of the opinions that get thrown about.

This gentleman has nailed it for you. If there is one reply that you take into consideration, it should be this one.

The science behind it has to do with wherein the dew point lies within your roof or wall system, which will change depending on the outdoor and indoor temperatures. That's the coles notes version anyways.

Long story short, double vapour barrier is a no go. As is leaving it and hoping for the best. Unfortunately, if you want an insulated garage then you will have to do everything again, this time with the vapour barrier on the warm side (interior side) of the insulation. Wish I had a less labour intensive answer, but I can promise you that if you do it this way then you won't have to do it a third time.

x3 listen to this advise.
I'm wondering how the heck you got the poly on BEFORE insulating in the first place...
But yes, please don't chance it. Don't double vapour barrier it (huge moisture trap). Tear it out and do it again. There will be some very inexpensive labour to have if you look hard enough. Perhaps hiring a handyman for a day will ease the pain of re-doing it all on your lonesome...
Way to swallow the pride and ask though. There's value in that.

[wildwoods]

Originally Posted by Clgy_Dave2.0

= a "moisture sandwich".

That'd be worse than what you have currently.

Originally Posted by Moo Snukkle

I'll take no insulation over dual vapour barrier (against code).

this^^^^

[Grizzly Adams]

Originally Posted by TBD

yeh my garage was attached, missed that.


thanks Dave !



PS ... dodged a bullet there silverback

Not a garage anymore either, it's a Man Cave.

Grizz

[elkhunter11]

Invest some labor now and redo the insulation/vapor barrier properly, or do it later while likely having to deal with a mold issue. The weather is nice now, don't waste it trying to avoid doing what you know you need to do.

[Kim473]

Vapor barrier always to the warm side. Redo it now while it's warm.

[HyperMOA]

This is why I am so scared to buy anything used. So you put a grand of insulation up, and do the job incorrectly. Just to save a few bucks. Which I can understand. Then instead of making the effort to resolve the issue you say you will likely sell it in 5 years. At that point you will want the realtor to reflect the price of an insulated garage. The new owner then has to tear down the walls and replace all the insulation. Have mold abatement done. Then they have to pay to dispose of the materials. Then they have to buy new insulation and vapour barrier. Then they have to install or pay for it to be installed. All of this for something they already paid you for!!! Tear it down and do it right. Next time you DIY make sure you know what to do.

It must've been really fun vapour barriering around all of those studs. At that point you should've stopped and realized how dumb the process was. Once you do it the right way you will see how really easy it should be.