Water Damage and Mold

By Robert Robillard on Home Repairs And Remodeling, roof leaks

water damage sub floor rot

Ice Dams, Water Leaks and Mold

Water damage from ice dams, it happens every year, we get calls from clients with active ice dam leaks pouring water into their homes.

What Are Ice Dams?

By know I’m sure your familiar that ice dams occur in regions with deep snow and colder temperatures. Additionally, complex roof structures that trap snow, inadequate insulation, ventilation and air leak sealing all compound this problem.

As snow increases in depth on a roof it becomes an effective insulator – think igloo! Heat escaping from the house warms the underside of the roof and melts the bottom layer of snow and drains down the roof, under the insulating snow cover and freezes once it hits a colder roof surface like an overhang. The ice dam is fed by melting snow above it, the ice dam layer becomes thicker and thicker, creating an ice dam. Dams will only form on roof surfaces that are on the average below 32°F.

Before long the water builds up and creeps back up and under the asphalt shingles, and develops a water leak inside the house.

Water Damage and Mold

Ice Dam Leaks and Water Damage:

Building science experts advocate that we need to view what happens to a house more as a complete system as opposed to symptomatic episodes.   To move forward, after all this winter damage and chaos, we need to start looking a the “house as a system” approach, to diagnose causes and origins of building issues and defects.

Using this house as a system approach we can not only repair the damage but also potentially prevent it from occurring in the future.

In this article I want to focus on repairing the damage with other articles focusing on prevention. Specifically we are going to look at:

  • Insurance claims
  • Water Damage
  • Mold concerns

Water Damage and Mold

 Insurance Claims:

Many folks do not realize they can male a claim for water damage. The question to determine is does it make sense to make the claim or just fix the issue? To make a claim you need to contact your insurance provider and speak with the adjuster, be prepared to provide:

  1. Photos of the damaged area claimed.
  1. A written estimate, from a contractor, for the repairs needed.  Estimates should include a description of the work needed, and a breakdown of the costs by materials and labor.
  1. Materials should be those of the same like, kind and quality of those being repaired.
  1. If contents damage is being claimed, photos of the damaged property should be provided as well.  Provide them with the replacement costs for each item claimed.  A description should be provided and include; make/model, size, material and what the item is.
  1. If you find evidence of mold they will want you to contact them immediately and most likely will assign an adjuster to inspect the site to assist you in moving your claim forward. You will have to look at your homeowners insurance to see if it will cover mold.   Be careful, a mold claim can have a permanent effect on your ability to get insurance later.

Water Damage and Mold

Wet Ceilings, Walls and Floors:

Once the leaking has stopped use airflow from fans to dry out walls, ceilings and floors. Drywall and plaster will dry quickly but hardwood floors may take longer. Solid hardwood floors react to water in three ways, they cup, crown or buckle.

  • Crown: means they raise up in the middle.
  • Cup: means they raise up along the edges
  • Buckle: means the boards come apart and need replacement.

All is not lost when a hardwood floor gets wet, often times it is not clearly evident if the floor is damaged or just pissed off!

I once overflowed my kitchen sink and flooded my kitchen hardwood floor. After vacuuming up the water I ran fans over floor and in the basement over the sub-floor boards.   I was lucky; there was no visible damage. According to my flooring contractor,  it can take anywhere from 3 weeks to 4-5 months for a hardwood floor to settle down after getting wet and crowning or cupping. If there is no staining and the floor settles down your “good to go,” if not, you’ll need to sand and refinish or replace the flooring.Water Damage and Mold

Floor Repair Guidelines

Here’s some guidelines assuming you hire a experienced, quality and licensed contractor, who uses quality materials for replacement:

  • Sand and Refinish:   Plan on spending $2.00 to $3.50 a square foot. The higher range would assume staining to match an existing floor color.
  • Replacement and Finish: Plan on spending p to $10 a square foot for 2-1/4” Red Oak flooring.
  • Removal and Disposal of Old Floor: this all depends on the contractor but a good rule of thumb is to budget $3 a square foot for demo and disposal of the damaged flooring.

Water Damage and Mold

Mold Concerns

A lot of people ask us how long it takes mold to grow after a recent water damage incident; this is the most common question that arises in a persons mind after a leak. First let me just say that I’ve never worked on a house that didn’t have a small amount of mold somewhere – it’s an organism that grows in the environment.

Molds are microorganisms and can be found everywhere. It can grow on almost anything if it is moist enough. Inside your home molds grow quickly on damp surfaces like bathroom walls and trim around windows. Molds may look like furry growth, black stains, or specks of black, white, orange, green, or brown.

In my experience most leaks that are stopped fast enough dry out and do not develop into mold issues. It’s the longer term, constant leaks that you have to be concerned about.   Mold spores needs three things for growth and thrive:

  1. Food (i.e. cotton, leather, drywall, wood, paper products and others).
  2. Water
  3. Optimal temperatures  (temperatures 32 and 120 degrees Fahrenheit. Temperatures from about 70 – 90 degrees are the most conducive for mold growth)

Take away one of these ingredients and it will not grow. The first thing to do is try to limit the “wetting” damage by collecting or catching the water and stopping the leak. Mold doesn’t die when temperatures drop below 32 degrees, they lay dormant until temperatures raise, or they are set out to warm up. de-humidification and good circulation throughout the home is important to eliminate dampness or potential moisture; especially in attics, basements, crawlspaces, laundry rooms.

Post Water Damage Leak:

The next step with water damage is to start the drying process, I always recommend running fans ASAP.   This may also mean having a professional company come in with special fans and carpet cleaning machines.

Most research says that mold will start to grow in the first 24 to 48 hours after a leak, under ideal conditions. As you know carpets get moldy very quick, many older carpets with dirt as a food source start smelling moldy after being wet just a short time.

It may be a week or two before it grows to the extent that it is visible to the naked eye as spots on drywall or carpet pads.

Water Damage and Mold

Rip open the wall?

This is where you have to ask yourself if you need to open the wall to replace insulation or let a cavity dry out.

I had an ice dam leak in my house, prior to installing a new roof a few years back, and was able to stop the leaking within hours of noticing it. I did not open up the wall, and there is no evidence of mold inside or outside this area. That does not mean some mold did not grow in the wall cavity.

Roof Leak and Open Cell Insulation

What if your roof leaks, showing up as stained ceiling plaster,  and you have open cell insulation?  We had this happen to a new construction house, a flashing component was left out by mistake and water got into the roof cavity and wet the open cell insulation. Open Cell insulation is hydrophobic, meaning that it repels or fail to mix with water. In this situation [one-time leak] we first installed the missing flashing and then added de-humidification super close to the leak area for one week.  If the leak had been a longertrm leak, then opening the walls for inspection, and possible mold mitigation, would be recommended.

Proper drying is important

What is most important is how fast and how well the flooded areas are dried. Many times a person will think that moisture was removed when in fact enough moisture was left behind to allow mold to start growing.

How to properly dry out water damage

Proper drying often involves discarding wet carpets and carpet pads because they trap moisture and hamper drying. If the flood was extensive, it may be helpful to remove the baseboards because these baseboards can trap water and prevent proper drying; in more extreme case a few holes can be cut in the walls to allow wet air to escape and dry air to enter the wall cavities.

Use a combination of the following for water damage:

  • Wet vacuums to remove standing water
  • Fans to move air
  • Dehumidifiers to dry the air are helpful, dehumidifiers can dry and maintain air humidity levels between 30% Relative Humidity [RH] and 50% RH it will help everything else in the area dry faster.
  • Consult a specialist in mold remediation, flood damage or carpet drying.

Throw out anything that cannot be cleaned—when molds get inside materials like carpets and mattresses, they cannot be cleaned. Throw them away. But you can get rid of molds in bedding, curtains, drapes and clothes by washing or dry cleaning them. Some non-porous materials can be cleaned.

Water Damage and Mold

Remember the house is a system

According to my Building Science hero, Joseph Lstiburek, Ph.D, P.Eng, there are four steps when responding a mold problem.

  1. Respond quickly with appropriate actions to stop water damage and limit potential exposure to occupants
  1. Identify:
  • The cause of the moisture problem
  • The extent of contamination
  • The safety precautions for remediation
  1. Implement remediation
  • Remove water damaged material that cannot be effectively cleaned or that is more expensive to clean than replace.
  • Clean and salvage materials that are not severely damaged. Dispose of the water damaged material in an appropriate manner. Moldy materials can be sent to a regular landfill.
  • Seal them in plastic bags to protect workers while the material is in transit.
  1. Repair and replace removed materials incorporating the necessary changes to correct the underlying moisture problem.
  • Dry out the area being re-mediated before closing in a wall or ceiling.


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About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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