insulation + metal garage... what you think

[knightp25]

I have a metal garage, 17x24

I insulted the roof of the metal building with R13, I just completed the whole thing (picture below when I started)

In the summer the metal building is like a sauna inside, so I am hoping the insulation will help. (I have not done the walls yet)

My thought was to also put radiant barrier foil overtop of the insulation, to hide the look of the insulation and to help prevent dust and what not.

I also eventually plan on doing the walls with insulation and OSB.

Am I on the right track for keeping the heat out? Any thought or suggestions thanks

 

[Nexussian]

My father's metal building he just had built in AZ is insulated.

He insisted on it in the original plan.

Insulation came as a kit and is contained within a plastic envelop (bag) that acts as both a vapor barrier and an air barrier.

I don't know where you are located, putting at least the state you are located into your profile so we can see that helps us give you accurate suggestions.

In AZ he chose to put R30 in the ceiling, and I believe R19 in the walls.

Last spring, after all the doors were in and sealed it got to 101° F in the shade, ambient, outdoors.

At approximately 2:00 in the afternoon he checked the thermometer he had put in the shop previously and the interior was only 81°.

I know some people will tell you that for the cost of the insulation that a roughly 20° reduction isn't worth it, but think of future costs, ie if you choose to air condition the space, you are only having to pull the temperature down 8° - 10° instead of 30°.

While the building is a light color, with a "solar white" roof (highest reflectivity of any color we could find) the biggest difference we found, when researching (to include visiting people with similar buildings in the area) was the shops that were tolerable in the summer had two things in common.

1) Insulation, that concrete pad has several tons of thermal mass, might as well use that to your advantage.

2) Air tight, sealed just like you would want your house, any air transfer from interior to exterior reduces the effectiveness of your insulation (just like it would in your house).

If your building is in "galvanize grey" or anything darker, you might see what painting it would cost, not only could it reflect some heat, it can help seal any small air leaks (edges of the sheeting, not likely to seal vacant screw holes ).

Good luck, I've been in some of those "work saunas," not fun.

 

[egnorant]

As the owner of a Texas car oven myself I have given this a lot of thought. Discovered my thermometer tops out at 130 degrees!

My goals were to keep the heat out, keep the heat IN, stabilize temps to prevent condensation and seal it up more for critters and dust.

Insulation is very helpful and works but I went a slightly different route.

First was to keep the heat out! A roof covering a 32 foot trailer on the South side helped a lot on my 28 foot deep shop. East side has trees which leaves the roof and west side. I even thought of covering parts with my license plate collection just to keep the sun from hitting the building.

Insulating the garage doors (West side) had a noticeable effect.

I am also looking at radiant white paint for the roof and other areas with a lot of Sun exposure.

So I see insulation as the 3rd layer of keeping out heat. First, don't let the sun hit the building! Second, reflect away as much as practical and the third layer is to prevent the heat from entering the interior (insulation).

You talk of a radiant barrier as almost an afterthought. It helps more than you may think!

Bruce

 

[Nexussian]

Edit.....
I am also looking at radiant white paint for the roof and other areas with a lot of Sun exposure.

.....Edit

What paints have you looked into?

The "Solar White" on Pop's garage cut absorption by half of what other shades of white advertised (really bright).

I would also be curious to know how hard it is to apply as he has a small garden type shed that is a real hotbox.

 

[knightp25]

Thanks, I am located in PA, I just finished the insulation, i did notice yesterday, that the building did not get as hot inside as it usually does, since completing the roof.

I was going to put radiant barrier on top of the insulation as a second layer of covering.

Also plan on insulating the walls with R13 and OSB.

I dont get any moisture in the building yet that i have noticed. I do have a Brown colored roof which i know doesnt help either