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I am looking to add additional insulation to my crawlspace, noticed that the current insulation installed by the builder does not seem to be adequate and was poorly done (no option to have them come by and redo it again since it has been 3 yrs since we moved in).
The current insulation installed in the joists are unfaced R19, there is no insulation in the band joists and the crawlspace door is not insulated either. I also noticed that they didn't install any insulation where bigger pipes were coming down (numerous areas), joist insulation also starts a few inches away from the side walls so there are gaps all around the perimeter of the walls.
I am really surprised that it pass inspection given how the insulation was installed, I am thinking of adding additional insulation as follows:
Crawlspace Door - 2"-3" rigid foam board plus weather stripping around the edges (also helps keep bugs/spiders out)
Band Joists - R13 fiberglass
Joists - R19 fiberglass
There is a vapor barrier installed on the ground, my question is should the additional insulation be faced or unfaced? I don't have any water issues in the crawlspace since the ground grading slopes away on all four sides, I am inclined to use the same unfaced on the joists area (top) and faced on the band joists (sides).
My thinking is that any humidity that gets in afterwards at least let it have an opportunity to go somewhere (in this case up), if I use faced insulation all around then the humidity might be trapped between the vapor barrier in the bottom, band joists on the sides and joists at the top making my crawlspace a breeding ecosystem for mold.
Improving the insulation as you propose will be only a small incremental improvement.
If you have a vented crawlspace, you might consider an alternate approach as well.
Seal the vents.
Confirm that the gound vapor barrier is 100% coverage.
Add a dehumidifier with a drain to the outside.
My crawlspace now averages much higher than exterior ambient temperatures.
In the coldest weather this winter, my crawlspace never dipped below 59°.
The warmer your crawlspace, the less the insulation matters.
It is common in modern fully-conditioned crawlspaces to have no insulation at all in the floor.
The warmer your crawlspace, the less the insulation matters.
It is common in modern fully-conditioned crawlspaces to have no insulation at all in the floor.
One of neighbors back home built a new home with a modern crawl space. I was blown away by how dry and clean the space was. Down right comfy.
Improving the insulation as you propose will be only a small incremental improvement.
If you have a vented crawlspace, you might consider an alternate approach as well.
Seal the vents.
Confirm that the gound vapor barrier is 100% coverage.
Add a dehumidifier with a drain to the outside.
Sealing the vents sounds fairly straight forward and easy to do, my vapor barrier probably provides 98% coverage (small gaps around/near the cement blocks here and there). I would need to "patch" those areas and tape them to get 100% coverage, will that work or should I replace the vapor barrier completely?
Granted the original install my have been somewhat lackluster, but the amount of money (time is "money") that you'll spend repairing will never be recouped unless your in the house about 25yrs.
I'd just concentrate on the vapor barrier- the SE can be brutal with humidity.
Sealing the vents sounds fairly straight forward and easy to do, my vapor barrier probably provides 98% coverage (small gaps around/near the cement blocks here and there). I would need to "patch" those areas and tape them to get 100% coverage, will that work or should I replace the vapor barrier completely?
Unless the vapor barrier is very new and clean or you spend a lot of time cleaning it, it’s likely the tape will not stick very well.
Just as an FYI for everyone else. This was moved from the North Carolina forums. Crawlspace design and treatments are going to be very different in various areas of the country, depending on typical humidity, longer winter or summer and typical temperatures. What works one place will not necessarily apply somewhere else.
Sealing the vents sounds fairly straight forward and easy to do, my vapor barrier probably provides 98% coverage (small gaps around/near the cement blocks here and there). I would need to "patch" those areas and tape them to get 100% coverage, will that work or should I replace the vapor barrier completely?
Like Sherifftruman says, it may be hard to get the tape to stick.
I don't think I would remove the old one though. Depends on how many piers you have under the house, and how much issue it would be to roll out the new.
I have done a 1500SF simple ranch house in under an hour, but I have three rows of piers, with offset alignment under my current house.
Mine is not 100% coverage, unfortunately. Maybe 98%--99%. But, my crawlspace is warm and dry.
If I add on, I will go over the old material.
I would probably add new on top, with a wide overlap, maybe 2-3', on the old vapor barrier in those areas.
You can pin the vapor barrier down to the dirt with old wire coat hangers, bent into a "U," and should be adequate.
It doesn't have to be a perfect seal. Just a torturous path for moisture to come into the crawl. A good dehumidifier will do the rest.
I agree with Mike. Having a conditioned crawlspace is so much more energy efficient, warmer, and provides prevention against mold. A good dehumidifier will also run at lower ambient temperatures (I think mine operates to almost freezing) and will really take the moisture out of there (I have to deal with an incredibly high water table.) I do have insulation in my crawlspace though, because the temps here can get down to single digits in the winter, and I have antique wood floors that can get cold.
If you are just going to address the vapor barrier instead, I would recommend that you replace it with a heavier one, and take it to 100% coverage including up the walls a bit and taping it there, as well as wrapping it around any support posts or piers and taping it. Mine is so heavy that repair people can crawl around on it and not damage it, and the bright white color really makes the crawlspace look a lot brighter even without lights in there.
1930 brick house in GA, existing vapor barrier that's probably 90%? Maybe less as I ended up doing a lot of electrical and plumbing where it shifted. I sealed the vents, graded the outside to keep water from the foundation, fixed gutters and added a $70 el-cheapo dehumidifier (oh, and box-fan). This past winter was colder than normal for Georgia, I never saw temps below 55 in my crawlspace. Even when we had the week of temps that didn't go above freezing. Humidity never drops below about 55%, but that's a function of the dehumidifier and typically 5~8% lower than my living space (currently it's 13% lower than my living space, shoulder season with no heat/AC to dehumidify and I'll get into the 80% range) ~ the fact that the condensation and rot issues the house had when purchased are no longer in evidence is good enough for me for now.
I'll dump the $2000 into a Proper dehumidifier and full coverage vapor barrier probably next year. Too many other things that are more important, like fixing my billion original windows.
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