Ask the BuilderAsk the Builder
Ask the Builder's on:

Subscribe to askthebuilder's videos

Air Conditioning
Asphalt - Blacktop
Brick
Building Tips
Cabinets
Caulk
Ceilings
Ceramic Tile
Checklists
Chimneys
Concrete
Concrete Defects
Concrete Installation
Condensation
Countertops
Deck Construction
Deck Maintenance
Design
DIY
Doors
Drainage
Drywall - Plaster
DVDs
EBooks - EDocs
Electrical
Energy Savings
Engineered Wood
Fences
Fireplaces
Flooring
Foundation
Garage Doors
Glue
Hardware
Heating Design
Home Builders
Home Depot Stories
House Plans
Hurricanes
Insects
Inspections
Insulation
Interior Walls
Kitchen
Lighting
Lots
Miscellaneous
Mold
New Construction
Newsletters
Online Courses
Outdoor Projects
Painting - Staining
Patio
Payments
Plumbing Design
Plumbing Supplies
Projects
Radiant Barrier
Remodeling
Retaining Walls
Roofing
Rough Lumber
Screened Porches
Sheds
Siding
Specialty Accessories
Stone
Storage
Structural
Stucco - EIFS
Tools
Trim Lumber
Vapor Barrier
Ventilation
Videos
Walk Throughs
Wallpaper
Windows
Glossary






Flooded Basement and Hurricane Winds

By Tim Carter
©1993-2008 Tim Carter
Summary: Masonry walls made from stone, concrete block, brick or a combination of the materials can look fine, but wind-driven rain can really cause waterproofing problems. Massive amounts of water can enter through invisible passageways.

DEAR TIM: My finished basement was flooded by rains produced as hurricane Frances lumbered across North Carolina. I have a concrete block foundation that has a stone facing above grade. What is the best way to waterproof both the visible and buried parts of my foundation? What kind of drainage system in the yard can I install to help deal with the massive amounts of water that fell from the sky and then into and across the land? Paige H. Black Mountain, NC

DEAR PAIGE: I am sorry to hear about your misfortune. You are not alone in your suffering as I heard from no less than 100 homeowners and builders who have suffered water leakage into brick veneer and concrete block buildings and into basements such as yours.

The hand-pump sprayer is doing a fine job of saturating the stone foundation. If you use the right product, it can block all sorts of gaps where water can enter. Photo Credit: Tim Carter
There are a series of factors that may be responsible for your basement flooding. It can indeed be your masonry walls, but it can also be roof gutters and downspouts that are undersized, clogged or empty on the ground next to the house. The soil around your home could have flat or even negative slope so that water pools against your foundation. To add insult to injury, your original builder may have never truly waterproofed your foundation.

The hurricane or tropical storm winds that pounded your home are powerful. Rain that pelts against houses, with even a mild breeze during a rainstorm, can create leaks in walls that seem to be impervious to water. Each drop of rain water is like a hammer as it strikes the wall surface. It pushes the previous drop of water into the wall. Imagine thousands or even tens of thousands of drops of water combined with the actual wind pressure of a tropical storm or hurricane driving the water deeper and deeper into the walls.

Perhaps the most common entry point of water into a masonry structure is through the vertical mortar joints in brick, concrete block and stone. Even though you can't see cracks where this mortar touches up against the masonry units, water, and lots of it, can and does penetrate here. If your builder did not create a system for this water to be collected and redirected to the exterior, I can see why you had the leaks.

Once your walls dry out, you can seal them very effectively with a two-step process of water-based products. The first step is the application of a clear penetrating silane - siloxane water repellent that coats the entire masonry wall. Two coats must be applied and they must be applied within 30 minutes of each other. If you wait too long between coats, the first coat of the water repellent actually starts to work and stops the second coat from entering the masonry units and the mortar.

Immediately after the water repellent is applied you can then brush on a masonry joint sealer - very interesting milky product that has the consistency of canned gravy before it is heated. Once applied in a thin coat over the mortar joints and a portion of the brick, block or stone next to the mortar, it dries clear. This amazing product, when applied correctly, can bridge cracks up to 1/8th inch!

The water that falls onto your roof and the land around your home must be captured and diverted to the lowest spot on your lot. Often I hear about rainfall amounts of four, five or even eight inches of rain from one of these storms.

For sake of discussion, let's say 4.5 inches of rain fell at your house during the storm. If your roof area and combined yard area is say one-half acre, the rainfall dropping onto your property was 61,096 gallons of water give or take a drop or two! If your lot receives water from an uphill neighbor, then even more water was possibly charging towards your basement.

I feel it is imperative to capture all roof water with gutters and downspouts. The water from the roof should enter an underground piping system that directs this water to the lowest part of your property. Be sure your local codes allow this. Some municipalities require storm water to be piped to a special storm water system that retains it and slowly releases it over time to the natural streams and rivers in your area.

You should also install an underground gutter system in your yard that captures any subsurface as well as surface water that is passing through and on top of the soil. You can dig a 6-inch wide trench that is 18 to 24 inches deep. Install a perforated drain tile in this trench and fill the trench to the top with washed rounded gravel.

Once the pipe passes the house and is headed towards the lowest part of the lot, make sure the pipe is level in the trench. Since most building lots have some slope to them, the pipe will eventually extend to daylight and be visible. Water will gush from this pipe during and immediately after a heavy sustained rainfall.

The next time you are a passenger in a car being driven through a moderate rain storm, open the window and let your hand get hit with some of the rain drops. You will be shocked how hard they hit your hand even while driving 30 miles per hour. The force at 70 miles per hour is almost painful.

This type of energy can easily defeat walls that have not been perfectly waterproofed. The new masonry sealing systems are effective, water-based and can last for up to ten years between applications. An even better characteristic is that they are very do-it-yourself friendly.






Comments

mike malley
09 Jan 2008, 18:42
Hi, Had 55-60 mph winds this am. Wind is blowing through our cellar and putting out our oil heater. I need to learn the proper way to seal up the stone basement. I am retired military, navy of course, meaning that I know very little about home repairs. Also I have esrd, kidney disease, so I am not all that strong. Every time I hire someone I seem to get screwed. I would like some info on the proper way to seal the walls in my basement. Thank you very much. Mike
AsktheBuilder
09 Jan 2008, 18:56
Mike,
Go read all of my past columns about tuckpointing. You might be able to do this as it is not too strenuous. Thanks so much for your service to our great nation.
Tina
08 Aug 2008, 18:07
Can you tell me if weep holes are required as a code on brick and stone construction in Tennessee. What happens if a home of that material was built without weep holes. Also this home has a basement and the inspector said that it smelled musky in the basement. The home is not and has not been lived in for quite some time and he said the musk smell could be because of it being closed up. Please contact me asap with any advice and Tn.or national building code information

     View all comments
*Name:
Email:
Notify me about new comments on this page
Hide my email
*Text:
Security Image:

Visual CAPTCHA


 







Ask the Builder Comment Help

Helpful Comment Tips: If you need help with a problem, please try these things now before you type in a comment. You could discover your answer in just minutes.
  • Read ALL Comments Before Submitting One: If there are lots of comments that are already part of this column, there is a very good chance your question has already been answered by me or someone else.
  • Read Similar-Titled Columns First: The column above is almost always part of a two-or-three-part series. The answer to a question you may have is probably in a related column or in comments that are part of that column.
  • Read Columns in a Category: Take the time to read many columns in a category. The amount of information you will discover will amaze you.
  • SHARE a Story: Please share any tips or amusing tales of glory! Tell others what has worked for you. Maybe you have a disaster you want to discuss. Let's collaborate so we all learn together.
Don't show this alert again.