Wood floor shadows

OK, I don’t normally get too involved in diagnosing why something is the way it is but rather just report what I see. In this case, I’m a little mystified and really want to help my 1st time home buyers understand what it is they are getting. The attached photos are from a 1960-ish, slab on grade, one story home. There were no obvious indicators of a slab problem nor obvious roof leaks or anything like that. The, what appear to be, original wood floors were stained in several rooms for no apparent reason. In a couple of areas the stains look like where something was placed and turned the wood dark under it. In other areas the dark stains did not have well defined edges and appeared more like what you’d expect from moisture from above or below. I did take a couple of moisture readings in the dark areas (in the 3rd & 4th photos) and they do indicate a 4-7% more moisture content than the light colored areas of the floor. The blue and red walls were outside walls but nothing outside helped explain, no sprinkler system, slab > 8" above grade, etc. Let’s speculate what might be causing this.

The dark areas are most likely moisture related. Hard to tell in photos.

Source may be pet or they didn’t wipe up spills, clear coat is delaminating grain pops causing loss of the finish adhesion, and what appears to be White Oak tannins are drawn toward the outside as drying occurs causing the darker stained areas.

  1. This may be hard to swallow but the rectangle looks like a leaky cat box that has completely removed the finish or a heat source, seen this before. Almost appears to be the footprint of a steamer trunk with the brass bumpers at the corners.

  2. Looks like a Thigh Master imprint or one of those ergonomic backless chairs

  3. Looks like lazy finish, in painters terms “Holiday”, incomplete sanding and previous finish color, but again the finish is delaminating, which leads us back to moisture.

  4. Can you say “Wee-Wee-Wee all the way inside the home”, unless another source can be identified.

This is why it is important to photograph occupied homes, never know what under or behind the pretty furnishings.


I agree water another thought could be leaking fish tank but Cat,
dog or plants .
Roy cooke sr

If the last two pictures are of exterior walls, you may have a situation of air infiltration through the bottom of the exterior walls. Air movement may bring in moisture along with it.

Also, if the landscaping on the exterior of the house is being watered consistently, the edge of the slab may be absorbing some of the water and bringing it up to the top of the slab.

You notice it more often when there’s carpeting in the room. That telltale dark band around the exterior wall perimeter is dust trapped in the carpets. The carpets act as a filter.

3 and 4 definitely look like cat pee to me. Have had way too much experience trying to remove cat pee stains. Even sanding doesn’t completely remove them. As soon as the new finish is applied, they reappear. Cat pee stains are usually found under rugs or wall to wall carpet when removed to find the hardwood floor.

#1 looks like heat damage from a space heater. Been there, done that. Learned my lesson. Replacement is not cheap.

#2 looks like puppy pee. Been there, done that one, too. Now when I get a dog, I get one that’s already full-grown, like from the SPCA’s kennel.

#3 and #4 look like moisture stains from poor/deteriorated/uninsulated wall/floor junctions.

Thanks guys, I think I’ll just e-mail this thread directly to my clients and let them see 1st hand what everyone thinks.

Poor sanding job leaving gouges and areas of more open grain that took stain differently?

Phot 1 appears to be that of a small freezer or something that a condensate line or tub leaked from.You can see where water or some form of liquid ran to the wall due to elevation sloped toward the wall.The one that has two legs ,looks like a dog came by and peed on whatever was there on a regular basis,and the previous owner just wipe around the area instead of moving it.