Remove and Replace Attic Insulation

[Accolay]

Hey everybody.
I'd like to use the attic for storage, but there is fiber fill (the newspaper kind) insulation on top of fiberglass between the joists, and lots of mouse and squirrel? poop on top of that (throughout the house, actually). The dusty fiber insulation is not really conducive to storing anything, or access for that matter.

What I'm thinking about is bagging up the old insulation and cleaning it out, then lay some plywood down for flooring. Then I would put furring strips on the rafters and putting the paper faced insulation batts, and then a vapor barrier, (and maybe one of those high tech radiant barriers on top of that), and add some attic stairs for access.

Whatcha think? Is there a better way? Should I instead fur out the floor just get new insulation batts on the floor and lay plywood on top of that? It gets really hot up there, and I'm not sure that'd be great for stored items.

[shazapple]

What size are the floor joists and what is the span? I would check to ensure they are big enough to hold weight. You're basically converting this into a living space, and there is a big difference between ceiling joists and floor joists.

There are companies that can remove the existing insulation using a vacuum. Way cleaner than doing it yourself. Regardless, I'd buy a good mask. Ensure there is no tar paper or other type of vapour barrier in the floor, it would have to be cut out.

How deep are your joists? How much do you plan on furring them out? You need to make space for ventilation of the roof as well (about 2"), and maybe even install soffit and ridge vents if you don't have them already. Paper facing is not needed if you are installing a poly vapour barrier over top. The radiant barriers typically go on the exterior side, and even then I'm not really convinced they are worth the trouble.

[s.kelly]

I would do alot of research before using a method like what you are proposing. I would be concerned that air leaks under the plywood could put the dew point inside that space giving you condensation.

Better might be to get spray foam in the joist bays and plywood over, or close the attic and makke a "hot" roof assy bringing the attic into the conditioned space. That would also likely involve spray foam.

Good info can be found at buildingscience.com

[s.kelly]

Almost forgot, generally speaking the "radiant barrier" is way overpriced for the minor increase in performance. Much much better to add insulation or seal air leaks. This stuff is nothing more than tin foiled bubble wrap with a misleading marketing campaign. Do a little web research on green building sites or building science, not a radiant barrier salesman though.

Havve you seen the All in the Family episode with the aluminum sidingg salesman preaching its insulative value? Same salesman 30 years later.

[Accolay]

Thanks for your responses.

It would only be a "living space" in the idea that the temperature would be comfortable to walk up there for any length of time. I understand what you're saying about the load bearing potential of the floor joists. I'm not looking to convert into another room, just a clean space I can store some boxes, maybe Chirstmas decorations. I'm fairly certain the joists are able to support the few hundred pounds I propose, but I probably wont put plywood over the entire floor. It would sure make running wires much easier too.

Do a little web research on green building sites or building science, not a radiant barrier salesman though.

Ha! Thanks for that. I'm never one to jump along with the bandwagon on anything-especially from salesmen...if that were the case, I would have already torn out all of my old windows and put in pocket replacements. The same reason I don't quite buy into the spray foam idea....talk about expense....and funny I can't find anywhere that mentions how long it lasts-does it break down? Some sites mention they are stable "over time" but how long is that these days...20 years? I've already read that the bubble wrap insulation isn't as effective as the foil type barrier, but I'm still exploring this possibility. So far it looks like about $120 in foil to do my attic.

The house has already been given soffet venting...but I am concerned about trapping moisture. I'm looking into foam baffles. Either way, I'm fairly sold on getting rid of the old insulation---I have a lot of wires to run since I'm also sold on rewiring the house (why would someone tear out all of the plaster walls, then not take out all of the old knob and tube? Oh... those are the same people who decided not to connect the plumbing vent to the main stack, and leave the old tub drain open/dead ended under the sub floor. But I digress).

[steponmebbbboom]

the most important detail to consider when giving advice on insulation is the geographic location of the house. Where are you located?

[downtowndahlgren]

I just had all the old insulation sucked out of my attic and replaced with new. There was no way I was planning to mess with the old stuff even with a mask, since there were several layers and it was all gritty and dirty, and of unknown origin on the lowest layer. The removal even took out small rocks and pieces of brick from the old chimney. Installing the new insulation involved styroam baffles, as well as constructing cardboard barriers around the air handler, ducting, and the area of plywood flooring around the top of the attic stairs, then blowing in R-32 insulation. Well worth it!

[Accolay]

Where are you located?

I'm in Minnesota. According to this chart, I would need anywhere from R49-R60 if I take all the old stuff out: http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table

I just had all the old insulation sucked out of my attic and replaced with new.

How big is your attic and how much did it cost, If I can ask.

[downtowndahlgren]

The total was $4200. They also disinfected the attic, pest-proofed it, and put a walkway to the only remaining original window down for me so I could do restoration work from the inside. They were also very considerate about allowing time for my electrician to examine and repair any wiring problems before installing the new insulation. It was NOT cheap, I realized that; however, there was no way I could do it alone, or even with the help of my handyman.

[mross_pitt]

Is there really any value to getting rid of the existing insulation(...unless maybe if it was wet)? It seems like extra expense without any real benefit. Why not just add new over old? It may be old and ugly but it's still insulation.

And... using cardboard to build barriers? Is it really cardboard? Isn't that poor workmanship?
That would be an invitation to mold, a potential fire hazard,etc.