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Old 12-16-2010, 09:02 PM   #1
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Attic insulation problem


Hi, I'm a first time poster -- and total diy novice, so please forgive my misuse of terms... We bought our first home last year and am trying to do as much as I can by myself, but finding a steep learning curve!

And now faced with an attic insulation problem.

When we bought the house, the home inspector noticed mold in the attic (unfinished, cramped, but there's crawling space). He said it was probably due to poor ventilation. We had the mold removed / remediated before we moved in (there's some white spray on the rafters and plywood now), but didn't do anything about the airflow because the mold guys said the airflow looked good (two vents, one on either side of the roof).

We've had a lot of trouble heating/cooling the second floor where we sleep, and my 3 yr old's room is especially cold at night. So I went up to look at the insulation in the attic. I noticed a few things:
  • we have old loose-fill fiberglass insulation
  • it's about 3 inches high, and uneven all around
  • it's damp
  • there's no vapor barrier underneath!
  • I think new mold is growing in a couple of spots on the plywood (backside of roof)

Putting those things together, it seems to me that the mold problem may be cause by our lack of a vapor barrier under the insulation, rather than airflow problem, as evidenced by the damp insulation... logical, right?

Am I correct in assuming that what I need to do is:
  1. remove all old insulation
  2. put down vapor barrier (we live in Chicago)
  3. re-insulate with something good like blown cellulose
  4. have that new mold removed
  5. check airflow -- there may be eve vents at the points where the roof meets the floor, but I can't tell because the insulation is pushed up against every corner; so check that and leave space if there are any eve vents

Concerns: Our attic is pretty small, hard to move around in (especially around the sides!), and I'm worried about the process of removing all that old yucky insulation and moving it through the house, especially because I figure it probably has mold in it and we have two little kids. Also, laying down new vapor retarder sounds like it's supposed to be a nightmare. And to top it all off, we are on an extremely limited budget. So while I'm a bit anxious about trying to do all this myself, I'm equally scared about what it would cost if I hired someone.

Many thanks, in advance, if anyone can give me any advice. Thanks so much.


Last edited by Dan77; 12-16-2010 at 10:16 PM.
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Old 12-21-2010, 09:57 AM   #2
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Attic insulation problem


Mold needs food, cellulose from wood and water from the water vapor in the air.
Water vapor, comes from cooking, washing, breathing and sweating.
Fitting extractor fans in the kitchen and bathroom, will get rid of cooking and washing water vapor, keeping the doors closed helps to stop the migration to other parts of the home.
Opening the bedroom windows a small amount for perhaps ten minutes in the morning will let wet air escape to the outside, where it is usually colder and drier, then cold dry air will come in and take the place of the wet air.
You can use a dehumidifier to collect the water vapor from the air,this will save opening the windows and loosing your warm air, but you will need some fresh air to breath.
You can paint the ceilings with oil based paint, that will help prevent water vapor from passing through the dry wall into the roof space. You can also search for holes and gaps in your walls, floors and ceilings that let your warm air out. These need to be blocked.
A modern home built to Passive House standard is built as an air tight box, to save energy. These come with a mechanical ventilation system.
The best way to stop water vapor from entering the roof, is to fit a plastic almost water vapor proof barrier between the dry wall and the frame of the home.
Once the water vapor is prevented from entering the roof space, you can forget the vents and block them.
This will stop the passing wind from sucking the warm air from your home, and extracting the heat that rises through the wood framing, thereby making your home cheaper to heat.
Fiberglass is a rubbish insulation, it is whats known as an open cell insulation, the air and water vapor move through it, when it turns cold, any water vapor in the fiberglass freezes and turns to ice, when it warms up it thaws and makes the fiberglass wet.
Water is a very good conductor of heat, it is 4,000 times better at moving heat than dry air.
Wet insulation strips the heat from your home.
Only use fiberglass in sealed plastic bags, to keep the air and water vapor out.
Wash the mold off with soap. Then kill with household bleach. Then use a hair drier to dry.
Mold cannot grow without water.
Note: All the air in the world is full of mold spores, as you can see it does not take hold and grow everywhere, it only grows where there is food and water, keep the roof dry, the mold dies.
Cellulose is not a good insulator, go for a closed cell insulation like polystyrene.
These are all things you can do yourself.

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Old 12-21-2010, 02:59 PM   #3
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Attic insulation problem


Quote:
Originally Posted by Perry525 View Post
Cellulose is not a good insulator,
Really???
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Old 12-21-2010, 03:17 PM   #4
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Attic insulation problem


Put simply. YES!
Modern closed cell insulation's like polystyrene (only brought to market by Dow 51 years ago) are far better in actual use.
When you have an open structure, the air moves through it, far more important water vapor can enter cellulose, freeze, thaw and make the insulation wet.
Water is 4,000 times better at transferring heat than dry air.

Polystyrene, can be immersed in water, covered in ice, it still retains the same insulation factor.
Happy?
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Old 12-21-2010, 11:48 PM   #5
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Attic insulation problem


Quote:
Originally Posted by Perry525 View Post
Put simply. YES!
Modern closed cell insulation's like polystyrene (only brought to market by Dow 51 years ago) are far better in actual use.
When you have an open structure, the air moves through it, far more important water vapor can enter cellulose, freeze, thaw and make the insulation wet.
Water is 4,000 times better at transferring heat than dry air.

Polystyrene, can be immersed in water, covered in ice, it still retains the same insulation factor.
Happy?
Delirious, thanks for asking. I realize of course that closed cell foam is superior. That wasn't the question. You said cellulose was not a good insulation and everything else I have read here says it's an excellent insulation, far superior to fiberglass and on a cost basis probably the best option in most cases. Thanks for setting the record straight.
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Old 12-22-2010, 03:35 AM   #6
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Attic insulation problem


Quote:
Originally Posted by Perry525 View Post
Opening the bedroom windows a small amount for perhaps ten minutes... Which also lets a lot of heat out, so keep it to a minimum. Another option is to use Panasonic fans on timers, with passive air inlets. Opening the window religiously may become a drag. Watch your humidity levels, and shoot for the recommended 7.5 cfm or air exchanges per occupant, plus 1 cfm for every 100 sf of living area. Air should be exhausted from wet/stinky areas, and introduced into bedrooms, living rooms; where you spend your time. An HRV or ERV is great at that, but so is strategically locating and using exhaust fans and passive air inlets.

You can paint the ceilings with oil based paint, that will help prevent water vapor from passing through the dry wall into the roof space. A latex vapor retarding paint can be used instead, too (about the same perm, or a tad less) and may have less VOCs in it; dunno that one.

The best way to stop water vapor from entering the roof, is to fit a plastic almost water vapor proof barrier between the dry wall and the frame of the home. Not necessarily "the best". Stopping air movement is the name of the game. Water diffuses about 1/100th as much as in travels in air leaks. That is why the airtight drywall approach works so well, and it allows the system (wall or ceiling) to breathe in both directions. Using poly (perm very low, about 0.06) in Chicago may not be a great idea. Poly is generally recommended only for very cold places, like upper Minn, Canada, Ak, etc. Even here in Frb, our code calls for "one perm or less", as does the code in Mn. The airtight drywall approach meets that code. Be very careful w/ a true vapor barrier, esp if you ever run an air conditioner. The AC will possibly have moisture condensing on the outside of the poly. Also, solar vapor drive can do the same thing. Buildings are being built to breathe much more than they used to be. Poly and breathing don't equate.

Once the water vapor is prevented from entering the roof space, you can forget the vents and block them. Excuse me? You can NOT perfectly stop the water. Roof insulation needs air moving over it to get the trace vapor out of it, or you WILL get wet insulation.

This will stop the passing wind from sucking the warm air from your home... Which is exactly what cellulose is good at, and fiberglass batts so poor at.

Fiberglass is a rubbish insulation... Roger that, but the dense packed Spider stuff is apparently pretty good stuff. Batts are terrible.

Cellulose is not a good insulator... Absolutely a false statement. Sorry about that, but cellulose is one of the best insulation materials on the market. Besides being relatively cheap; it is great at stopping internal air movement (and hence air through it); it can absorb miscellaneous water vapor in the heating season, then let it out during the warmer months (vapor buffering), which helps protect the wood, too; it has very low embodied energy, the opposite of plastic foam; it deters rodents and bugs (if treated w/ borates), which eps foam will NOT do (ask your local bug killer if ants love foam). Foam does not seal every little nook and cranny, and needs meticulous detailing to be air tight. It has its place, but it is by no means "the answer". Reported problems with cellulose are the result of poor workmanship, (probably poor air sealing) not the product. Poor workmanship will kill anything.
See after the bullets above, and anyone interested in reading more can go to buildingscience.com, greenbuildingadvisor.com, the ORNL site, etc.
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Old 12-22-2010, 05:41 AM   #7
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Attic insulation problem


First of all, thank you for reading my post and for writing such an interesting opinion.

My position is that, I am only interested in what works in every day life.

Results obtained in a lab are often false, in every day life professional workmanship and understanding is often poor, corners are cut, the DIY person will in most cases do a better and more careful installation.

The cost of the best solution is interesting, the thing that matters is the knowledge garnered world wide, other counties have spent more time and money over the last thirty odd years studying these things, they have often reached different conclusions, the position taken by many authorities here, is often bent to accommodate vested interests. The reader may and will make up there own mind and will then decide what they will do.

A few dollars saved on a cheaper commodity, is false saving, a building may well be in use for several hundred years, the better more costly commodity will pay for itself many times over in that period.

May I recommend that you look up "Passive House, USA" style and compare it with "PassivHaus institut Germany/European Union" to see what I mean.
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Old 12-22-2010, 02:10 PM   #8
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Attic insulation problem


I've read a lot about PH, and think they have a great goal in mind, and many ways to approach that goal. One thing, btw, I find questionable with their "usual" method (if there is such a thing) is the extreme use of eps under slabs. That particular fact is interesting, but I wonder about the ROI in most places. If you want "real world" opinions, then see greenbuildingadvisor.com. There are extremely knowledgeable people there who have been building for decades. If they are not real world, then no one is. I think you will see that the use of cellulose, if that is what you referred to as a "cheaper commodity", results in very long-term gains. I would not argue about the risks of translating lab testing directly to the field, but to say it is "false" is grossly over simplifying it. Lab testing is the science behind what is done in the field, which is where the lab situation is "duplicated", as best as can be, or totally botched up. If you ignore the science, then you are flailing around with anecdotal information, which is good, but never complete. IMO, study the science, then apply it correctly. The "study the science" part is not quick and easy, either. You can't read one article and then go build, as one article is only part of the equation. A house is a complex structure with a lot of science in it. Good luck to all.

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