Add insulation to old house attic?

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Old 08-11-16, 08:19 AM
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Add insulation to old house attic?

I was told many years ago one of the floors with purchasing in old home is that it is very difficult to make it energy efficient, because you can't just do one thing, you have to do many things. My house was built in 1979 and I reside in Houston, TX. Ive been going down the long road of making changes to increase the homes energy efficiency over the past few years.

Recently I've had my eyes on the attic. I read recently that a home should have at least 10-16 inches of insulation in your attic. Currently there is about six inches. I've wondered if it was worth it to blow in 6-10 inches on top of what's there and add a radiant barrier. I was told by someone I shouldn't do this unless I wanted to replace all the insulation in the walls too. How true is this? Or would putting this much work into the attic be worth it?
 
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Old 08-11-16, 08:37 AM
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You sound like a good candidate for an energy audit by an independent firm. They will test your home and advise you as to which improvements will give you the best return on investment and which will give you the best improvement in comfort (not necessarily the same). As you have learned, there are so many potential improvements you can make that it really helps to have actual data to guide your choices. An audit will also take into account the climate of your area; something that is difficult to factor into the general advice one gets online....
 
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Old 08-11-16, 08:58 AM
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I also believe an energy audit is something you should consider. When you ask about "worth it", that's something dependent on many factors including the type of energy you use and how much of it, the style of home, and number of floors as well as the current insulation levels. An energy audit is an efficient way to figure all that out.

Second, approx. 90% of homes in the US have inadequate attic insulation so it's almost certain you're in that category, particularly with the level of insulation you describe. Thus, adding attic insulation will probably be recommended.

Finally, I guess age is relative. I was expecting something earlier than 1979 when you said old house.
 
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Old 08-11-16, 09:43 AM
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Hi Thomas, I'm an energy auditor so definitely agree that the information an audit would provide would be very helpful. However, this IS a DIY forum and you can gather and process much of that information yourself, especially with the help of several auditors right here.

Some questions.

What is in the attic? TX has a bad habit of locating the ac unit and/or much of the ducts up there and if so that affects the advice we provide.

There are guidelines for attic ventilation and they should be reviewed. But that is part of the decisions related to the above.

What style is the house?
Basement, yes or no?
And what have you done so far.

That will get us started.

Bud
 
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Old 08-11-16, 10:51 AM
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Thanks for everyone's replies, I want to say at one point in time I may have heard of an energy audit, but I never knew what it was. Now that I know that's probably what I'll end up having to do. But I'll answer some of y'all's questions the best I can.

Single story four bedroom house. 1800 square feet, 1200 livable as the garage is factored into that. No basement (rare in Texas), A/C and ducts are in the attic.

What I've done so far:
- replaced all windows with double pane ergot gas windows, and all windows have solar curtains
- insulated the concrete
- replaced & remaped all ductwork
- replaced A/C unit (25 years old) with modern
- installed ridge vent for attic
- The parts of the house that are not brick, I remove the siding, put up tar paper, and Hardy plank (didn't have any wrapping before)
- replaced all weatherstripping on exterior doors (or doors to garage) with modern stripping (old ones were metal)
- replaced all exterior doors (wood) with steel doors.
- replaced shingles with solar reflective shingles.

And although this is not technically a home-improvement, I did replace every single light bald in our house with an LED bulb to reduce energy consumption and the heat produced by incandescent light
 
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Old 08-11-16, 12:59 PM
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One of the basic functions of an energy audit would be a blower door test where they depressurize the house and measure how much leakage there is. During that test some energy audits (recommended) will do an Infrared inspection to pinpoint those major leaks. Air sealing is a high priority.

With your ac system in the attic the typical advice is to seal the attic and insulate the bottom of the roof, often spray foam. This creates a semi-conditioned attic space to eliminate the energy loss directly from the air exchanger and all of those ducts. If you opt to not go this route then have the energy auditor test the duct system and identify all leaks. Then seal and add more insulation.

Sealing the attic is called an unvented attic and eliminates the need to insulate the attic floor or air seal it.

Bud
 
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