My girlfriends home....abt 1800 sq feet in north Missouri...... has 6- 8 inch fiberglass batting between the rafters in the attic.
She was considering buying some more cellulose insulation and blowing it in her self. Cost would be abt oh say $400 tops I think.
BUT some questions!
Would adding insulation above 6-8 inches REALLY be cost effective given the location and decent condition of insulation already there?
We were both kind of surprised when looking around in the attic to find that batting. We expected loose insulation that had settled but this is not the case.
Can you MIX two kinds of insulation like that.... i.e. adding cellulose on TOP of fiberglass batting?
It is not all that easy to say for certain, but I would believe it would be a good investment. Remember it will also make summer cooler or if A/C then it will be cheaper as well. I suspect that in the long run it would save on heating alone.
Personally, I'd add more batts. If you ever have to do work up there, it will make everything far easier and cleaner. Just lift the batts out of the way, run your wires or whatever, and put it back. It is an easy job to DIY.
When my home was built 40 years ago, they installed R6 in the attic which, presumably, met code at that time. Today, it stands at R60 and that's the minimum I would consider adequate in our climate (7,800 HDD). If you're going to go through the effort and expense of upgrading your insulation, you might as well kick it up a notch or two higher given the direction energy prices are heading.
With respect to adding cellulose on top of fiberglass batting, I don't think it's a good idea -- the extra weight would end up compressing what you have in place now, reducing its effectiveness considerably. I would be inclined to add R20 or, better yet, R40 fiberglass batts perpendicular to the ceiling rafters.
Depends on when she sells the house and moves. The breakoff point may be 3-10 years. I live in Tennessee and have 3 feet of insulation in the attic--helps the A/C. Don't forget about those Styrofoam or cardboard "chimneys" that are attached tot he roof to provide the proper ventilation and to help prevent ice dams.
Sure. Or you can add additional batts (without paper) on top of the existing ones.
A few infrared pictures of the house will tell you where the heat loss is happening. Caulking and/or replacing windows may be effective.
No, I would leave the existing batts in place and install the new batts on top, but run them perpendicular to the ceiling joists. This accomplishes two things: 1) it minimizes the weight placed on the existing batts, thereby minimizing their compression and subsequent loss of R-value and 2) it reduces the thermal bridging through the ceiling joists.
If the old batts come to the top or near the top of the boards, then place new batts at right angles to the old ones. This will cover up all the wood. In other words, if looking at the batts they go from left to right, place the new batts frount to back as you face them. Be sure if there are vents at the edge of the wall you do not cover them up. This is to ventilate the space in the summer and help with the cooling.
Putting additional insulation is a good idea, particularly up there where the heat rises and leaks out. Also, where the heat comes in from the hot roof.
That being said, there are several other things that can be done cheaply that will help, sometimes SUBSTANTIALLY.
Check ductwork and if needed use NEW GOOD foil type tape rather than cheap duct tape. It is surprising how much leakage there is from tape deteriorating or not being put on properly, if at all. Just plain taping around all ducts and connectors is a good idea.
Check ALL connections, and if necessary, caulk and add screws.
Before you just blow in the ceiling, get around up there and see if there are any places where insulation is plain missing, not put in right, not fitting right, etc.
When blowing in new, be sure to get out to the edges, where it's hard to get. Use a broom handle if you have to to push it out there.
Install those little foam sheets in all the receptacles and switches. They're cheap and effective.
Check windows and all openings. Many times, there's large air losses around vents and anywhere something perforates the perimeter of the capsule.
I'll bet by the time you are finished, if you do a thorough job, you will be surprised by how many leaks and shoddy installation mistakes you can find. Use cheap weatherstripping where you have big gaps.
Lastly, do a pressure test, which can be as simple as mounting a fan in a piece of plywood in a window. Make the air flow in to get the pressure inside positive. Then get a piece of cotton rope and light it so it smokes. The smoke will follow any drafts. Check with your local power people and power conservation groups to see if they will bring their high dollar infrared stuff out and give you a free or cheap analysis.
Yes, insulating more is good. But there's a lot of free and cheap things that will get you even more tightness and lessen power bills.
I agree. Run the bats 90 degrees off the current bats and you'll close off a lot of the leakage.
I blew some cellulose into an attic recently that had blown fiberglass with some thin spots. It covers nice but is really messy if you ever need to get up there for anything.
If you're having this much trouble grasping the rather simple concept of ADDING insulation to your attic, you should hire a professional.
Go to Home Depot and look at an package of R38 insulation. Installation instructions are right there. The Pink Panther will show you how to install new insulation ON TOP of the old insulation, perpendicular to (90 degrees to, "criss-crossed", across the rafters, whatever) the existing insulation.
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