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WATER ENTRY IN BUILDINGS

AGE of MOLD - Old is the Mold?

BASEMENT CEILING VAPOR BARRIER
BASEMENT MOLD WATER IMPACT
BASEMENT WATERPROOFING
BRICK WALL DRAINAGE WEEP HOLES
BUCKLED FOUNDATIONS due to INSULATION?
BUILDING DAMAGE ASSESSMENT & REPAIR

CONDENSATION on WINDOWS & SKYLIGHTS
CRAWL SPACES

DEW POINT TABLE - CONDENSATION POINT GUIDE

EFFLORESCENCE, Salts & White / Brown Deposits

FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOD DAMAGED FOUNDATIONS
FLOOD VENTS & FLOOD PORTS
FLOODS IN BUILDINGS-mold
FLOOR DAMAGE DIAGNOSIS
FOOTING & FOUNDATION DRAINS
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION CRACKS & DAMAGE GUIDE
FOUNDATION WATERPROOFING
FRENCH DRAINS
FREEZE-PROOF A BUILDING
FROST HEAVES, FOUNDATION, SLAB

HUMIDITY LEVEL TARGET

ICE DAM PREVENTION

MOISTURE CONTROL in BUILDINGS
MOLD INFORMATION CENTER
NOISE / SOUND DIAGNOSIS & CURE

ODORS & SMELLS DIAGNOSIS & CURE

SEWAGE BACKUP, WHAT TO DO
SEWAGE BACKUP TEST & CLEANUP
SEWAGE BACKUP PREVENTION
SEWAGE PUMPS
SEWAGE PUMP CLOG DAMAGE
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
SUMP PUMPS
SWEATING (CONDENSATION) on PIPES, TANKS

TERMITES
TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES

VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS

WATER ENTRY in BUILDINGS
WINTERIZE A BUILDING

More Information

Wet basement cure: interior drain system (C) Carson Dunlop Associates Guide to Using an Interior Perimeter Drain to Stop or Prevent Basement Leaks & Water Entry
     

  • Definition and illustration of interior foundation perimeter drain systems to stop basement or crawl space water entry
    • Sketches and photographs of basement de-watering systems
    • B-Dri and Beaver Basement type basement dry-out system photos & explanation
    • Definitions of french drain, footing drain, perimeter drain
    • Foundation waterproofing methods
  • BASEMENT De-Watering Systems
  • BASEMENT LEAKS, INSPECT FOR - separate article
  • CRAWL SPACE DRYOUT PROCEDURES - separate article
  • FOUNDATION WATERPROOFING: CRACK SEALANTS - separate article
  • FOUNDATION WATERPROOFING SEALANTS - separate article
  • GRADING, DRAINAGE & SITE WORK - separate article
  • WET BASEMENT PREVENTION - separate article
  • Questions & Answers about interior perimeter drains for basement water entry control
  • References

Click to Show or Hide Related Topics

  • WATER ENTRY in buildings - home
  • ATTIC LEAKS Moisture or Mold
  • BARRIERS, EXTERIOR WATER
  • BASEMENT CEILING VAPOR BARRIER
  • BASEMENT De-Watering Systems
  • BASEMENT HEAT LOSS
  • BASEMENT LEAKS, INSPECT FOR
  • BASEMENT WATERPROOFING
  • BASEMENT WATER ENTRY PREVENTION
  • CATCH BASINS
  • CHIMNEY LEAKS
  • CONDENSATION on WINDOWS, SKYLIGHTS
  • CORROSION in ELECTRICAL PANELS
  • CRAWL SPACE DRYOUT PROCEDURES
  • DEW POINT CALCULATION for WALLS
  • DEW POINT TABLE
  • DRYER VENTING
  • DRYWELLS, FRENCH DRAINS for FLAT SITES
  • DRYWELL DESIGN & USES
  • EFFLORESCENCE, Salts & White / Brown Deposits
  • ELECTRIC PANEL MOISTURE
  • EXTERIOR WATER SOURCE ELIMINATION
  • FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
  • FLOOD DAMAGED FOUNDATIONS
  • FLOOD VENTS & FLOOD PORTS
  • FLOODS IN buildings-priorities
  • FOUNDATION DRAINS, INTERIOR
  • FOUNDATION WATERPROOFING
  • GEOTEXTILES & DRAINAGE MATS
  • GRADING, DRAINAGE & SITE WORK
  • GUTTERS & DOWNSPOUTS - home
  • HUMIDITY CONTROL & TARGETS INDOORS
  • HOUSEWRAP AIR & VAPOR BARRIERS
  • LOG HOME Leak Diagnosis & Cure
  • LOG HOME Condensation
  • MOISTURE in BUILDING WALLS, EFFECTS
  • MOISTURE in CELLULOSE INSULATION
  • MOISTURE CALCULATIONS
  • MOISTURE CONTROL in BUILDINGS - home
  • MOISTURE METER STUDY
  • MOISTURE PROBLEMS: CAUSE & CURE
  • MOLD in buildings
  • MOLD PREVENTION AFTER FLOODING
  • MOLD RESISTANT CONSTRUCTION
  • PERIMETER DRAIN SYSTEMS
  • ROOF VENTILATION SPECIFICATIONS
  • SOFFIT INTAKE VENTS & Attic Condensation
  • SEALERS, Basement Floor & Wall Moisture
  • SEWAGE BACKUP, WHAT TO DO
  • SITE & SURFACE DRAINAGE
  • SUMP PUMPS
  • SWEATING PIPES, TANKS
  • VENTILATION in BUILDINGS - home
  • WALL / WINDOW LEAK DIAGNOSIS
  • WET BASEMENT PREVENTION
  • WINDOW / DOOR AIR LEAK SEALING HOW TO
  • WINDOW FLASHING & SEALING
  • WINDOW LEAKS INTO BASEMENT
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Basement perimeter drains, French Drains, or B-Dri/Beaver Basement type basement de-watering systems: this article series discusses types of interior perimeter drain or what some call a "french drain" for stopping foundation leaks or preventing wet basements and crawl spaces. We describe the basic types of exterior and interior foundation drainage and de-watering systems for homes.

Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.

Basement Perimeter Drain Systems for Basement De-Watering: Installing & Inspecting "French Drains"

Basement de-watering system (C) Daniel FriedmanReaders should see WET BASEMENT PREVENTION and also see BASEMENT WATERPROOFING. Readers needing more extensive guidance on preventing or fixing basement leaks and moisture should see BASEMENT LEAKS, INSPECT FOR, or if your building includes areas over crawl spaces, see CRAWL SPACE DRYOUT PROCEDURES. If your building has been flooded, see FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. Our page top drawing of types of indoor foundation and basement drainage systems is provided courtesy of Carson Dunlop Associates.

A perimeter drain, as we explain in this article, is an indoor drain cut into the floor around the perimeter of a basement or crawl space to intercept and remove water from the building interior. We illustrate perimeter drains and we comment on their effectiveness and installation details below.

Interior foundation perimeter drains typically intercept water leaking through a foundation wall or around the building wall/floor slab intersection. The intercepted water is conducted to a sump pit and sump pump for disposal, or it may be conducted to a location from which it can drain by gravity.

Some people call an interior perimeter drain used for basement or crawl space de-watering a "French Drain". Whatever you want to call it, an interior perimeter drainage system cut into the basement or crawl space floor can effectively stop basement or crawl space flooding - or can it?

Wet basement cure: interior drain system (C) Carson Dunlop Associates


In our opinion an interior drainage system can work to keep water off of the floors, and properly installed it can also resist sending problematic high moisture levels into the building as well.

But before installing a costly basement interior drainage system, it makes sense to check and repair obvious outdoor water entry sources that send water through the building foundation walls. That is especially true if the outdoor water entry causes are trivial and inexpensive to cure.

See EXTERIOR WATER SOURCE ELIMINATION and BASEMENT de-WATER vs GUTTERS.

Carson Dunlop Associates' sketch (left) shows three different approaches to installing an interior drainage system to stop basement flooding.

What are the Definitions of a French Drain, Footing Drain, & Perimeter Drain?

French drain sketch (C) Daniel Friedman

 

Well plenty of people do call interior foundation drains or perimeter drains a "french drain". We don't.

A "French Drain" is an outdoor buried drain line constructed to carry water away from the building, typically to a drywell or catch basin. Our sketch shows how we remove water from roof runoff that pours down a downspout.

Details about French Drains are at FRENCH DRAINS


So what is the difference between a french drain, a footing drain, and a perimeter drain. A French drain is shown above, and a footing drain is shown in our two sketches below.

A footing drain, that is an exterior foundation drainage system placed outside the foundation wall near the wall footing, at the level we show, covered with gravel, and if the footing drain going to do anything, it is piped to daylight or to a catch basin that is in turn pumped to daylight or to a storm drain.

Wet basement or leaky basement prevention and cure  (C) Daniel FriedmanFooting drain sketch(C) D Friedman

Details about footing drains - exterior foundation drainage systems - are at FOOTING & FOUNDATION DRAINS

Are Indoor Perimeter Drains a Foolproof Cure for Wet Basements ?

Basement perimeter drain detail, excerpted Journal of Light Construction Dec 2005

Skip the exterior excavation and waterproofing - an interior perimeter drainage system can work just as well, according to Scott Anderson, The Journal of Light Construction, December 2005 [1].

Watch out: our OPINION is that while Mr. Anderson offers good design details for a basement interior perimeter trench and drain system, and though he reports success with this system, we think it's mostly appropriate for an un-finished basement in a home where high moisture from water running down walls is not a concern.

If a basement de-watering design is successful only at keeping water off of the floors, that is if it does not also keep excessive humidity from passing into the basement through walls and floors, the building is still at great risk of high indoor moisture levels, condensation problems, indoor mold, and related troubles.

The basement WaterGuard™ interior basement drain system described in this article shows water running down the basement wall and into the drain system.

Also we notice that the perimeter drain in the example installation is routed to an indoor sump pump that sends water up, out through the basement wall, into a short plastic drain pipe extending about 18" away from the foundation, and thence into an open plastic trench on the ground surface.

If that basement water disposal system is blocked by snow and ice, the sump system will simply stop working and the basement will flood, possibly worse than ever as we have also drilled openings to improve flow of water from the foundation wall into the interior perimeter drain.

Wonderful. And nothing is stopping evaporation of water from the wall surface into the basement area where it causes indoor humidity to skyrocket.

Photos of Basement De-Watering Systems: B-Dri™ and Beaver Basement™ types

Below we show two implementations of the type of basement perimeter drain de-watering system sketched above. At below left you can see that a trench was cut into the floor and something was buried there, along the foundation wall: typically perforated pipe in a gravel-filled trench that slopes around the floor to end at either a sump pump pit or if you are lucky, a spot where you can drain water out of the building to daylight using just gravity.

The installer left a 1/4-inch gap to encourage water that runs down the wall to flow into the drainage trench. This system will usually keep water off of the basement floor quite successfully but it does little to keep moisture out of the area as water evaporates from the wall surface as well as flowing into the trench.

Basement de-watering system (C) Daniel Friedman Basement de-watering system (C) Daniel Friedman

A second common basement de-watering system shown at above-right is also an indoor foundation perimeter drain system like the one we described above. But this installation includes heavy plastic that extends a few inches up the wall, perhaps to encourage water to run behind the plastic and into the gravel trench. This approach also covers up an ugly wet water stained row of concrete blocks at the bottom of the foundation wall. Early B-Dry™ type basement drainage systems used this approach.

At contemporary B-Dry™ and similar installations that we have inspected the installers have shifted to running this heavy plastic barrier up the entire face of the foundation wall, right up to the sill plate. We like that improvement as it should dramatically reduce moisture movement into the room itself as water runs down the wall and into the drainage trench.

In that system one is, of course, unable to see the foundation wall to gain any understanding of just when and where water is entering the structure.

Trenchless Basement Water Interception Systems

Basement de-watering system (C) Daniel Friedman
A "Beaver Basementâ„¢" de-watering system is a simpler basement perimeter catch-and-drain system.

In the installation shown here for a Duluth Minnesota home, the basement dry-out approach uses what looks like a heating baseboard to intercept water passing down or through the foundation wall.

Water runs inside a channel, around the room, and into a drain or sump system. This system, omits the step of cutting open the basement floor to install gravel and drainage piping to the sump.

Depending on the source and quantity of water leaking into the structure, this less costly installation might work.


Basement de-watering system (C) Daniel FriedmanBasement de-watering system (C) Daniel Friedman

Key building water entry diagnosis and cure articles:

  • BASEMENT WATERPROOFING - use of sealers to help keep basements and crawlspaces dry
  • BASEMENT LEAKS, INSPECT FOR - where and how water gets into basements and crawl spaces
  • CRAWL SPACE DRYOUT PROCEDURES - details about curing wet or damp crawl spaces.
  • EFFLORESCENCE, Salts & White / Brown Deposits - these white deposits are a great indicator of where moisture is penetrating a foundation
  • HUMIDITY CONTROL & TARGETS INDOORS - so how dry should a building be for comfort and mold prevention?
  • MOISTURE CONTROL in buildings - master list of detecting and controlling building moisture levels
  • MOISTURE PROBLEMS: CAUSE & CURE - moisture and building energy loss
  • SUMP PUMPS GUIDE - how and where to install a sump pump as an emergency backup against basement or crawl space flooding
  • WATER ENTRY in buildings - causes and cures of un-wanted building leaks in all areas
  • WET BASEMENT PREVENTION - how to stop basement flooding

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.


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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

  • [1] Scott Anderson, The Journal of Light Construction, December 2005 [1]. Mr. Anderson is owner of Tri-State Basement Systems in Berlin VT
  • Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
    Excerpts with updates and annotations expanding the original Best Practices Guide text can be found in the online review and book summary at BEST CONSTRUCTION PRACTICES GUIDE and also at DECK & PORCH CONSTRUCTION, at INDOOR AIR QUALITY IMPROVEMENT GUIDE, and in other articles found at InspectAPedia.com such as HOUSEWRAP AIR & VAPOR BARRIERS, SOUND CONTROL in buildings, and other topics.
  • Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
  • John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net
  • Carson, Dunlop &
Associates Ltd., TorontoCarson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
    • Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
    • Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
    • Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
      Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
    • The Home Reference Book, a reference & inspection report product for building owners & inspectors.
      Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
    • The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones.
      Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
    • The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
      Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
    • The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
  • Home Reference Book - Carson DunlopThe Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

    Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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