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Old 01-29-2009, 07:57 PM   #1
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Can I have to much insulation?


I'm redoing

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Old 01-29-2009, 10:46 PM   #2
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Can I have to much insulation?


dont know if you can have too much insulation but thers probably a point where it becomes not cost efficient .but you can have so much insulation that you block ventilation,which is not good

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Old 01-30-2009, 01:08 PM   #3
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Can I have to much insulation?


This is actually a good question because I'm currently working on removing an old leaky sliding glass door with just a simple wall. I'm framing it up myself, drywalling, and adding outdoor wallboard for the time being (gonna' be completely re-doing the exterior in a couple of years). I've priced standard R-13 insulation that's 4" thick for the walls but I've also seen R-19 insulation meant for 6" studs. I'd definitely like more insulation as this is a west-facing wall that gets beat on by the sun in the summer but if I pack 6" insulation into a 4" space, is that a bad idea (or just wasteful with no gain in insulation value)? Also, I'm seriously considering spray-on expanding foam insulation since it would be nearly air-tight and then I wouldn't need to worry about missing small gaps in the wall...
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Old 01-30-2009, 01:39 PM   #4
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Can I have to much insulation?


You reach a point where the cost of the extra insulation is greater than the energy savings that it produces, s o it never pays you back. That number varies by your location (degree days of heating or cooling)and energy costs. Packing 6" of insulation into a 4" space will not give you a greater R value. Fiberglass insulation should be installed in the density and thickness meant for the space. Packing it in is likely to be counter productive since it will become closer to a thermal conductor than an insulator.
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Old 01-30-2009, 02:03 PM   #5
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Can I have to much insulation?


Ahh, that actually makes a lot of sense!! Thanks a ton. Yeah, I think I'm going to look into spray insulation kits at the local big-box store and give it a try. Since it's a relatively small area (just 8' x 20') it will be a good place to practice!!
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Old 01-30-2009, 03:45 PM   #6
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Can I have to much insulation?


There is a diminished return once you get to a certain insulation thickness. For 2x4 walls I use R15 - its made for a 2x4 wall. It's 15% more insulation in the same space

Compacting R19 into a 2x4 wall results in only R13 - so its a waste of $$. I build 2x6 external walls for my additions & use R19.
Cathedral ceilings with 2x12 I use R38C, attics most people seem to recommend R49

What are you redoing?
Walls, floors, ceilings ??
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Old 01-30-2009, 04:27 PM   #7
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Can I have to much insulation?




Mind you, this is just a temporary fix that should only last about 2 years as I'm planning on remodeling the entire house at that time. Right now, I'm removing a VERY leaky sliding glass door and framing it in. Then I'm removing all of the exterior wall board on the outside wall to the master bedroom and re-insulating that entire wall since there has been a lot of deterioration. Also, the setting sun in the summer just BAKES that room since it's mostly glass and a very thin and poorly insulated 4" wall keeping it out. My current thought is to use the foil-backed OSB on the outside and then cover it with exterior wall board. I also want to add another 2" of wood to each stud and go ahead and use 6" insulation in the wall (either fiberglass or expanding spray-foam).

Personally, I tend to "over-engineer" just about everything I do so this thread helps a lot since there's just NO advantage to stuffing 6" fiberglass insulation to a 4" stud wall (and not only costs more but may reduce the R-value). Thanks for all your help guys!!
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Old 01-30-2009, 05:14 PM   #8
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Can I have to much insulation?


foil backed radiant barriers need a air space to work
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Old 01-30-2009, 05:34 PM   #9
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Can I have to much insulation?


Quote:
Originally Posted by strublesiding@optonline.n View Post
foil backed radiant barriers need a air space to work
Thats an interesting comment and its got me thinking! My house was built in 1948. Rather than wood lathe, they used foil backed plaster board. And no insulation in the stud cavity!
As the walls were hollow, I contracted to have cellulose blown in. Yielding about R15, the contractor said!
So, my question is, did I negate the radiant barrier?
Just an idle question, even though my heating costs are very reasonable! In fact, d*mn good!
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Old 01-30-2009, 05:39 PM   #10
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Can I have to much insulation?


Quote:
Originally Posted by strublesiding@optonline.n View Post
foil backed radiant barriers need a air space to work
Can you explain why?
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Old 01-30-2009, 05:54 PM   #11
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Can I have to much insulation?


Quote:
Originally Posted by perpetualjon View Post


Mind you, this is just a temporary fix that should only last about 2 years as I'm planning on remodeling the entire house at that time. Right now, I'm removing a VERY leaky sliding glass door and framing it in. Then I'm removing all of the exterior wall board on the outside wall to the master bedroom and re-insulating that entire wall since there has been a lot of deterioration. Also, the setting sun in the summer just BAKES that room since it's mostly glass and a very thin and poorly insulated 4" wall keeping it out. My current thought is to use the foil-backed OSB on the outside and then cover it with exterior wall board. I also want to add another 2" of wood to each stud and go ahead and use 6" insulation in the wall (either fiberglass or expanding spray-foam).

Personally, I tend to "over-engineer" just about everything I do so this thread helps a lot since there's just NO advantage to stuffing 6" fiberglass insulation to a 4" stud wall (and not only costs more but may reduce the R-value). Thanks for all your help guys!!
Are you taking out the only door for easy access to the Courtyard? I might take out the slider & put in a 1/2 glass door & a window. At the very least I'd put in a window for cross ventilation
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Old 01-30-2009, 06:00 PM   #12
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Can I have to much insulation?


Quote:
Originally Posted by Scuba_Dave View Post
Are you taking out the only door for easy access to the Courtyard? I might take out the slider & put in a 1/2 glass door & a window. At the very least I'd put in a window for cross ventilation
In the 10 years we've lived here, we've only used the access to the courtyard from the master bedroom to ease installation of our California King bed and my arcade game. Other than that, we never use that door. Also, my remodel involves claiming the courtyard for a room addition so this wall will become an interior wall at that time. I also plan on installing plenty of decent windows and a door to the outside with the remodel in the near future but we've lived without windows and access to the back for many years now and just want to live the next 2 years in a significant level of comfort from the elements now!!

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