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Blown in attic insulation

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Dec 02, 2013, 09:13 AM
Blown in attic insulation
Here is my question:

I currently have a house that was built in the 60s and when I bought the house there were signs of mice or rats or some other pests that were getting in thru the crawlspace vents. I have fixed that problem and am now wanting to tackle the lack of insulation issue. There is poop in the insulation, is it ok to just blow in the attic insulation from a box store on top of the insulation or should I have the old insulation completely removed.

Dec 02, 2013, 02:31 PM
it would be a good idea to shovel out then vacuum out the old insulation.

before you start... put on disposeable gloves, and dig a little to the bottom. if you come across grainy, shiny stuff, get the ! out of there, it's vermiculite. this freely releases the worst kind of chrysotile asbestos when disturbed, and it is absolutely critical that a professional asbestos removal company get rid of that junk safely. it's a life hazard as long as it's in the house.

if you just have cellulose or batt insulation, you can safely remove the old stuff with a respirator on (for the mouse excrement) and long sleeves, eye protection, and gloves. change in the garage, and wash the work clothes in a separate load with bleach.

sig: if this is a new economy, how come they still want my old-fashioned money?
Dec 02, 2013, 03:29 PM
I would get rid of the old, if the mouse issue was extensive, and lots of evidence throughout the attic. Only in one area? Just get THAT stuff out. Go with the max recommended r value for your zip code too, and make sure you have the right amount of ventilation since you are adding insulation depth.

Myself, I would always opt for rolled/bat insulation over the loose filled. It may cost a little more, but if you ever need to get to the ceilings below (from up there) to run wiring, or cable or change out/add much easier to either flip or roll it out of the way to see the horizontal ceiling supports to crawl around up there. It often involves two layers, one with a vapor barrier to set between the joists and the next un faced layer across the other direction. Less chance of accidentally covering up any eave vents too.
Dec 02, 2013, 06:58 PM
I am going to disagree.

Sure, mouse poop is gross. Coming in contact with lots of fresh, mouse poop is not a good idea. But if the mouse problem has been solved then there is no new additions. What is there will quickly dry out and not be a problem.

The only way to get rid of the poop will be to vac up every bit of insulation that is currently in there. As far as exposure to any poop goes, this process will carry a much, much higher element or exposure and risk to you. The dried poop that is on the top side of your ceiling drywall is not going to leach through. Any odor is long gone.

I would feel very comfortable by adding new insulation above the old and leaving it at that.

Dec 03, 2013, 07:57 AM
I too would leave the present insulation in place and add blown in insulation to a desired depth and R value. All the work and mess of removing what is present is not worth the price of the amount of new insulation needed. To hit the R value, which is a R38 {new construction number} in these parts where ever you purchase your supplies can guide you on what is needed.
Baffles can be installed to protect soffit vent openings. All insulation will compress to some degree, not much difference if all new or an existing/additional set up. Proper gable venting or more importantly roof peak venting is paramount.

This message has been edited. Last edited by: CommonwealthSparky,

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