re: Adding Attic Insulation

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1. Is the research I've done correct that max depth for attic insulation in S. Louisiana is 16“?

1a. Should I put the full max height?

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The recommended R Value is between R-30 and R-38. Using loose fill cellulose insulation, that's around 10 inches.

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2. Will it be much cheaper to do myself? How much (guesstimate)?

2a. If not, what would a company charge?

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Yes. Depends on a lot of factors but blow and go +$400. Doing the job right +$1200.

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3. Is there a formula for how many (bales?) of insulation I'll need?

3a. What R value should I buy?

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R-value = 38 – Existing R-value = Needed R-value

Measure the existing insulation. A conservative estimation is R-3/inch. Each package of blow in insulation has an estimated value of R-3.7/inch and a coverage area of 40 sq. ft.

Let's say your average insulation was 7 inches.

R-value needed = 38 – 21 = 17

Lowes and HD carry R-19 cellulose

Let's say 2,000 sq ft/40 = 50 packages should be more than enough to get you covered.

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4. Any suggestions, tips or guidance?

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Doing the job right requires more than blowing insulation in thin spots. I understand not wanting to pay $1,500 - $2,000 for professionals to do it. If you DIY it though, take the time to do the extra things like raking the existing insulation back and air sealing the envelope for thermal bypass leaks.

This means sealing recessed lighting, wiring or pipe holes, electrical boxes, and gaps around the top plates and gypsum board. Insulation doesn't prevent leaks into your attic. It just slows them down.


Check your duct work for leaks while you're up there. While I was up in my attic I found a penetration in the damn supply plenum, flapping around as if it were a vent.

Make sure you have your soffit vents protected so you're not blowing insulation into them and blocking air flow.

Lastly, PPE. You're going to be spending some decent time in your attic no matter the scope of the job you plan on doing. There's a lot more nasty stuff blowing around up there than just insulation so dress accordingly.