I'm finally getting around to insulating my attic. I finished installing the pull down stairs last week since original opening was next to impossible to use. The ceiling joist are 2x6. The original 1941 part of the house has 4 inches of cellulose insulation. There was 14x10 add on to the kitchen at some point at that contains 4 inches of fiberglass. I know I am way under insulated.
I have been browsing around online for the past few hours. I'm trying to figure out if I should leave the old insulation there and pile new on top or toss it and start fresh? The old insulation has roofing debris and evidence of past water leakage. I'm really thinking since there is so little just starting fresh would be the best.
The next question is what to replace or go over it with? I want to use the attic for some storage. My plan is to frame on addition hieght with 2x4's to give me 10inches avalible for insulating and then put plywood on top of that. I know I'm looking for R38 or better for my location. I know just about anything is better than what i have now.

 

It is really up to you. The extra insulation that it provides will help. I would dig around here and there and make sure there are no rodent homes, or areas that were saturated and are now decomposing. I would take it out personally. You can use Batt, or blown in. I prefer the batt myself, but most lumber yards that sell blown in, rent you the blower for free. It is a mess, but it gets into every nook and cranny. Blown in may actually end up cheaper, but it packs down over time. Batt insulation not so much.

Either way just make sure not to completely block off the soffits, you need to have air circulation.

 

If you don't mind the extra expense, closed cell spray foam is about R5 per inch and is also a vapor barrier. If you remove old stuff and have it sprayed joist depth then you would save adding lift to floor and have the best insulation.

 

In case you're not familiar this is done by a company not with cans.

 

Man, Digger, who gave you that nickname? Some butthole, I'm sure.

I'm no expert, but in my house (rental) the roll out pink fiberglass stuff is about 2 ft thick for half the attic, and the blown is about 6 inches thick on the rest, and you can feel an incredible difference just walking through the house in the summer.

Just my .02.

 

Do you have a mirror handy.
The foam i am talking about is sprayed in and expands to become solid. It is the best per inch you can get but not cheap.

 

Yeah, I know what you were talking about, forgive me if I was misleading.

I do not have experience with that, but I bet it is superior, hands down.

ha ha...

 

And to top it off, your hose will float once you install the expanding foam insulation. The drawbacks, other than cost is in you ever have to deal with it in any way, it's a pain. You cannot add wires inside a wall or cavity once its been done.

If it were me, I would leave the current insulation, maybe take a long stick and smooth it and redistribute it if needed anywhere. Removing it is going to be your worst nightmare of a mess. Get some rolls of bat insulation WITH NO VAPOR BARRIER PAPER on it, as highly R rated at you can afford, and roll it on top of what you have, 90 to all the ceiling joists. I emphasize with no paper, because that paper will trap moisture under it and make a mold problem that you do not want. It needs to breath. Rolling it 90 degrees to the joist will let you use thicker batts than what your joist are and will help keep it from smashing your cellulose any further. I have 2 layer of batts in my attic, run 90 to each other. The first is joist depth, 2X6, the second is a huge R30, making my insulation dern near knee deep.. I got the top layer free, fully sealed and never opened. it has no paper. I tossed it all up in there during the hot days, then took a 10 foot pole and spread it on the first cool evening we had. I'd toss a bundle in the general area, split it with a knife, then run, as it would grow like a giant pink hulk. Then just used the pole to put it where I wanted it. Make sure too that you don't block and roof soffit vent air paths. That's another big no-no. Those soffit vents need to breath. And never pack insulation. It' snot the fibers that hold heat/cool, it's the air trapped in the fibers that stop heat transfer. With it packed, theres not enough air trapped in the fibers for it to do its job.

Another thing to do that is well worth the small expense, is to go thru your attic with some expanding foam and fill all wire and pipe holes that are going into the tops of all the walls, and seal around all light and fan fixture boxes, and kitchen and bath vents. You'll be blown away (ha-ha) if you knew just how much air those little holes and cracks let into your house. And go wild with it. Seal everything. Then make sure all your ducts are sealed and all duct fitting are painted with a sealer made special for that. A gallon form Lowes/Home Depot will usually do a whole house. Then once the holes air are stopped and the vents are sealed, proceed to lay down all that new fresh insulation.

And once you've done all that, you might as well insulate those stairs: http://www.batticdoor.com/atticstairinsulator.html

Duct sealer example: http://www.ductmate.com/files/specsheet/EverSeal.pdf easy to paint on yourself. Throw the brush away when done.

 

Right about the wires etc, the foam encapsulates everything so changes later are hard. But considering the fuel costs today and in the future it may be worth it. JMO.