Slab Watering And Moisture Management Help Protect Your DFW Home’s Water & Sewer Pipes AND Its Slab From Damage.  Slab bending is when the corners and edges of the slab are higher or lower than the center.  Within this article is a detailed description of Slab Bending — and why it occurs.

Because of Expansive-Clay Soil — All DFW Single-Family Homes Need; Rain Gutters & Slab-Watering To Minimize Slab Bending.  Also (with Lab Testing first) — correct ratios of; Lime, Fly Ash, or Portland Cement can be often be added — to help Stabilize Expansive-Soil (make it react less to moisture changes).  Details are also within this article.

Al’s Plumbing — in Plano, TX provides full-service plumbing; maintenance, repairs, and replacements for every plumbing component in your home.  Al’s sells and installs gas and electric water heaters.  Al’s is near your home in; Plano, TX; Allen, TX; Frisco, TX; and McKinney, Texas.  We service all homes in southern Collin County, TX, and northeastern Dallas County, TX with no additional travel charges.

Call Al’s Today To Discuss Any Concerns Or Problems You Have With Your Home’s Plumbing. 

We will arrange an appointment at your convenience.

Minimize Slab Damage With Slab Watering And Moisture Management

DFW Is Built Upon Expansive-Clay Soil

photo of cracked clay soil

Image Source: Dreamstime

SHOWN: The presence of expansive clays is visible (during dry weather) as soil-cracking.

Note: The Bigger The Cracks — The Higher The Shrink/Swell Potential Of The Soil.

DFW Is Built On Expansive-Clay Soil.  It’s also known as: “high shrink-swell potential”soil.  Expansive-soil is common within the central portion of the U.S.  Expansive soils have fine-grained clay.  When exposed to water — the clay absorbs notable volumes of water and expands.  The amount of expansion is affected by; how much clay & the type of clay.

Expansive-clay soils are prone to increasing/decreasing volume (size) — depending on how much water is currently within the soil.  Over time, structures built on expansive soil are prone to damage from recurring movement — due to the swelling & shrinking of expansive-soils.  Moisture changes in expansive-clay soil cause Slab Bending — which often causes Slab Leaks & slab (foundation) damage.

  • Shrink/Swell Potential of expansive soil is addressed within the International Building Code (IBC) beginning in 2011. (Texas uses the IBC Code).
  • The IBC States:  “In areas with expansive soil — A Building Official shall Require Soil Tests to determine specifically where these soils are located.”


The Risk Of Slab Leaks & Foundation Damage Can Be Substantially Reduced

With Slab Watering & Moisture Management.

  • DFW  homes are built on “Floating Slabs”,
  • This means the slab has the ability to raise & lower with changing soil moisture.
  • What’s important to know is — The Slab Doesn’t Move Evenly. 
  • The center of the slab moves very little (because soil-moisture stays quite consistent).
  • The Outside Edges & Corners move a lot
  • This is known as: “Slab Bending”.
  • When Expansive-Clay soil is wet — it swells in size.
  • This causes the outside edges of the slab to bend Upward — along exterior walls, particularly at corners.
  • When Expansive-Clay soil is dry — it shrinks.
  • This causes the outside edges of the slab to bend Downward — along exterior walls, particularly at corners.
  • This is known as: “Slab Bending”.

Image Source: YouTube Embedded Link

SHOWN: YouTube Video Shows Examples Of Expansive-Soil Damage To A Home’s Foundation

Click On White Arrow To Learn More About Expansive-Soils


Copy The Link Below Into Your Browser To See Core-Sample Of Expansive-Clay Soil When Wet & Dry:

VV  This Section Gives In-Depth Details About Expansive-Clay Soil & Post-Tension Slab Foundations Within DFW.  VV

To Skip This Section — Scroll Down To The Next Double Lines. 

Since 1970, most DFW homes’ foundations are ground-supported, concrete slabs.  Most DFW homes have a Post-Tensioned slab foundation.  A comprehensive understanding of the soil & the bedrock (below the soil) is required to ensure new homes’ slab foundations have the support needed to minimize Slab Bending due to changes in soil moisture.   And, once the house is built — the owner must ensure minimal slab bending with slab watering & moisture management.

Image Source: YouTube Embedded Link

Shown: A Post-Tension Slab Foundation Before Cement Is Poured.

Click On The White Arrow To Learn More About Post-Tension Slabs

What Occurs With Vacant Land In Texas — Before New Homes Are Built On It

When expansive-clays are present — Soil Conditions’ Studies are required by the Texas Chapter of the American Society of Civil Engineers (TASCE).  Starting in 2012 The International Building Code (ICC 2011) added soil testing requirements.  A Study may require soil borings, of up to 20 feet deep, to be taken.  The borings are studied for the presence of expansive clay + estimates of the Soil Shrink/Swell Potential.

NOTE:  Until 2011 — Soil-Borings Were Not Required By The International Building Code (what Code Texas uses).

This is not to say soil-borings were not taken — only that they were not required.


The “Active Zone” of expansive-soil is influenced by seasonal weather changes.  DFW’s Active Zone is typically 10 to 13 feet deep.  Within these depths, soil experiences the most significant moisture changes AND  Shrink/Swell Issues — between DFW’s (cool & wet) Spring & Fall — and our (hot & dry) Summer.  Slab-watering-and-moisture-management reduces shrinking & swelling.

  • Definition: Soil Shrink–Swell Potential is the volume change (change to soil size) — due to moisture-content changes.
  • The higher the Soil’s Shrink-Swell potential — the more foundation damage-risk to structures built on that soil.
  • Low Shrink-Swell Potential = 3%.
  • Medium = 3.1 — 6%.
  • High = 6.1 — 9%
  • Very High = 9.1% +


In 2013, a Soil Shrink-Swell Potential Study was performed on a site located northwest of the Dallas North Tollway & US 380 in Prosper, Texas.  10 feet deep Soil Borings revealed mostly clay soil down to 5-9 feet deep.  To ensure proper support under the slab foundations — the top 3 to 10 feet of existing soil was removed and replaced with soil having a more stable composition.

Conclusions & Recommendations From This Study:

Deep removal of Expansive-Clay soils — to depths of 3 or more feet are often required.

Then, more stable soil replaces the clay soil that was removed.


^^ End Of The Section About Possible Expansive Soils & Post-Tensioned Slabs Ends Here. ^^

Click Here To Learn About How Your DFW Home’s Foundation Is Built: 40+ Slab Leak Signs

AND THEN Scroll Down Until You See:Beginning In The Late 1960s Post Tension Slabs“)

Slab Bending Terms:

  • Doming (slab is lowest along the edges) — during DRY soil.
  • Dishing (slab is highest along the edges) — during WET soil.
  • Changing Soil-Moisture Causes Recurring Slab Bending (up or down) along the outer edges — and particularly at corners.
  • Proper slab watering and moisture management will keep slab bending at a minimum.
  • In DFW, no slab-watering-and-moisture-management — will cause more slab movement than the slab can tolerate (a slab can bend a little).
  • The result is a Damaged Foundation and/or a Slab Leak(s).

Copy This Link Into Your Browser — For A Diagram Of Slab Bending. 

The Diagram Visually Depicts Slab Doming & Dishing (due to changes in soil-moisture along exterior walls).

How Recurring Slab Movement Often:

1. Causes Slab Leaks

2. Damages Slab Foundations 

cracked slab foundation

Image Source: Shutterstock

Shown: Slab Cracked Due To Excessive Movement

How & Why (Water Pipe) Slab Leaks Occur

As you read below you’ll appreciate what a valuable investment slab-watering and moisture management are for the integrity of your home’s slab foundation.

Why recurring slab movement can break rigid water pipes and sewer lines. The horizontal pipes under the slab rise upward through the concrete (and are stuck to it).   When the slab bends, it puts upward or downward pressure on the pipes.

  • The pipes (stuck to the concrete) — and are forced to move up & down with the slab bending.
  • Recurring slab movement creates stress on the pipes. Rigid water and sewer pipes are not designed to bend.
  • The recurring stress can cause rigid water & sewer pipes to crack.
  • Slab watering and moisture-management minimize slab bending.

Click Here To Read Our Article: 40+ Slab Leak Signs: 40+ Slab Leak Signs

The Older Sewer Pipes Become — The More Likely They Are To Crack Due To Recurring Slab Movement.

  • Pure PVC material is brittle.
  • When PVC pipes are manufactured — plasticizers are added to make PVC more flexible.
  • Over time, these plasticizers leach out — and PVC sewer pipes become more brittle.
  • Cast-Iron sewer pipes rust from the inside toward the outside.
  • As they get older — they’ve become thinner due to rusting.
  • This makes them more subject to cracks.

Minimize Slab Bending With Slab Watering And Moisture Management

Slab Bending Refers To:

  • The sides & corners of the slab move Downward due to dry soil.
  • The sides & corners of the slab move Upward due to wet soil.
  • Note: Soil-Moisture is increasingly stable going toward the center of the slab.


  • Slabs are designed to bend a little.
  • Slabs are not designed to bend as much as Expansive Clay Soil swells and skinks.
  • Recurring slab bending often cracks the slab at the origination-point(s) of the bending.

On A Side Note…

Adding Proper Ratios Of Materials May Help Stabilize Expansive-Clay Soil.

This YouTube Video Demonstrates Soil Shrink-Swell Testing.   

Image Source: YouTube Embedded Video Link

SHOWN: Soil Shrink-Swell Testing

Lab testing is the most accurate way of determining clay soil’s shrink-swell potential.   With that information — the lab should be able to advise the proper ratios of the materials shown below.


  • Do a Google search to find a Soil-Testing Lab near you.
  • Ask the Lab if they can give you proper ratios — upon having tested soil from your lawn.

Note: Al’s Plumbing does not provide soil testing.

  • Calcium/Lime

Adding calcium to expansive clay soil treatment is an effective way to stabilize it.  Adding lime (calcium oxide) changes the mineral makeup of clay — and reduces the shrink-swell potential.

Often the most effective treatment is; lime & fly-ash mixed with water.   You need a Lab Test Professional to advise of the proper ratios for your lawn. 

  • Fly Ash

Fly ash by itself can reduce potential shrinking and swelling — and help rid soil of moisture that’s trapped inside.

It’s often an excellent choice if your soil is subjected to large amounts of water.

  • Portland Cement

Portland Cement helps to stabilize expansive clay soil by increasing its dry-density.


How To Minimize Slab Bending / Movement

1. Install Rain Gutters — To Route Rain Water Away From The Foundation.

2.  Establish A Recurring Slab-Watering Program During DFW; Spring; Summer, & Fall.

NOTE: We Provide In-Depth Details About How To Establish A Slab Watering Program Later Within This Article.


1. Install Gutters — To Route Rain Water Away From The Edges Of The Foundation.

  • Allowing rainwater to fall along the edge of the foundation — creates dramatic changes in soil moisture.
  • Rain Gutters catch and divert water away from the foundation.

brick home

Image Source: Shutterstock

Shown: This Home Shows Rain Gutters Installed.   There’s a gutter downspout (the white vertical pipe) — left of the garage door.

It’s Equally Important To Install Rain Gutters’ Downspout-Extensions

To Carry Rain Water 3–6 Feet Away From The House.

 Image Source: Embedded Shopping Link

SHOWN: Slip-On Gutter Downspout Extension.

Click On Image To; View Product, Read Details, or Purchase From


  • The downspout shown Extends Up To 6 Feet. 
  • The 6-foot extender is located under the 3 foot piece (as shown).  Simply slide the lower extender as needed. 
  • The downspout shown Flips Up.  This makes lawn mowing easier.  
  • This style simply slips around the bottom of the downspout. 

Downspout Extension Installation

  • First, remove the existing “L” shaped bottom. 
  • Slip the extender onto the (vertical) downspout. 
  • Note:  These are often larger than the downspout.  Even when they fit — they tend to slip off (if not secured). 
  • To Secure: Drive 1 or 2 screws through the (sides of the) extender and into the downspout.   
  • An aluminum downspout accepts screws with little effort. 

2. Establish A Recurring Slab-Watering Program

During DFW; Spring; Summer, & Fall  

  • If You Have An In-Ground Water-Sprinkling System — It Can Be Adapted To Water The Foundation Too (or it may have been installed with this feature).
  • Contact your system’s installer about modifying your in-ground sprinkling system.


No Automatic Lawn-Watering System?  No Problem.

The Items Below Can Create An Above-Ground, Foundation-Watering System


Image Source: YouTube Embedded Video

Shown Above: Flat-Style Soaker Hose Actively Watering  (it’s round during use).   


Image Source: Embedded Shopping Link

SHOWN: Flat-Style Soaker Hose.

Click On Image To; View Product, Read Details, or Purchase From

  • Soaker hoses create “beads” of water — resulting in slow and controlled watering.  This allows for more precise watering amounts.
  • With correct water pressure (by adjusting the flow at the faucet) — soaker hoses won’t add water faster than the soil can accept it, resulting in no wasted water.


  • Flat-Style Soaker Hoses (versus the stiff & round style) — are much easier to work with. 
  • The round ones are more trouble to place and must be uncoiled first. 
  • Flat-Style soaker hoses eliminate these issues. 
  • AND — Flat-Style are much less expensive. 


  • You can connect an additional 25-foot soaker hose on the end of the 1st (25-foot) one.
  • It’s advised not to extend beyond 2 hoses — as watering quantity reduces further down the line.
  • If you need more than 2 soaker hoses — run a separate garden hose to the soaker hose(s) that are farther away.


  • Place soaker hoses 18 inches from the edge of the foundation — they will overwater if placed closer.
  • If you have Mulch planting beds — you can bury the soaker hoses inside the mulch.  This will reduce evaporation and required watering frequency.
  • This is not recommended for planting beds with rock.  Rock is too heavy for a flat soaker hose to open correctly.  Also, the rocks may puncture the fabric hose.

Automate Slab Watering — With TIMERS That Attach To Outdoor Faucets

 Image Source: Embedded Shopping Link

SHOWN: 4-Outlet Battery-Operated Timer

Click On Image To; View Product, Read Details, or Purchase From


  • Timers screw directly onto an outdoor faucet (you can see the gold screw-on fitting at the top of the timer shown).
  • Timers are available in 1, 2, 3, & 4 Outlet(s) versions.

NOTE: Put something under the timer if it’s horizontal once installed (like with a faucet that comes up from the ground).  The weight of the timer + hoses can crack the plastic on the water inlet (what screws onto the faucet).

NOTE: Water only 1 Zone at a time (underground systems do this).  There isn’t enough municipal water pressure to water multiple zones at once.

TIP:  Water at night to minimize evaporation.  Check with your City, but most allow foundation-watering at any time and on any day.

  • Hoses screw directly onto the Timer’s Outlets.  The hose filter-screens (at the lower right corner of the timer shown above) — typically come with the timer.
  • The timer must be programmed (by you) — to set which day(s), which zones, and how many hours you want each Zone to water (each outlet serves 1 zone).
  • Watering time will change with increasing outdoor temperature and hours of sunlight.

TIP: It’s easier to program the timer before it’s screwed onto the faucet.

NOTE:  The length of time must be increased/decreased based on the time of year.

TIP:  You can also automate lawn sprinkling with the same timer.

TIP: If You Don’t Want To See The Timer & Hoses Connected To It

Image Source: Amazon Embedded Link

Shown: Plastic Decorative Rock

Click On Image To; See Product, Read Details or Purchase From

The product shown above comes in 3 sizes and 2 colors (beige or gray).

If you have a faucet, that comes up from the ground — you can cover it (and the connected hoses) from view.  The product shown above comes in 3 sizes and 2 colors (beige or gray).  Adding fiberglass insulation at the top of the rock will further protect the faucet from freezing.

TIP: Put the fiberglass insulation inside a trash can bag to eliminate exposure to it.

TIP: At the end of the watering season — disconnect the timer from the faucet.  Under this rock — you can simply leave the timer & hoses as they are.

TIP: This also eliminates damage from the sun.

These rocks don’t seem to degrade much over the years (from sunlight exposure).  An owner states they look the same 7 years later.

How To Know When You Are Watering Enough?

  • The amount of watering needed — must be adjusted for higher outdoor temperatures and longer daylight hours.
  • To accommodate this — simply extend/reduce watering time.
  • To know if you are watering only as much as needed — Install Moisture Meters.

Soil Moisture Meter

 Image Source: Embedded Shopping Link

SHOWN: A Simple & Easy To Read Moisture Meter.

RED = Dry / GREEN = Moist / BLUE = Wet

Click On Image To; View Product, Read Details, or Purchase From


  • Select a location midway between the starting and ending ends of the hose(s).
  • Simply push the rod into the ground.
  • The rod needs to go deep to be accurate.  Push into the ground until very little of the rod is showing.

TIP: There’s only so much water pressure — so limit soaker hose(s) to no more than 50 feet.  The longer the hose — the less water it drips further down the line.                    

              Other Important Things To Know

  • Most (if not all) municipalities allow foundation-watering at any time and on any day.
  • Check your City’s website to ensure you are in compliance – if foundation-watering restrictions apply.
  • Place soaker-hoses 18 inches away from the foundation.
  • The best time to water is at night.  There’s no sun and cooler temps — this reduces evaporation.
  • Begin with the water-timer set for 2 hours (per zone), per week.
  • Monitor soil moisture to determine if 2 hours is enough.  Adjust as needed.



This Article Details Slab (foundation) Watering & Moisture Management needed for every DFW home.  These steps minimize slab foundation bending/movement and the damages that slab bending cause.

Al’s Plumbing — in Plano, TX provides full-service plumbing; maintenance, repairs, and replacements for every plumbing component in your home.  Al’s sells and installs gas and electric water heaters.  Al’s is near your home in; Plano, TX; Allen, TX; Frisco, TX; and McKinney, Texas.  We service all homes in southern Collin County, TX, and northeastern Dallas County, TX with no additional travel charges.

Call Al’s Today To Discuss Any Concerns Or Problems You Have With Your Home’s Plumbing. 

We will arrange an appointment at your convenience.