Reddish brown wall growth not mold (C) Daniel Friedman Brown Mineral Efflorescence
Salt Deposits, Brown Bubbly Walls & Plaster - Diagnostic Photographs

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Moisture & dark efflorescence, stains, or "growths" on building surfaces:

Red or Brown Building Stains & Deposits that are not mold:.

Here we illustrate and explain the cause & cure of reddish brown or pale yellow bubbly surfaces on walls, especially masonry walls or on masonry chimneys, caused by leaks & moisture - efflorescence and sometimes creosote leaks.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

What is the Brown or Reddish Bubbly Stuff Found on Building Walls?

Effloresence (C) Daniel Friedman

When investigating a building for a mold problem, you can save mold test costs by learning how to recognize Stuff that is Not Mold or is only Harmless Mold but may be mistaken for more serious contamination - save your money.

Our photo at page top shows white fluffy crystals of mineral efflorescence near the bottom of a poured concrete foundation wall.

Because some clients have on occasion sent samples to our lab that really should not have been collected, much less looked-at, I provide this library of photographs of things that are "not mold" and don't need to be tested.

These are substances that you can easily learn to recognize in buildings.

Save your mold test money, and increase the accuracy of your mold contamination inspection or test for toxic or allergenic mold in buildings: review these items to learn recognize non-fungal materials or even possibly harmless cosmetic "black mold" often mistaken for "toxic fungal growth."

These photos of ugly reddish brown and white bubbly "growth" on a plastered masonry wall were sent to us by a reader.

Reddish brown wall growth not mold (C) Daniel Friedman

This stuff looks like terrible mold but it's probably not mold at all. We won't know for sure without testing the material or inspecting the building.

But it sure looks like reddish-brown salts left behind by water and moisture passing through a masonry wall or a plaster wall, evaporating from the wall surface and leaving behind all of the crud that the moisture picked up from the wall itself as it passed through.

We often find this darker colored wall deposit on older buildings built of brick and stone whose interior wall surface is plaster applied directly to the masonry wall. We also often find this wall "growth" when water has been leaking in a plaster wall cavity.

Plaster is so alkaline that it is not as friendly to mold growth - it's not "mold proof" as mold may grow on or in paint or even on or in organic material in or on the plaster.

More red stains found indoors are discussed at STAINS on INDOOR SURFACES, PHOTO GUIDE

What is Causing the Bubbling and Peeling of Paint on Foundation Walls?

Mineral salts and water pushing off paint (C) Daniel Friedman Mineral salts and water pushing off paint (C) Daniel Friedman

Take a look at this closeup (above left) of peeling paint on a foundation wall in a basement. The lumpiness of the surface tells us that this wall has been painted a number of times, painting over a rough concrete or concrete block surface.

In the center of the photograph (above left) you can see where paint is falling away and the gray concrete or concrete block is exposed. At the upper left corner especially you can see rounded bubbles of material that looks as if it is "growing" on this foundation wall.

Effloresence on masonry wall (C) DF S

The author's hand (photo above right) shows a combination of peeling paint, deteriorated masonry surface, and mineral salts all left behind as water and moisture have been passing through the building foundation. There is a water problem in this building and a moisture problem, but the stuff on the wall and in hand is not mold.

These pictures shows combination of peeling paint and yellowish-white mineral salts left behind as water is passing through this wall as moisture or as actual liquid water.

The moisture is both pushing paint off of the surface and also leaving behind salts of various minerals that were dissolved out of the wall as the moisture passed through it. When water evaporates from a surface it leaves behind minerals that were dissolved in it.

In our photo at above left we see bubbling paint and plaster on an interior wall surface - an indication of the "lift" power of the mineral crystalline salts formed as efflorescence under a paint layer.

Diagnosis of White & Brown Stains on Brick or Concrete Block Chimneys

Chimney stains - white (C) Daniel Friedman Chimney stains - brown (C) Daniel Friedman

White powdery stuff appearing on a brick chimney may show up indoors or outside (photo above left). Brown stains leaking out of any chimney (photo above right), whether masonry or metal, may indicate a dangerous condition - prompt inspection is needed.

We find these stains on concrete block or "cinder block" chimneys as well, and occasionally on stone chimneys.

Brown stains on a chimney wall may also show up indoors or outside (photo above right). The brown stains are probably from creosote or soot washing out of the chimney interior flue and leaking into the attic through the chimney wall. This chimney needs immediate inspection and repair.

In either case we recommend that you promptly hire a professional chimney sweep to inspect the condition of the chimney including at the rooftop and inside the chimney flue. Water leaks into a masonry chimney can damage it and make it unsafe both structurally and with respect to leaking dangerous flue gases or even sparks that could cause a fire.


Diagnose, Remove, Prevent Brown & Gray Efflorescence & Growths on a Concrete Slab Floor

Gray & brown fluffy growth on a  basement slab: mold or effloresence following sewage backup and wet conditions (C)  ASQuestion: what is this gray, brown, and white fluffy stuff on our basement slab?

Our home was built in 1915, and probably hooked up to the combined sewer that was in place after 1906. Their mistake, in hindsight.

We have a sewerage district that has wisely begun uncoupling those old connections where separation was not required.

Walked down to the basement today and found a bunch of these little deposits. They’re moist spots, with maybe some efflorescence, but a gray, dusty/powdery layer over it. All over, various sizes/density. Have not noticed them until now.

[Click to enlarge any image]

I can’t tell if this is:

1) Basement crud (lint, fur, dust) collecting on moist spots

2) Moisture that is seeping up and generating mold, on top of efflorescence

3) some other gross accumulation

I don’t notice a smell at all, so I would rule out animals.

I opened the basement heat vent a few weeks ago, which I think was a mistake. The dehumidifier shows 40-45 humidity, and has all winter. That humidity and the temp seems way too low to generate/support mold growth. - Anonymous by private email 20 March 2018

Gray & brown fluffy growth on a  basement slab: mold or effloresence following sewage backup and wet conditions (C)  ASReply: probably efflorescence; focus on sewage backup cleanup & sanitizing

The photos are a bit blurry and of course a lab analysis is a much more accurate answer to your question, but what I see looks to me like efflorescence with possibly some green mold growth.

Mold does not much like raw concrete, but mold of many species will grow on organic debris that might be on concrete, more so if it's enriched by sewage or sewage effluent. That means there could be bacterial hazards as well.

It would make sense to clean and sanitize the surface, then give some attention to

1. inspection of the sewer line to be sure it's intact

2. steps to dry out the area - see WATER ENTRY in BUILDINGS - home - as a reasonable place to choose among diagnosis and remedial steps

Reader Follow-up:

I learned a lot by spending some time on the site last night. I'll do some clean up and dry out this weekend and see what happens.

We are looking at disconnecting/capping the downspouts that feed into the foundation drain from the roof, as well as a French drain in the back where a slope comes down to the house from the rear of the lot (high point).

Gray & brown fluffy growth on a  basement slab: mold or effloresence following sewage backup and wet conditions (C)  ASAt some point, we will need to re-cover or repair and level the floor. I'd like to find a better (and more cost-effective) management for this issue in the meantime.

There was a known sewer backup through the floor drain from a combined sewer a few years ago, and there are water marks around the columns, but the dark spots here are moisture welling up through the floor (which is painted green).Sorry the images were so large, I attached a smaller one with a bit better resolution.

Thanks for what you do, this kind of information and advice is so helpful.

Reply: why mold can grow on concrete

Your message reminds us of the difficulty of guess-diagnosis of building conditions from afar. In virtually 100% of the cases in which I haven't visited the property I have found important data that significantly amended or improved our diagnosis over what we might first have seen by email.

For example it's a classic mistake to connect downspouts conducting roof drainage injury foundation drain system. That overloads the foundation drain or the life of the building on the foundation drain system becomes clock with those conditions send significant amounts of water under the foundation under the slab.

Heading to the previous sewer backup means we've added nutrients that would invite both balding bacterial growth. I think you're quite right start outside getting roof runoff well away from the building. And you want to clean sanitize the slab.

Looking again at your photos I think there could be fungal growth along with of course other substances, though the first best guess remains efflorescence You could probably confirm efflorescence by shining a bright light obliquely along the substance to look for shiny crystalline structures that will be more obvious under a hand magnifier.

There are as well mold species that will grow on almost anything, but on concrete where I find mold (such as an old concrete basement floor) usually the mold is growing on some organic deposits: possibly in this case sewage remnants?

A cleanup that addresses a sewage backup would probably be fine for removing the mold too; I'd follow any sanitization or disinfection by a careful inspection to be sure we're doing all we can to keep the area dry

. Aside from the water entry in buildings link I gave before, if you haven't done so, see the steps at BUILDING DRY-OUT PROCEDURES


What Does it Mean to Find Efflorescence and Stains in a Building Interior?

Leaky wall and effloresence (C) Daniel Friedman

MOLD & HEALTH WARNING: although efflorescence is not mold, it often indicates wet conditions that cause problem mold growth elsewhere in the same building.

You'll need to identify the sources of moisture or leaks and correct them, and depending on other building air quality complaints or health concerns it may be appropriate to inspect and screen the building for problem mold or other moisture or water-related problems.

Where you find efflorescence in a building indoors, you should look for problem mold, allergens, bacteria. Look on organic surfaces - wood, paper, painted surfaces, insulation, fabrics, carpets, carpet padding, or in settled dust and debris.

In our photograph (above left) the client is pointing out that water has been entering this basement from the very top of the foundation wall (due to outside roof spillage and bad drainage) - we did not agree with the contractor who told her this was "rising damp" due to wet soils.

Remove & Prevent Efflorescence on Building Surfaces & Materials

This discussion has moved to EFFLORESENCE REMOVAL & PREVENTION


Continue reading at EFFLORESCENCE SALTS & WHITE DEPOSITS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.





Or see this

Article Series Contents

Suggested citation for this web page

EFFLORESENCE & BROWN DEPOSITS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

HTML Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher - Daniel Friedman