What is the correct depth for attic insulation?
Many people ask “How much attic insulation is enough? How much R-value should I have?” The picture above gives you a decent representation of what you should have if you are using insulation batts or blown-in fiberglass, or cellulose.
Around Austin, most homes are under-insulated according to the current IECC and City of Austin building codes. If you can see the joists in your attic floor, then your home is under-insulated. You want to have at least an R-38, but more is better.
What about attic spray foam insulation in my home?
Since spray foam is applied to the roof-decking and rafters on the attic ceiling, the R-value required is only R-25 or about 7-inches of open cell foam. Why? For starters, spray foam is a significantly better performing product, and it is a barrier for all 3-types of heat transfer. Plus, with spray foam, you don’t need an extra radiant barrier because spray foam takes care of radiant heat for you.
Which attic insulation material is best for the Austin Texas area?
This is a very common question. The fact is that it depends on how you plan to use the building. If you are a production builder and just want to meet code requirements while building the cheapest product, then I have one answer. However, if you are the one who is going to own the building for at least 3-years and pay the bills, then there is a significantly different and better option. Check out my Insulation Materials Comparison Infographic here.
Where to install attic insulation?
The entire attic floor should be covered with insulation. If you are using spray foam, then the attic ceiling (roof deck) should be sprayed.
When to add attic insulation?
Are you having your Air Conditioner replaced? This is a great time to consider re-doing insulation on an existing structure? Why? Two-words. Sealed-Envelope. What does that mean? Sealing your building’s envelope is the smartest energy saving thing you can do for your home. It involves making your attic temperature 3-5 degrees higher than your living area, instead of it being 150-degrees in the summer.
Why does the timing matter? If you want to seal your envelope, you have to install a 90% or greater efficiency HVAC unit in the attic. Otherwise you risk your building blowing up from combustable air problems. However, if you are not ready to do a sealed spray foam insulation envelope, you can make your building capable of having a sealed envelope. Simply, have a 90% or greater efficiency unit installed, and tell your HVAC company that you plan to have a sealed envelope in time. Then you will be all set.
When else should you add attic insulation? Don’t wait until you are about to sell the building. Do it when you first buy the building, or NOW. Why? Look, Austin requires you have your home Audited before selling if it is 10-years old or older. This Audit will uncover the lack of insulation, which the buyer may then use as a reason to lower their offer, or require you to install it as part of the deal. What does it mean? You will probably pay for insulation when you go to sell, so why not get it installed now? Then you can enjoy the comfort, save money on bills, and invest that savings into whatever your heart desires.
When to remove or replace attic insulation?
It is more costly to remove insulation than it is to simply add more on top of the existing insulation. Here are a few reasons why you would want existing insulation removed:
- Is someone living in the building allergic to the insulation material installed?
- Does someone in the building have a sensitivity to outside allergens coming into the home via the vented envelope?
- Is there excessive dust, dust mites, and other things filtering into the home via the attic?
- Have animals nested and left feces behind that is venting into your air space?
- Do you have mold or too much moisture in your attic?
- Do you have asbestos in your old attic insulation?
When you remove the insulation, you can hire the installer to air-seal the attic floor if you are replacing the insulation with another blown or batt material. If you are creating a closed envelope with spray foam, you can then remove nasty old insulation and create storage space across your attic floor.
Calculator: how much attic insulation do you need?
Your best bet is to have a professional give you an estimate. Most of the time with insulation, it is more expensive to install it yourself than it is to hire a pro. Very counterintuitive.
With that said, I have written an in depth explanation of materials calculation for fiberglass here and spray foam insulation here. Please note that it is deeper into the article. Look for the headline “how much insulation do I need” to find the calculations.
What does attic insulation cost in Austin TX?
The cost ranges widely depending on whether you have fiberglass, cellulose or spray foam installed. However, you are often looking at $1,500 to $2,500 for the whole job.
Here is what to do next
Check out my full Insulation Buyer’s Guide and Bonuses where you will learn everything you need to know to make an intelligent and informed decision when it comes to properly insulating your attic.