U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > U.S. Forums > North Carolina > Raleigh, Durham, Chapel Hill, Cary
 [Register]
Raleigh, Durham, Chapel Hill, Cary The Triangle Area
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
 
 
Old 10-16-2013, 05:26 PM
 
Location: Near Falls Lake
2,306 posts, read 1,679,696 times
Reputation: 2148

Advertisements

Quote:
Originally Posted by C_Lan View Post
As a person that hates spiders, yeah...I'll opt for the 15mil stuff so that I don't have to do it again.

The points about water intrusion are very good. When i redid my crawlspace I also re-sloped my soil near the foundation and ran tubes from my downspouts under my mulch and to the front of my house where it drains down my lawn away from the house. I also installed gutter guards that have done a great job in keeping leaves and pine needles from clogging my drains. This has helped keep the foundation area much drier than before.
Properly functioning gutters and a positive soil grade are the first lines of defense to keep water out of the crawlspace/basement!
Quick reply to this message

 
Old 10-16-2013, 07:09 PM
 
16 posts, read 44,121 times
Reputation: 10
Thank you C_Lan and Carcrazy67.

No, I don't have a water issue, we have gutters and a french drain in place. My main issue is the sweating during summer month on ducts, HVAC unit and on the top of the 6mil plastic barrier, but no puddles, its pretty wet, the dirt underneath is damp. Had some mold, but it was minor, just few spots, washed and cleaned. Discarded all storage cardboard boxes that were wet and moldy.

I need that moisture out of the crawl space. If after putting down the 15 Mil vapor barrier will prevent the sweating, we would prefer to keep the vents open, due to concern about the the HVAC unit. I was wondering if closing the vent during high humidity months and opening it up for the winter would work.

Thanks!
Quick reply to this message
 
Old 10-16-2013, 08:00 PM
 
Location: Near Falls Lake
2,306 posts, read 1,679,696 times
Reputation: 2148
The vapor barrier will in itself not stop condensation. In fact, it can allow water to sit on top of the barrier-undesirable. The dirt underneath will almost always be damp unless it is well-drained soil (sand). This dampness is normal. Don't ever store cardboard or cellulose based products in the crawl-conducive to wood-destroying insects.

No reason to keep the vents open during the winter. Conventional thinking for a very long time suggested opening the vents in the summer and closing in the winter to avoid the possibility of the water supply lines freezing. The only reason to keep any of the vents open during the summer would be if there is a combustion air issue with a gas furnace. There are specific calculations for the amount of combustion air that is necessary-probably beyond the scope of the average home owner.
Quick reply to this message
 
Old 10-16-2013, 08:14 PM
 
256 posts, read 340,668 times
Reputation: 398
nc6588, you should check with your HVAC pro to determine whether your furnace requires venting for combustion air. If it does not, and you get the go ahead from your HVAC pro, seal up the vents. If it does require venting, you can install a duct line from one of your vents to the furnace for your combustion air. The vent can be the insulated flex type, terminated near your furnace, in a J shape to keep cold winter air from pouring into your crawl space. Another option is installing a damper to open when the furnace kicks on. This way, your fresh air supply stays closed unless the furnace is running, keeping out humid air during summer and cold air during winter.
Quick reply to this message
 
Old 10-16-2013, 09:51 PM
 
982 posts, read 2,145,594 times
Reputation: 770
We had a pest control service put down an extra thick moisture barrier because the moisture readings were a little high during hot humid weather.

That was several years ago.

We keep foundation vents closed during hot humid months and open them up during the fall and winter months when there's little humidity.

The readings have been average in hot humid weather and low otherwise. It's been years and same readings year after year.

best,
toodie
Quick reply to this message
 
Old 10-16-2013, 11:10 PM
 
16 posts, read 44,121 times
Reputation: 10
Toodie, thank you for sharing.

Thank you all.
Quick reply to this message
 
Old 10-17-2013, 09:42 AM
 
Location: Near Falls Lake
2,306 posts, read 1,679,696 times
Reputation: 2148
Quote:
Originally Posted by toodie View Post
We had a pest control service put down an extra thick moisture barrier because the moisture readings were a little high during hot humid weather.

That was several years ago.

We keep foundation vents closed during hot humid months and open them up during the fall and winter months when there's little humidity.

The readings have been average in hot humid weather and low otherwise. It's been years and same readings year after year.

best,
toodie

The installation of a "thicker" vapor barrier in itself will not solve humidity issues if you had a vapor barrier in good condition to begin with!
Quick reply to this message
 
Old 10-17-2013, 03:50 PM
 
Location: Holly Springs
3,861 posts, read 9,277,878 times
Reputation: 2995
A few points here:

- Condensation "sweating" has little to do with the vapor barrier provided you have basic coverage. Humid air reacting with the cold ducts and plumbing is what causes sweating, a lack of vapor barrier will certainly add to the humid environment from rising ground moisture, but like I said, with basic coverage that is nullified. When running your a/c, the ducts all leak to some degree pulling crawlspace air into the house. This creates a negative air pressure in the crawlspace brining more humid air in from the outside. With the a/c back off, the air pressure balances and that humid air that was brought in sits stagnant reacting with cool surfaces. Crawlspaces tend to be low and compartmentalized from the ducts so air flow can be very limited. Mold spores naturally occur on about everything and the excessive moisture gives them fuel to grow. The subfloor insulation acts like a sponge for this moisture holding it directly to the wood.

- If your furnace air intake needs to be extended, it is easy and cheap. It takes about 15 minutes and $15 worth of materials.

- UV light and direct contact with a moist ground does deteriorate vapor barrier over time, but 6 mil still typically lasts 10-15 years. There are much nicer products such as 10-20 mil barriers, but the cost escalates quickly. A typical house with 6 mil vapor barrier can be installed by a business for about $500. If you want reinforced 12 or 20 mil with taped seams and brought up the walls/piers, expect triple the cost. To attach the barrier to the walls, and we have done this a couple hundred times, drill 1/4" holes in the block every 18" and use plastic push pins (sometimes called Christmas Tree pins). That holds the weight of the barrier and butyl tape or other sealants form the seal to the wall. On the piers, use saran wrap first and then cover with barrier. The tape will stick to the saran wrap quite well.

- Just seal the vents permanently. Use a dehumidifier, preferably a commercial unit with that size footprint for efficiency and longevity. If the vents are sealed, there must be a mechanical means to control ambient moisture.

- Upselling is alive and well in the waterproofing/environmental/energy efficiency industries. There are plenty of products to separate you from your money, and plenty of salesmen that know how to follow a script, but lack the background to correctly determine why a situation is occurring. There is no replacement for experience, and you will find if you get multiple quotes that the solutions are boilerplate (and often shockingly expensive)

- As Carcrazy mentioned, there are plenty of encapsulated crawlspaces that do not perform as advertised. This is from an energy efficiency and moisture control standpoint. If you are interested in better energy efficiency there is a long list of upgrades you should make before getting into the crawlspace environment. Most energy loss is through the roof and windows, so address that first. If you are building a house, an encapsulated crawlspace would likely be a good investment as it is far cheaper to do during construction. Retrofitting can be very costly and quite difficult with the obstructions. I hesitate to recommend it on existing houses as I just do not feel the payoff is worth the payout. This opinion has been formed over the better part of 10,000 inspections, several hundred crawlspace repairs, significant reading, courses, seminars, and general study over the last two decades.

The best solution is to do what is necessary, stop there and see how it reacts to determine if additional steps are necessary. Anyone that stumbles onto this thread is more than welcome to message me with questions.
Quick reply to this message
 
Old 10-17-2013, 08:13 PM
 
16 posts, read 44,121 times
Reputation: 10
Thanks, Sacredgrooves.

Is it good idea to put new 15 mil on top of the current 6 mil(holes and torn on some parts), or do we need to pull it out, considering mold might drop on the plastic while cleaning the floor joist?

Thanks!
Quick reply to this message
 
Old 10-17-2013, 10:48 PM
 
Location: Holly Springs
3,861 posts, read 9,277,878 times
Reputation: 2995
I would recommend pulling the old barrier out after cleaning the floor joists. It would also be a good idea to fog the crawlspace with fungicide after cleaning the joists just to kill all the spores that are kicked up into the air during the cleaning process as well as on other surfaces. You can rent the foggers from Home Depot and they also carry the fungicide ( Eliminate, Clean & Prevent Mold with Concrobium Mold Removal Products)
Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


 
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:


Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > U.S. Forums > North Carolina > Raleigh, Durham, Chapel Hill, Cary
Similar Threads
Follow City-Data.com founder on our Forum or

All times are GMT -6.

2005-2018, Advameg, Inc.

City-Data.com - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 - Top