The Great Crawlspace Challenge - Building & Construction - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 09-17-2011, 06:29 AM   #1
Newbie
 
Join Date: Aug 2009
Posts: 6
Rewards Points: 10
Default

The Great Crawlspace Challenge


Lots to cover, so bear with me. Bought my rebuilt house 5 years ago. The original foundation is 50 years old, but this has an additional foundation added 5 years ago. To the best of my knowledge, there has been no sump pump or drainage installed ever. After several years of heavy rains, and recently Irene, I can't wait to fix this any longer.
Situation:
Entire basement is a crawlspace. Both foundations are cinder block. Original foundation floor is coarse gravel with an old vapor barrier which comes to within a few inches of the walls. Newer foundation is poured concrete floor. No vapor barrier. There is a space cut out of the original basement foundation wall to access the rear basement. Both basement areas are fairly flat, with the concrete floor one being about an inch higher. In heavy rain situations (Irene put about 8-10 inches under there), the water rises and sit under the vapor barrier which pushes up. Very high water table here. Eventually the water level goes down. Gravel crawlspace is now dry, but there's about a quarter of an inch of water in the concrete floored space.
I am going to install a sump pump soon, and have some specific questions. Any additional comments are welcome.
1- Vapor barrier- can someone recommend a new one? Do I need to do a complete cover-the-walls encapsulation?
2- Concrete area- how do I create a sump pit in there, when you can't get a jackhammer into the low crawlspace. How do I get the water from there into the gravel crawlspace?
3- Pump location. Crawlspace has outside access on one side. This side would be good for the pump, but this side is where my water and gas lines come in. Is it too much of stretch to put the pump on the side with the opening (for easy access), then run horizontal pipe across the width of the house (35+ feet) to drain?

I'm sure there's more, but that's just my initial thoughts. Thanks for reading this lengthy tale. Pictures probably tomorrow...

Advertisement

casualfc is offline   Reply With Quote
Old 09-17-2011, 08:05 AM   #2
Member
 
Join Date: Mar 2007
Location: Long Island, NY
Posts: 9,519
Rewards Points: 2,000
Default

The Great Crawlspace Challenge


The thickness of the concrete in the crawlspace is probably about 2" or so. You can take a circular saw and cut out the perimiter of the sump pit and hammer out the middle.
I'd put the pit at the lowest point on the slab. If there isn't one, I'd put it in the middle of the room.
I personally don't like to run the vapor barrier up the walls. The walls get moist and it bring that moisture closer to the sill. It also masks the walls, so it's hard to see if termite mud tunnels are there. Even with clear plastic.

Advertisement

__________________
Ron
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
B. Franklin 1759

Last edited by Ron6519; 09-19-2011 at 01:40 PM.
Ron6519 is offline   Reply With Quote
Old 09-19-2011, 01:13 PM   #3
Below Grader
 
Join Date: Jul 2008
Location: Seymour
Posts: 68
Rewards Points: 75
Default

The Great Crawlspace Challenge


You might need to do some grading to make sure the water runs to the sump pit, or better yet, install a drain pipe around the perimeter of the crawl to collect water and divert it to the pit.
That should take care of the water intrusion problem.

As for the vapor barrier question. Crawl Space Encapsulation is highly recommended by all of the most reputable building science and green building organizations, as well as the US Department of Energy. Not only to control moisture in the crawl space and prevent mold and structural decay, but to improve a home's energy efficiency.

There is however a lot of misconception concerning crawl space encapsulation. The process goes way beyond lining floor and walls with a poly sheet. It includes completely sealing the vents, and air sealing the space to prevent outside air moisture to get into the crawl.

You will then need to deal with condensation and condition the crawl by installing a dehumidifier or a crawl space conditioning system, which blows air from upstairs into the crawl.

It is also a good idea to avoid generic materials and look for a professionally developed and installed crawl space encapsulation system. These systems include features like puncture resistant 20mil liners, antimicrobial treatment, UV protection, air tight sealed vent covers and access doors, as well as clear caps to facilitate termite inspections.

It is also good to mention that a clean, dry crawl space is not so inviting to termites and carpenter ants, which are commonly attracted by moist, soft wood. And if they get there, a bright encapsulated space is much easier to access for periodical inspections than a dark, moldy, dirty one.

Even with a running dehumidifier, a professionally installed crawl space encapsulation system can save you around 18% in heating and cooling costs. Much more than that if you have air ducts running through the crawl.
CyFree is offline   Reply With Quote
Old 09-19-2011, 01:51 PM   #4
Member
 
Join Date: Mar 2007
Location: Long Island, NY
Posts: 9,519
Rewards Points: 2,000
Default

The Great Crawlspace Challenge


Quote:
Originally Posted by CyFree View Post
There is however a lot of misconception concerning crawl space encapsulation. The process goes way beyond lining floor and walls with a poly sheet. It includes completely sealing the vents, and air sealing the space to prevent outside air moisture to get into the crawl.

You will then need to deal with condensation and condition the crawl by installing a dehumidifier or a crawl space conditioning system, which blows air from upstairs into the crawl.


It is also good to mention that a clean, dry crawl space is not so inviting to termites and carpenter ants, which are commonly attracted by moist, soft wood. And if they get there, a bright encapsulated space is much easier to access for periodical inspections than a dark, moldy, dirty one.

Even with a running dehumidifier, a professionally installed crawl space encapsulation system can save you around 18% in heating and cooling costs. Much more than that if you have air ducts running through the crawl.
I don't understand a ferw of the points you made.
Crawlspaces need to be vented by code. I don't see a seasonal sealing methodology, just a blanket statement to seal them up.
Termites stay in the earth or earth like environments(mud tunnels). If you cover the floor and the walls to the sill, you basically provide a perfect environment for the termites to get from the ground to the wood without exposing them to the "dry" conditions above the plastic.
I can't see sealing one crawlspace in a house getting you an 18% savings in heating and cooling on your utility bill.
Where did you get this figure?
__________________
Ron
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
B. Franklin 1759
Ron6519 is offline   Reply With Quote
Old 09-19-2011, 04:34 PM   #5
Below Grader
 
Join Date: Jul 2008
Location: Seymour
Posts: 68
Rewards Points: 75
Default

The Great Crawlspace Challenge


True some codes still ask for crawl space vents, but some building scientists found to be a scientific fallacy:
http://www.rlcengineering.com/csfallacies.htm

Some codes now allow for complete sealing of the crawl space, year round, provided that it is conditioned. And slowly, more and more codes are changing the requirements.

http://www.buildingscience.com/docum...=crawl%20space

As for how encapsulated crawl spaces would help curb energy loss, it mostly has to do with the "stack effect".

Hot air inside a building, rises and escapes through the upper levels. As a result, a low pressure area is created in the lower parts of the building, causing new, unconditioned air to be sucked in from the crawl space or basement. That causes the HVAC system to work more than it should to keep up with heating and cooling that air. In addition, the moisture from the crawl space is also carried in, and humid air is harder to cool and heat.

It gets worse if you have uninsulated ducts running through the crawl because now you have the conditioned air that goes through the ducts being cooled or heated by the crawl space's temperature, and often these ducts are not properly sealed, so there is also leakage.

According to Advanced Energy, energy loss through vented crawl spaces are so significant that you might as well forget all other attempts to reduce a home's energy consumption until the crawl space is fixed.

http://crawlspaces.org/

The above link has a ton of studies on crawl spaces with a lot of figures.

New energy efficiency and building guidelines all call for tighter and well controlled building envelopes and a vented crawl space is a huge, uncontrolled hole in any building envelope.

The following is taken from the Department of Energy - EERE Building America Best Practices series.

http://www.eere.energy.gov/buildings...s/db/35379.pdf

As for the termites, as I stated before, professionally installed systems are fitted with a cap to allow for inspection, which is also made easier by having a clean and clear crawl.

In dirt, vented and moldy crawl spaces termite problems can go unchecked for months because homeowners aren't exactly happy to crawl under the house to inspect it on a regular basis.

Pest control companies these days actually install crawl space encapsulation systems as part of their services.

Of course there are many who disagree with all of the above.

I usually consider my sources and when researching this, the ones I cited seemed quite credible to me. But I am always open to examine any evidence and different findings. This happens to be a subject I am really interested in and I know building science is ever evolving.

Feel free to point me to any sources you may know of!
CyFree is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Frost on crawlspace walls Red Squirrel Building & Construction 4 01-10-2011 03:13 AM
Floating floor in a crawlspace CO DIYer Flooring 0 01-02-2011 09:46 PM
conditioned crawlspace fan albertpinto HVAC 4 12-27-2010 05:46 AM
Drying out a crawlspace tmpyankee HVAC 4 12-12-2008 02:41 PM
Roof Venting Issue, crawlspace supton Roofing/Siding 1 11-12-2008 07:44 AM




Top of Page | View New Posts