Covering insulation in attic

[Bollox]

I'm about to lay some insulation (fibreglass) in an attic space and I want to cover it on the top side, as it gets pretty dusty and nasty up there and I would rather keep all the bugs and crap from getting in the insulation.

Any suggestions on what to cover it with? My first thought was to use Tyvek or one of the other house wraps but I guess it should be something that breathes to avoid condensation issues. Eventually I'll probably put down a subfloor up there, but not right now (too many other projects in the works).

Thanks
Mike

[Hoover]

Tyvek is used on the exterior of the house to allow moisture to escape, and to cut air infiltration to the interior.

[Bollox]

Tyvek is used on the exterior of the house to allow moisture to escape, and to cut air infiltration to the interior.

So wouldnt that be a good material to cover the insulation with?

Mike

[parnelli]

So wouldnt that be a good material to cover the insulation with?

Mike

I vote no. It would seem to me that you would have just a good a chance at trapping moisture below the cover (be it tyvek or anything) as you would keeping stuff out of the insulation.

In cold climates the vapor barrier should be to the heated side- while Indy isn't Northern, I would think it's cold enough there for the same rule to apply.

[eltigre]

I also vote no. Wet insulation is no fun (unless you area mold spore)

[Bollox]

My thought with the Tyvek is that in the walls the Tyvek is on the outside (cold) side of the insulation, so why is it any different in an attic?

[JSCOOK]

Forget the fiberglass insulation altogether ... IMO it's old technology and there are much better products to use, especially in this application.
There is a product that is made up here in Canada and exported to the USA called "ROXUL" and definitely insulates better based on cavity depth, water has no real affect on it as I've actually seen it "bead" and run off the insulation, it's semi-rigid and cuts easy with a old bread knife ... and it can be used in some really nasty locations without any issues

The other thing to remember is that any sort of a "barrier"should be applied on the warm side, not the cold side of the insulation ... insulation in attics are typically not covered with anything as the roof "should" provide adequate protection for the insulation ... I've done countless installs with Roxul and never had any issues ...

Check out: http://www.roxul.com/sw16796.asp

[dlminehart]

I'd avoid the fiberglass if possible. If your attic isn't really tightly sealed, fibers will get down into the house, where they'll be inhaled and embedded permanently in your lungs. Better to use cellulose, which has an almost equivalent R-value, lacks the microscopic fibers, and stops air movement through the insulation, unlike fiberglass, making it actually more effective (convection plus conduction) than fiberglass.

[Russianwolf]

I won't get into the type of insulation battle, but how about using landscaping fabric? moisture and air can go through it, but it should keep stuff from falling into the insulation.

[LinuxRandal]

Forget the fiberglass insulation altogether ... IMO it's old technology and there are much better products to use, especially in this application.
There is a product that is made up here in Canada and exported to the USA called "ROXUL" and definitely insulates better based on cavity depth, water has no real affect on it as I've actually seen it "bead" and run off the insulation, it's semi-rigid and cuts easy with a old bread knife ... and it can be used in some really nasty locations without any issues

Had to laugh at fiberglass being listed as old technology. My house was built before codes, and has rock wool insulation in the old attic. People used to call it nasty stuff. Gramps used to work for owings corning, and I had heard about the pink stuff that used to blow across the parking lot. A person (don't know official term) I spoke to after a neighbors fire, said besides all the asbestos, these houses were built with, that fiberglass would be the next thing that would get banned. He talked about how our "new" (at the time) state law requiring abatement, would cause any homeowners to go bankrupt, due : the lead paint, the asbestos in our siding, left over from the heating and cooling, and in the old wiring, and the fiberglass when it gets banned.

The problem with any of it, fiberglass, asbestos, rock wool, celulose, is people DON'T take responsibility for themselves and wear protection. I realize that when a product is new, we don't know the risks, but as we have more of these type of products, we should start anticipating problems.
rant off, thanks for the laugh.

[scorrpio]

There are different kinds of barriers. The one that backs insulation batts generally is not permeable and is installed towards interior, usually right under the drywall. Its purpose is to stop interior air moisture from condensing in the insulation. However, Tyvek is not that kind of barrier. Tyvek goes on top of wall sheathing, It is semi-permeable so that any rain water getting under siding would run off it, but any moisture that finds its way under the wrap is allowed to escape - so it does not rot the sheathing. If you really want to cover it, Tyvek should work.

When you lay the batts in your attic, be sure that you have the vapor barrier installed right up to ceiling drywall. Moisture from interior should concern you a lot more than from outside.

Now, if you have problems with moisture and bugs in your attic, you REALLY ought to take a good look at its ventilation and roof condition. Rotted trusses are not any better than wet insulation. My attic insulation got no cover on it except in sections where plywood floor was instaled, and it stays bone-dry and clean even during wettest months.

[vaking]

I am a little confused here as to what you want to do.
Are you putting insulation under the roof with the attic space being on the warm side or on top of the ceiling with attic space being cold and planning to put floor over that insulation eventually?
My house has an original old part and a new addition. I have warm attic in old part and cold attic in addition, so I have both of those setups. In the original house insulation (fiber) is covered with hardboard, so you don't breathe that fiber when you are in the attic. Does the job and easy to do. In the addition pitch is very low, there is no floor and insulation is not covered.

[Bollox]

Sorry, in my first post I wasnt very clear what I wanted to do.
I have put a ceiling over the second floor of my 150 year old barn. Drywall, then unfaced fibreglass. The attic space I am talking about will be cold space.
I was wanting to cover the top side of the fibreglass with something to stop dust, dead bugs, or droppings from the occasional bat from ending up in the insulation. I realise that whatever I use will have to enable the house to "breathe", so as not to trap any condensation or moisture from summer humidity inside the insulated ceiling. There arent any roof leaks or major sources of moisture.
Eventually I'll probably lay down a floor on the topside, but right now I dont need the space, and have plenty of other things to spend time and money on.
Maybe its not necessary to do anything at all, but I have noticed that stuff that we stored up there did get a little dusty.
Thanks for all the advice
Mike

[dlminehart]

Mike, the biggest problem is not summer but winter humidity. Cold air doesn't hold as much moisture as warm air. The warm air in your house is relatively humid compared to the cold winter air in the attic. When the warm moist air rises into the attic and cools, it can't hold the moisture anymore so it condenses where it's cooling. This is usually near the top of your insulation, on your rafters, etc. Implications: most important to minimize cracks allowing air to rise from house into attic before putting down the insulation, then keep attic well ventilated in winter to move any moist air out before it can condense.

[scorrpio]

I have put a ceiling over the second floor of my 150 year old barn. Drywall, then unfaced fibreglass. The attic space I am talking about will be cold space.

Bad, bad, BAD!!! I'd lift that fiberglass out, get batts faced with a barrier, lay them barrier down on the ceiling drywall, and put the unfaced fiber back above those. Interior moisture must not be allowed in the insulation.