Thermal Barrier?

[ludakris04]

I have a new construction home with an attached garage. I just ventured up in the attic space above to check it out. There is a room over part of the garage, it is totally insulated and sealed from the rest of the "attic" space over the rest of the garage. I was told there was "some" insulation above the garage and believed it to be true since my winter temps have been very moderate inside the garage. Well, I found out there is no insulation up there. My concern moves to the summer months. My house faces south with a large portion of front facing roof being above the garage. I want to insulate some, but not sure the best route to start.. I am thinking a radiant barrier stapled to the underside of the roof... Does this stuff work?

 

[Haywood]

I see a ridge vent in the picture and since its new I'm going to assume the soffit has vents.. Why not just roll out some insulation between the trusses? It'll be easier to install, and you'll probably get a higher R-Value for your money.

 

[coolbreeze1340]

I agree with Haywood. The radiant barrier is great when used WITH reg. insulation already in place but as a stand alone it is not enough for most climates.

 

[ludakris04]

my concern was with heat build up.. I figured the barrier would reflect alot of the suns heat after it beats on the roof all day.. I don't want the garage to feel like an oven this summer.

 

[Erampu]

Do NOT put insulation on the underside of the roof unless it's a living space. There needs to be air flow under those shingles. Just insulate between the joists.

 

[kbs2244]

I would just wait and see if do have a problem.
You may be trying to fix a problem you don't have.

 

[emanonii]

I agree with kbs2244 - wait until it gets a little warmer/sunnier and see if you really will have an issue.

That being said, yes, radiant barriers really do work. I used to have a ranch home, and all of the a/c ducts were in the attic. During really sunny days in the summer, the attic would get super hot (yes, I had a ridge vent) and the air coming out of the vents would barely be cool. I put the radiant barrier foil up (specifically the ultima product from radiantguard.com), and it made a HUGE difference. It didn't keep the attic cool, but it did help a lot. When I was in the attic stapling it to the rafters, I could feel the difference in the part of the attic that I finished, and the part I hadn't done yet.

By the way, I am outside of Philly - similar climate/weather conditions to Md.

 

[cbracer]

I put the radiant barrier foil up (specifically the ultima product from radiantguard.com), and it made a HUGE difference. It didn't keep the attic cool, but it did help a lot. When I was in the attic stapling it to the rafters, I could feel the difference in the part of the attic that I finished, and the part I hadn't done yet.

You stapled them to the rafters of the roof? Or around your vents? Or on the floor of the ceiling? Couldn't figure out where exactly you put them?

 

[Torque1st]

Radiant barriers work for a short time only. They accumulate dust which destroys their effectiveness.

 

[bigdav160]

Radiant barriers work for a short time only. They accumulate dust which destroys their effectiveness.

Dust would not be problem with the barrier stapled to the underside of the rafters.

 

[Torque1st]

Dust would not be problem with the barrier stapled to the underside of the rafters.

Unfortunately you are incorrect. The dust infiltrates very rapidly in that application.

 

[emanonii]

You stapled them to the rafters of the roof? Or around your vents? Or on the floor of the ceiling? Couldn't figure out where exactly you put them?

To the bottom of the roof rafters.

 

[matttys]

Install forced ventilation in the form of an exhaust fan. Won't matter how hot the roof is then and it will be thermostatically controlled.

 

[Falcon67]

It works and according to the studies has a faster payback than insulation. Tack it under the rafters, or cut it in strips and tack it under the decking.

 

[monksblood]

Give it a summer to see what happens. Personally I find that an exhaust fan works best

 

[Garage Dog]

Your question is does this stuff (radiant barrier) work? The answer is yes, but the real question is how well and how cost effective is it...

What should you do? As others point out maybe nothing; how long will you live there, how will you use the garage, is the cost associated with insulating a factor, what is you return on investment (even if that return is only comfort)?

If it was my decision - I would spend my money on two things listed above that I know are effective.

1. Insulate you garage ceiling (between the bottom cords of your trusses). Either blown in or rolled in works fine and is cost effective. This gives you your barrier between you hot attic and your usable garage space.

2. Make sure your attic is properly ventilated (combination of soffit vents and roof vents), most attics are hot when the sun beats on them and the soffit and roof vents are designed to help minimize that heat build-up - heat is circulated up and out through the roof vents. Look at what you have for ventilation, do a little research.

As mentioned above forced ventilation is an option, just make sure your have an inlet vent cfm capacity (soffit vents) to supply the cfm's the new fan will draw.

That is where I would start, and that is how millions and millions of homes are effectively insulated...

Good Luck