Seeing is Believing.

Why is This Happening?

The truth is, wood or laminate floors on a

concrete slab at ground level, are not a wise

choice in central and coastal Florida.

On the surface, this probably looks like a self

to this conclusion.

Mike Holmes, the home improvement guru of the

popular TV series, Holmes on Homes isn’t crazy

about the idea either. more on this later.

Here’s why: the photo at right shows one of many

moldy vapor barriers we have removed in the

process of flooring renovation.

It clearly shows mold growth throughout the underside of the vapor barrier. The lower left triangular

area is the concrete slab, showing black mold and remnants of a prior tile installation that employed

roofing felt as an underlayment for ceramic tile; a series of all too common mistakes made by two

consecutive floor installers at this home.

The laminate flooring itself showed no visible signs of mold on it’s surface. It wasn’t detected until

the laminate flooring and vapor barrier were extracted in preparation for porcelain tile installation.

This laminate floor was installed in the early 2000’s. We removed and replaced it with porcelain tile

in the summer of 2009. The home, built in the late 1990’s, is in Suntree.

Another laminate flooring extraction in Titusville shows clear evidence of mold on the surface of the

laminate and on the grey underlayment in the photo below left. Photo below right shows mold within

tongue & groove in the stack of extracted laminate in the background. Foreground shows mold on

ends of laminate that were under baseboard. We extracted this laminate floor in early 2010 and

replaced it with porcelain tile throughout.

In yet another Suntree setting, the slab at the base board area and vapor barrier underlayment indicate

mold. This floor, along with carpet, was removed and replaced with porcelain tile during an entire home

flooring renovation in the summer of 2009. This damage was due to repetitive pet accidents.

We’ve found three primary causes for mold under wood and laminate floors that are installed with a

vapor (moisture) barrier. Unfortunately, wood & laminate floors require a means to block moisture

because they are absorbent materials, prone to warping.

1. Florida has a very high water table and concrete slabs wick water in a capillary action. Concrete

is not a barrier to moisture. If you’ve dug any holes in your yard, you know it doesn’t take long to

hit soggy ground. This is why there are no basements here. It’s just too wet. Concrete slab

construction is an answer to this; however, using the right type of flooring is key.

2. Florida weather can dump more rain in a short period of time than can be quickly drained away.

Think hurricanes and Tropical Storm Fay in 2008. Inevitably, Florida homes are subjected to

potential water leakage and floods. Even short term minor flooding can destroy a wood or laminate

floor. These materials don’t have any resistance to water. Many of the wood floors we’ve removed

and replaced with porcelain tile were damaged by very minor flooding.

The photo at right shows a room affected by the

high water table and lack of proper drainage in the

property’s landscaping.

discovered the large mold patch seen in the central

and back part of the floor.

The dark grey areas indicate moisture in the slab.

A vapor barrier that was beneath the laminate floor

trapped the moisture and prevented it from

evaporating naturally through the home’s air


conditioning system.

3. Pets & normal wear can wreak havoc on wood and laminate floors; warping & mold from pet

accidents; peeling and scratches in surfaces that are not durable enough to take the claws of house

pets and normal wear & tear. Moving furniture across laminate floors often leaves indentations,

scratches and causes peeling at the edges. The balance of wood & laminate we’ve removed and

replaced with tile is due to pet accidents and daily use in active households.

Why is Porcelain Tile a Better Option?

Because wood and laminate flooring absorb moisture, measures to protect these flooring materials must

be taken when they’re installed at ground level on a concrete slab. Vapor, or moisture, barriers can be as

simple as sheet plastic or a more complex multi-ply sheeting that acts as moisture, thermal and sound

barrier in one application.

At first thought, a plastic or vinyl sheet barrier installed on top of the slab under the flooring seems like a

good idea; however, the barriers do not eliminate the moisture in the concrete slab. And, there is a

perpetual source of moisture in the ground under our homes in Florida.

Vapor barriers act much like plastic wrap on top of a steaming bowl of soup. Water condenses on the

underside of the plastic wrap, with no means of escape or evaporation. It is within this environment that

mold has an ideal place to grow, unseen by homeowners.

During construction, many newer homes have another type of vapor barrier installed under the concrete

slab to prevent moisture from accessing the slab. While effective, the success of these vapor barriers

installed under the assembly of the home doesn’t completely solve the problem.

Vapor Barriers

Minor flooding and even regular exposure to rain or pool water at our homes entrances is a frequent

trouble spot. Water drains between the joints, soaks into the body of the laminate or wood and into the

vapor-moisture barrier. Laminates begin to peel, wood warps and the vapor-moisture barrier becomes a

home for mold. The same is true of pet accidents, usually found in corners and along a wall.

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