Unheated Garages: Interior or Exterior Wall Paint

jsheridan

I want to start a discussion on whether unheated garage interior walls should be painted with interior or exterior, with a poll included. We've had two inquiries here and it seems the feedback is mixed. It matches the general info I've found elsewhere online, and haven't found a definitive rec on paint co websites. We have a consensus on paint and primer in one. I think we need a forum consensus here.

To me it's a no brainer, exterior. Even with limited exposure, they're still exposed to temperature extremes, which is all I need to vote yeah. I believe that's one of the key formula distinctions between interior and exterior paints.

Also, exterior flats must be forumlated to experience rain, which I'm sure interior flats would buckle under. So a finish more resistant to water and wipable would be a benefit in a garage.

Personally, I've painted a number of garage interiors over the years and the choice has never been a question. I talked to a paint store manager who agreed, he would never recommend interior for that purpose. It's not as if exterior is significantly more expensive, and you don't need top of the line for a garage. What's the sticking point? Why take the risk?

I made this a blind poll. I was tempted to make it public which would have show how each person voted. If you vote interior, please explain why. I really don't care, it's not my garage, but I'm curious.

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ToolSeeker

I go for the exterior for the reasons stated. Plus if you are some where that gets snow it will build up under the car then when parked in the garage melts leaving puddles of dirty water that is pretty easy to splash on the walls. I just think the Ext. would hold up better and why take the chance.

Brushjockey

If you want to be really cheap- go straight primer like 123....

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jsheridan

Tool, did you vote? Voting is at the top of the page.
Thanks
Joe

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jsheridan

Non-committal? Come on BJ, it's not politics or religion.

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ToolSeeker

I voted now sorry. I think primer would look ok for a while but not really any protection for when something needed wiped off. And might not look to good after a while.

ric knows paint

I didn't vote. I didn't vote 'cause I think your options are too limited. Personally, I believe there should be at least 2 more choices - option #3 should be "Situational" and #4 be "Does it matter?".

If I were to make a broad recommendation to repaint the walls in an unheated garage, I'd go with exterior. But not necessarily for the reasons you've stated. In terms of durability and lifespan, exteriors are better products...period (and please remember, I'm speaking generally - very generally). They are better products because of their higher resin content (relative to interiors), or more specifically, their ratio of (among other things) pigment to resin (PVC). A higher level of resin generally means a more sealed surface - which means more stain resistance and easier cleaning. Also, generally speaking, exteriors usually have the advantage over mold and mildew growth than do their interior counterparts...(generally).

BUT...the reason I may recommend an interior paint is due to those same features that seem to give the edge to exterior products. An interior product, with a higher PVC, is going to yield better hiding - quality interior paints hide better than do exterior products. Also, assuming we're discussing flat paints, interior products are gonna touch up better than exteriors...Why? Back to that PVC issue, most exterior flat paints aren't really flat - in fact many would be on the eggshell level if they were to be used indoors. Dead flat paints generally don't perform as well when exposed to rain, sleet and snow as do sheened products.

So - application versus longevity. Thus the "Situational" option.

But, did you notice I didn't mention which one will perform better in an environment of temperature extremes? Once dried and cured, will an exterior outperform an interior based solely on varying (to extreme) temperatures? I'm not sure that question can be answered definitively. The performance of a cured "interior" versus "exterior" resin is pretty much equal between the temperature range of -20 degrees F to +120 degrees F . (We're talking exposure to temp ranges and extremes only here - NOT exposure to direct or constant sunlight / UV rays).

I've mentioned before that there really isn't a great deal of difference between interior and exterior resins anymore. The ratio of pigment to resin, the types of pigment, common additives and rheology modifiers are just as important in determining a product's use designation (interior or exterior) as is the type of resin itself. Matter-o-fact, many companies (including SW & BM) commonly cross-label interior and exterior products (same product, different label) for reasons of the raw material management, inventory control and simplification....and this doesn't necessarily apply only to high end, top drawer products - Sherwin's Pro Mar 700 (a truly horrible product) is listed as an "interior/exterior product.

...and thus the reason for option "Does it matter?"

So...if I were to vote, I'd check all 4 options - Interior/Exterior/Situational/Does it Matter? But then, I'm also the one who wouldn't be so quick to label the Paint & Prime products as elaborate marketing BS either...

Gymschu

I voted EXTERIOR, although it's not for every garage. I ask the HO if they plan on cleaning cars or scrubbing the grill using a garden hose to do these tasks. And, of course, having a center floor drain to wisk away the water helps too. If they use their garage (especially in winter time) to clean or even to cut trim or if they use it as a pseudo-workshop, I like exterior on those walls. Just a tougher finish IMO.

Brushjockey

I was going to say what ric did, but he beat me to it! lol..

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Will22

Depends on the climate, on the environmental exposure. Interior paint would suffice for the most parts of the country , although exterior paint is probably a better choice where there is extreme climate change (especially in an unheated garage). I agree with Gymschu that exterior is better for a "working" garage.

Will22

Just a point to add, that products labeled "Interior/Exterior" are interior paints, which do not have mildewcide in them.

jsheridan

I know, right. He does it to me aaaaalllll the time!

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chrisn

me too

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jsheridan

Thanks Ric. We all bring our unique perspective to the forum. You, unlike most of us, understand what's in the cans we take for granted every day. I appreciate that. I have no understanding of or background in chemistry, and therefore have to keep it simple.

Steamy environment - bath paint or some form of sheen
Kiddies with PB&J on their hands - something washable
Naturally dark or small room - light color
Temperature extremes - an exterior finish

Very simple. And because I have a simple mind, I can't understand why some can be so intent on using interior in that kind of environment. Outside of chemical characterisitics of the two, is there something about using one versus the other that I don't grasp? It's not a personal decision. Temp extremes are not an interior phenomenon.

As a professional, I wouldn't take a chance. IF, something did happen, the customer could turn to me and say it's because I used interior, whether it truly is or not. And because it's such a gray area, I would end up with the responsibility. It's a cover your bases type of thing. I see zero difference between using the two, other than personal preference. And when it comes to performance or function, personal preference takes a back seat to professional judgement. Just saying.
Rock The Vote!

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jeffnc

Which is exactly why I wouldn't put flat paint in a garage to begin with - I'd use eggshell (or "matte" at a bare minimum). So the poll ought to be eggshell interior vs. exterior. That makes it a lot closer in terms of performance.

But it does raise the question of comparing apples to apples. If you really want a true flat finish in your garage, then you should use interior paint. You might want that purely aesthetically. Or, you might prefer touching up over cleaning, where flat has an advantage.

Other than that, I guess my next garage will be painted with exterior paint.