Should I insulate my garage?

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RandomPointer
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Should I insulate my garage?

Post by RandomPointer » Fri Apr 13, 2018 1:42 am

I have an attached unfinished garage. The wall between the living space and the garage is well insulated.

I have been considering to finish my garage. I have been researching whether I should insulate my garage or not, and I do not have any idea.

My garage is very hot in the middle of Summer, and very cold in the middle of Winter. I live in PNW, and I don't ever remember water in my garage got frozen. I store a lot of things in my garage, and it also have a freezer, a water heater, and a furnace. I do not plan to heat my garage.

I would like to know if it is worth it to insulate my garage or not, or just put the drywall and be done with it. I am concern that putting insulation to the garage wall and ceiling will just waste my money.

Any idea?

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just frank
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Re: Should I insulate my garage?

Post by just frank » Fri Apr 13, 2018 4:11 am

Yes. Not a super high priority, but a nice feature.

I upgraded the insulation in my garage, taking it from the 40s in the winter to the high 50s. Mine is a 'tuck under', so it has a lot of house contact area, and not much outside wall area. YMMV.

--You should carefully airseal between the garage and the house...you do not want carcinogenic car exhaust getting dumped into the house. Studies have shown that in houses with attached garages, much of the indoor air in the winter is drawn from the garage (the builders are often careless sealing between the two spaces b/c the garage is 'inside') AND that much/most of the indoor pollution (CO, benzene, ozone) comes from the garage and car. This sealing also reduces insects/vermin in the house a lot (they often go to/from the garage for water, prey, etc). This is a weekend project with a few tubes of caulk and spray foam, and can save you money on your heating bill....and might also keep you healthier.

--I also installed a blower to vent my garage to the outside 24/7 at about 15 cfm. This creates a slight negative pressure, in addition to venting any car exhaust or fuel vapors...further reducing indoor pollution.

--My garage doors were uninsulated...and from 1960. I added some foamboard to them.

--I had a mix of concrete and stone walls. Stone conducts heat much better than concrete, so I put some foamboard over the stone walls.

It is much nicer having a 55° garage in December than a 40° one. The garage stays drier, snow melts off the car faster, more comfortable to be in the car before it warms up, etc.

Lastly, if your hot water heater is electric, you can save $300/year by switching to a heat pump water heater, maybe $200 in the PNW. This only makes sense if the garage spends most of the year above 45-50°F. The HPWH will dehumidify the space (for 'free') and drop the temp a couple degrees on average, but otherwise its free money (often with rebates from the power company) and an energy savings.

bigdav160
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Re: Should I insulate my garage?

Post by bigdav160 » Fri Apr 13, 2018 4:17 am

Perhaps I am not smart enough but without a heating/A/C system how is insulation going to warm or cool the space?

I understand it can slow the temperature swings but won't it always return to ambient temp?

On warmer day won't it also hold the moisture in?

Uniballer
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Re: Should I insulate my garage?

Post by Uniballer » Fri Apr 13, 2018 7:51 am

An attached garage will gain heat from the house (even through the insulation).

Although I open my insulated-but-unheated attached garage to get the car in/out, it remains above freezing all winter, even when it is below zero degrees F outside.

jminv
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Re: Should I insulate my garage?

Post by jminv » Fri Apr 13, 2018 8:04 am

It's a nice feature. It makes it a more pleasant space to enter and is not too expensive.

You could also make use of the temperature difference, particularly in the summer, and install a hybrid hot water heater. This will cut down your utility bills while cooling the garage somewhat in the summer. They work saving your money down to about 40 degrees below which they operate in plain electric mode.

Glockenspiel
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Re: Should I insulate my garage?

Post by Glockenspiel » Fri Apr 13, 2018 8:06 am

bigdav160 wrote:
Fri Apr 13, 2018 4:17 am
Perhaps I am not smart enough but without a heating/A/C system how is insulation going to warm or cool the space?

I understand it can slow the temperature swings but won't it always return to ambient temp?

On warmer day won't it also hold the moisture in?
Thermodynamics. An insulated garage will retain heat that comes through the walls that are in contact with the house. In the summer, the garage gets cool air from the house and typically stays a little bit cooler than the outside temperature.

My garage is only insulated on the sides touching the house, and is tucked underneath part of the 2nd story of my house and the only time my garage gets under 32 degrees is when it's like 5-10 degrees below zero, or colder, outside. I wish I would have had the foresight to insulate it, but now it seems like too much work (not as high on the priority list) to take down the drywall and insulate.

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lthenderson
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Re: Should I insulate my garage?

Post by lthenderson » Fri Apr 13, 2018 8:09 am

Personally I would insulate the garage and I have done so twice before. Insulation is one of the cheapest things to add to a house, especially if the stud bays are already open and one of the easiest DIY projects. Afterwards, I think the benefits are worth it especially in a climate with weather extremes like the PNW. During the summer, it is much slower to heat up in the garage with insulation than without giving you much more time to work out there comfortably without being sweated out. I usually spend my mornings out in the garage during summer before it gets too warm to work. In the winter, it stays warmer with the doors closed thanks to the heated house wall which allows the snow and ice to melt from your vehicles every night. During the winter, any time I spent out there is usually in late afternoons after the sun has had a chance to warm it up a bit from the morning lows.

It might also be a selling feature to the next owner who would like a conditioned garage and to get one at that point one simply has to add a vent from your heating and A/C system already in your garage. It is a lot more work to insulate after the drywall is up than before.

ddurrett896
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Re: Should I insulate my garage?

Post by ddurrett896 » Fri Apr 13, 2018 8:18 am

RandomPointer wrote:
Fri Apr 13, 2018 1:42 am
I would like to know if it is worth it to insulate my garage or not, or just put the drywall and be done with it. I am concern that putting insulation to the garage wall and ceiling will just waste my money.
I would and when it comes time for a garage door replacement, get an insulated one. In terms of money, if you plan on doing it yourself get a quote from a company. I've heard from a few friends that the quote for installed insulation was cheaper or close to what it would cost to DIY.

whomever
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Re: Should I insulate my garage?

Post by whomever » Fri Apr 13, 2018 10:14 am

An attached garage will gain heat from the house (even through the insulation).
In addition, a slab on grade garage will gain or lose heat to the ground through the slab (gain heat when the ground is warmer in winter, lose heat when the ground is cooler in summer.

As others have said, insulation is dirt cheap to add before drywalling, and pretty hard to add afterwards :-(.

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RandomPointer
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Re: Should I insulate my garage?

Post by RandomPointer » Fri Apr 13, 2018 10:55 am

Overwhelming 'yes'. I will do it then.

@Just frank, I like the idea of having a blower to vent some air outside. Did you vent through the wall, or to the attic, or through the attic?

I am also concern that garage insulation will act as a double edge sword. I can imagine in the middle of hot summer I park my car with a hot engine, the heat will be trapped, and there is no ventilation there.

Spendy
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Re: Should I insulate my garage?

Post by Spendy » Fri Apr 13, 2018 11:04 am

You may want to look into closed cell spray foam for an airtight insulation option. The garage lets in exhaust fumes to interior airspace. Another option is flash and batt the walls and ceiling . The flash is thin layer of closed cell foam , as closed cell foam is more expensive.

nickjoy
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Re: Should I insulate my garage?

Post by nickjoy » Fri Apr 13, 2018 2:58 pm

Yes, it is worth it. Especially if you do it yourself.

I worked for a garage door company that my father started in the mid 80's. Insulating just your garage door will keep that room a lot cooler in the summer and warmer in the winter.

Since it's an unfinished garage, you can do it yourself pretty easily by getting rolls of insulation from lowe's or HD.

For the door, I would recommend not adding foam panels to it. The springs on the door are calibrated for a specific weight and the foam adds a lot more weight to it than you think. They have different springs for each additional ten pounds of weight. It's possible to get away with it, but usually the slack is picked up by the motor which makes the gearset wear out faster. You could add a little bit of tension to the springs, but be careful with the torsion springs (springs above the center of the door and attached to the wall), you need a special hardened bar to increase the tension for those.

If you garage door faces the sun in the morning or evening, it will be well worth it to insulate it. Also, insulated doors are usually much quieter so you can sneak out of the house without your wife knowing a lot easier.

wootwoot
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Re: Should I insulate my garage?

Post by wootwoot » Fri Apr 13, 2018 3:54 pm

What options are available for someone with an uninsulated garage that has drywall in place?

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just frank
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Re: Should I insulate my garage?

Post by just frank » Fri Apr 13, 2018 6:20 pm

RandomPointer wrote:
Fri Apr 13, 2018 10:55 am
Overwhelming 'yes'. I will do it then.

@Just frank, I like the idea of having a blower to vent some air outside. Did you vent through the wall, or to the attic, or through the attic?

I am also concern that garage insulation will act as a double edge sword. I can imagine in the middle of hot summer I park my car with a hot engine, the heat will be trapped, and there is no ventilation there.
In my tuck under, there is no attic....my living room is above the garage.

I went out the wall where it was convenient.

As for the heat, the heat of the engine is much smaller than the thermal loading from outside. Mine sees no sunlight, and so never gets hot at all. If excess heat in the summer is a concern, insulate the attic first and well.

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