# What's the best way to install a radiant barrier insulation?



## Windows on Wash (Aug 30, 2011)

Where is the building and what is the construction (I.e. Framing, trusses, rafters, etc.).

Pictures are your friend here. 

Radiant barriers are really application specific and do have application but they are far from the magic bullet they are touted as.


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## spauld (Oct 15, 2014)

Thanks for the reply. I've attached a pic of the interior of my building. It is located in Arvada Colorado, in my back yard. You can see by the pic they used 2x4 framing for everything (walls and roof). My hope was to leave the collar ties you see exposed, and just go for 3.5" of standard insulation in every exposed wall/roof cavity, then face each cavity with some kind of radiant barrier before applying the drywall (Prodex?) I know this is not much insulation for a ceiling application, and I got a few bids on spray foam (SPF)...but after reading some horror stories about what happens with SPF if not applied properly, I've backed off that approach, particularly since I've heard that some of the issues with SPF happen slowly, over time (biggest issue seems to be shrinkage and pulling away from the studs and sheeting). ...and once drywall is installed, how would one know if the SPF has failed? Any comments would be welcomed!


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## 47_47 (Sep 11, 2007)

That's a good sized shed. Are you going to condition (heat and or ac) this shed? Do plan on having any venting installed? It will get hot in there without air flow.


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## spauld (Oct 15, 2014)

Yep, was planning to cool it in the summer and heat it (to some degree) in the winter. The building does not need to be kept at "room temp" during the winter, warmer than freezing (maybe like 55F to keep the water pipes from freezing), then I'll fire up my wood stove a couple of hours prior to being out there for the day/evening. I also am running gas to this building and will have a 30,000BTU ventless blue flame or infrared catalytic heater.

No, I have not considered adding vents. I know that the proper insulation approach for this building (given that it will be heated) would be to install soffit vents, a ridge vent and some kind of insulation spacer between the roof trusses to allow for air flow between the roof and insulation, but hindsight is always 20/20. My hope now is that I don't get too much moisture buildup in that area. The fact that I live in a fairly dry climate may help some.


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## Windows on Wash (Aug 30, 2011)

+1

You need to vent that roof. 

Easiest and most effective way to do it would be to attached a foil faced rigid foam to the underside of the chords of the trusses. Have the foil face the underside of the roof deck. Vent the roof. Seal all the seams and cover with a fire rated drywall.


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## Perry525 (Jan 10, 2010)

Do you hope to redirect the heat from the sun away from the building, or to try to keep the heat in? If repelling the solar heat, then the best way to deal with this is, to paint the outside silver or white. Internally, there will be very little heat radiation from your proposed system.... so both ideas are really none productive.


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## 47_47 (Sep 11, 2007)

Where would you put the intake vents? How much of an overhang do you have on the gambrel roof? Can you post a picture of the outside?


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## spauld (Oct 15, 2014)

There is a place to vent the roof since there is an overhang, but wouldn't I need to put a vent in for every one of those roof/ceiling cavities? Would I have major issues if I didn't vent this structure? Windows on Wash; would I attach the drywall directly through the foam board with long drywall screws?


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## Windows on Wash (Aug 30, 2011)

Yes, that is how you would do it. 

You would need to vent every joist/truss cavity for balance.


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## spauld (Oct 15, 2014)

OK, well I want to do this right the first time....since it will be dry-walled. Once that's done and the place is painted/finished, I sure don't want any issues with moisture, etc. So I'll get this venting in place before I install my insulation. All; Thanks for the feedback. To answer your question Perry 525, I guess I want to keep heat in (winter) and cooling in (summer...will be installing a swamp cooler).


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## 47_47 (Sep 11, 2007)

Just watch where you run your water lines. They must be run on the conditioned side of you insulation. Good luck on your project.


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