What is this white fluff growing in my basement?

I live in the countryside of Western Europe by the beach with a temperate climate. After a period of unusual humidity at 84%, I noted this white fluff in the basement floor:

The first picture is about 40 cm and the second 10 cm.

The basement is usually closed and keeps humidity. Temperatures average 18-20ºC, and humidity is now 77%. I assume it's a fungus since the floor was clear before and it seems to collapse when I rub my foot on it.

What is this species, and how can I prevent it?

Update: Following @anongoodnurse's suggestions, it's definitely a salt. I scraped the stuff, poured water, and it shriveled instantly. Here are photos before and after:

Here is a close-up of another piece, where the shards look like a crystal:

It did not smell indeed, and I did not taste it. I opened the basement door to ventilate the area, and I understand that it would accelerate the evaporation of the salty water.

I don't know if this growth has happened before, e.g. because of a leak in a pipe, or is a one-off occurrence, e.g. because of the unusual humidity in the last few weeks. I will check if the basement has any pipes.

Might as well make this an answer.

… it seems to collapse when I rub my foot on it.

As @tyersome stated, it appears to be salt, not mold. Salt crystals would definitely collapse easily underfoot, and should be mostly quite dry, whereas mold would be… maybe squishy (?) but likely unpleasant in some way. Mold also smells, which you haven't mentioned, whereas salt is odorless.

To test, scrape a bit up (salt crystals should feel a bit sandy, not mossy) and see what a drop or two of water does. Mold doesn't dissolve in water; it floats. If water seems to dissolve some of it, add more. If it all dissolves, it's probably a salt, and since you live near the beach, it might be mostly salt, i.e. NaCl, with trace minerals thrown in.

If it dissolves and you're brave, you can taste a tiny bit then spit and rinse. While salt isn't toxic, I can't vouch for what was in the grout.

My guess is that there may be a low spot or two in your basement where salt water is entering through the porous grout; as it evaporates, it leaves salt crystals behind. More water = saltier solution = bigger crystals as the water evaporates.

If you have a magnifying glass, you should see crystals in the undisturbed deposit. If instead it looks soft and hairy, it is mold. I can't think of a white mold off the top of my head (well, Candida albicans, but that smells yeasty and is definitely not crumbly). Mold/yeast needs a substrate (food) to grow on, and wet grout isn't very nutritious. Mildew, sure, but mot big fluffy mold.

I don't like this reference because it's not scientific, but it explains efflorescence well.)

How can I tackle white fluffy growth on wall?

Q I wonder could you give me some guidance about the problem that I have in my front hall. The house is over 100 years old and was totally rebuilt in 1986. The only remaining original wall is at the front of the house. This was dry lined and insulated at the time.

Over the past few years a small fungal growth has started to appear on the wall adjacent to the front door. I have tried to treat it with a variety of paints but to no avail.

A few years ago this section of wall was covered (foolishly) with fireboard and plastered, and now the growth is coming out of the side of the fireboard.

If, as I say, you could give me some guidance or information I would greatly appreciate it. I am assuming the growth is not dangerous to one’s health.

PS: The outside of the wall is rough pebbledash and I wonder if using something like polybond to seal it might help.

A For starters, the white fluffy growth shown in your photograph is not a fungus. It is in fact a bloom of individual grains of salt caused by a process known as salt efflorescence. You can taste them if you wish or dare!

Salt efflorescence occurs when soluble salts, found in some gypsum or cement- based plasters and mortars, dissolve in water to form a saline solution. This solution has the ability to pass through porous materials such as plaster, brick and stone. Once it reaches the surface of the wall, the water in the solution evaporates and the salts recrystallise and form a fluffy growth.

The bloom itself is relatively harmless, causing cosmetic rather than structural damage, and should be brushed away regularly. It isn’t harmful to your health, although I wouldn’t sprinkle it on your chips!

Salt efflorescence is generally caused by damp conditions. In your case, this appears to be localised, with moisture passing into the wall at a joint around the front door. It would be worthwhile to check the seals around the outside of the door – perhaps some caulking or mortar has fallen away and needs renewal and filling. The use of paints to disguise the problem will not provide a lasting solution. Similarly, the use of a product such as polybond will probably only make matters worse by trapping moisture within the old solid front wall.

While the salts aren’t particularly harmful, damp conditions behind the plasterboard may be concealing problems with fungal growth, mould and condensation. If there is a damp musky smell or if black mould is starting to grow on wall and ceiling surfaces, it would be advisable to seek specialist impartial advice from a building surveyor.

If ignored, these conditions could lead to more significant problems with wood rot and deterioration of the plasterboard, while black mould or mildew can he harmful to occupants with respiratory illnesses such as asthma.

Frank Keohane , is a member of the Society of Chartered Surveyors Ireland,

Building dispute

Q My company has employed a building contractor to construct a commercial property which contains an industrial warehouse and a number of offices. We are halfway through the build and the builder is requesting a significantly higher drawdown of funds than usual.

The reason provided is that there were slight changes to the internal design and layout of the offices which is resluting in a significant rise in costs of labour and materials.

We dispute this claim and have reached a point where relations between ourselves and the builder are reaching boiling point.

Can you please suggest an appropriate way forward to break this deadlock so as to reach a fair conclusion?

A It would appear from the manner in which the question is phrased that there is no formal contract in place between the “employer” and the building contractor, or at least that there is no contract administrator on the project advising on contract/cost matters.

The prevailing forms of building contract in this country contain mechanisms for the valuation of extra works (“variations”) and procedures in the event of dispute between both parties to the contract.

It is recommended that a formal contract is always drawn up between the parties to building contracts, based on a clear, unambiguous scope of works, whether that be outlined in drawings and/or specifications or some other form of agreed schedule of the works. It is imperative the consumer is 100 per cent clear on what “he is buying” and the contractor is 100 per cent clear on “what he is selling”.

It appears in this instance that there is not a clear understanding of the content of the contract or how to value changes to the agreed scope of work. Not surprisingly relations between both parties have deteriorated.

It is imperative that both parties move promptly to resolve this impasse as if the dispute is allowed to fester, it could lead to legal disputes and an incomplete building project. In this respect it is encouraging that the writer is seeking to reach a “fair conclusion”.

As the dispute appears to relate to costs as opposed to quality or workmanship issues, we would recommend that a chartered quantity surveyor is engaged to conduct an independent review of the dispute(s) and associated costs.

Ideally the appointment of this person could be agreed by both parties and agreement reached for both parties to share the cost of associated fees.

In the event that this approach is not acceptable to both parties it may be necessary to refer the dispute to mediation or conciliation which are both forms of “alternate dispute resolution” in lieu of reverting to the legal process.

Micheál Mahon is chair of the SCSI quantity surveying professional group

Leasing farm land

Q I am managing the letting of my parents’ agricultural land and am considering renting it out to a tenant on a long lease. How can I be assured that the lease does not grant any rights such as rights of renewal to the tenant?

A Long-term agricultural leases were first encouraged by the Department of Agriculture and Finance in the late 1980s, in place of con-acre/short-term licences, when the Oireachtas reformed the old Land Commission Acts . The main policy objective was to increase land mobility and the productive use of land. Measures to assist the grant of long-term leases were seen as a way to encourage this.

Tax incentives to farm land owners have since been introduced to encourage long-term leasing. There are maximum annual tax-free limits over five to seven years of €18,000, seven to 10 years of €22,500 and over 10 years of €30,000. The benefit from the farm tenant’s perspective includes security of tenure, ensuring their investment in the land can be maximised over a reasonably long term.

When the lease is for land only, no right of renewal will arise, since it does not fall under the definition of a “tenement” as set out in landlord and tenant legislation. In order for the farmer tenant to obtain a new lease, he must prove that the lease qualifies as a tenement and that the use of the premises qualifies as a business. Accordingly, if your farm comprises both buildings and lands, you should ensure that the farmer tenant signs a deed of renunciation of any rights they have to a renewal when signing the new lease. Both parties should obtain independent legal advice in advance of signing any documentation.

A lease is a contract between two parties and it is important for the protection of the landowner and the tenant that it reflects the agreement between the parties on matters such as improvements and capital works such as the erection of structures/buildings, rent reviews, routine maintenance and reinstatement of the land on expiry.

Crucially, the lease should contain a dispute resolution mechanism, particularly as many lettings occur between family members and neighbours. The IFA has developed a master lease which is useful to the parties to identify potential issues that might arise, including how the land will be farmed and managed.

If the landowner dies, the land can be sold with the benefit of the lease. The farmer tenant may also need to consider what should happen in the event of his or her death. The parties may need to consider a break clause allowing them to terminate the lease in the event of death. You should always check the tax position with your accountant in advance of any agreement.

John Dawson is a member of the Society of Chartered Surveyors Ireland

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What is this white fluff growing in my basement? - Biology

Efflorescence is a common problem in concrete and masonry block foundations. The white fuzzy stuff you see along the inside and outside of your basement wall is efflorescence. Don't worry this annoying build up isn't hazardous efflorescence is simply salt and can be easily removed with efflorescence removers and other cleaning techniques. More than anything, if you see efflorescence it means you have a moisture problem and if gone untreated can cause deterioration.

Efflorescence are minerals that are being carried by moisture to the surface and an indication of excess moisture issues.

What happens is, water infiltrates the block or the concrete wall and dissolves minerals. As water evaporates from the surface of the unit the mineral deposits are left behind, thus efflorescence crystals can grow. Although efflorescence is generally a visual problem, if the efflorescence crystals grow inside the surface of the unit, it can cause spalling, which is when the surface peels, pops out or flakes off. The salt pushes from the inside out and can eventually cause crumbling and deterioration.

If the efflorescence is removed, but then returns, it is a sign that water is entering the wall and driving the salts out. If it does not return, then the cause was initial moisture and salts from when the concrete was placed.

Three conditions must exist before efflorescence will occur:

    First: There must be water-soluble salts present somewhere in the wall.

All three conditions must exist. If any one of these conditions is not present, then efflorescence cannot occur.

Preventing Efflorescence

The best way to prevent the problem is to prevent water from infiltrating the wall. If you see efflorescence crystals it usually means there is a leak somewhere letting outside water in. Once, the source of the water infiltration has been located and stopped then the walls can be cleaned with an efflorescence remover.

While inside systems can divert the water, it may not solve the problem of efflorescence and other moisture-related mineral build-ups. Regardless of what is done on the inside, water is still entering through the wall from the outside.

The salt that ends up as efflorescence crystals on your walls, can come from salt laden soils or the Portland cement in the mortar and grout. The soluble salts could come from the sand or from contaminated water used to make the concrete, grout or mortar.

Another culprit is, of course, the clay brick itself. The natural clays used in the manufacture of brick often contain soluble alkali sulfates. Most modern fired clay brick have balanced chemical additives to immobilize the sulfates and render them insoluble. This prevents the salts from being dissolved into a solution that could migrate through the wall to the surface. Most fired clay brick do not greatly contribute towards the efflorescence problem.

How to Clean Efflorescence?

Although not dangerous in terms of health, efflorescence is a warning sign of danger to structural integrity.

The traditional method of cleaning efflorescence has been sandblasting, which, of course, works. Unfortunately it removes just about everything else, too. The abrasive action of the sand erodes the surface of the brick and the tooled mortar joints along with any deposited salts. This increases the porous qualities of the masonry and the water absorptive nature of the wall. Sandblasting should be used with caution and afterwards the masonry should be sealed with a waterproofing material.

An alternative to sandblasting, which has shown good success when done properly is the use of special chemical cleaners. Generally, thorough presoaking and post washing with clean potable water is required. Presoaking is done to saturate the wall, reducing its natural porous tendencies and limiting the depth of penetration of the cleaning solution. After the cleaning solution has been used, the wall must be thoroughly washed with clean water to remove any of the cleaning chemicals. This is very important since most cleaning agents are acidic in nature and cannot be permitted to remain in the wall where they will continue to react with and erode the masonry itself.

A conventional chemical cleaner that has been used for removing efflorescence is muriatic acid in a mild solution, usually one part muriatic acid (hydrochloric acid, HC1) to 12 parts water. Several mild individual applications are better than one overpowering dose. Again, care must be taken to thoroughly presoak the wall with clean water and to thoroughly flush the wall of all remaining acids with clean water.

Remember, cleaning efflorescence from masonry walls does not cure the problem it only removes the symptoms. After cleaning, the efflorescence will reappear unless the natural efflorescent chain is broken.

The presence of efflorescence shows that the salts are already in the wall, have sufficient water to be made soluble, and that migratory paths exist for the salt solution to travel through to the surface.

Efflorescence is a controllable condition that should not be a problem in modern masonry. Breaking the chain of conditions necessary for efflorescence can be done with good details, the correct materials and quality construction.

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If you need a Contractor, we will do the leg work for you. We will find a reputable contractor experienced in the area of work you need help with.

Useful Links
Basement Tip of the Day

Tip #103. Why would it not be enough just to insulate above-grade??

Foundation walls are made out of porous materials such as cement, stone, and cement block, These all consist of porous material, which makes it the ideal situation to wick the groundwater moisture through the porous materials and distribute water vapor throughout the home. This leaching will compete with the ability of the home to transfer heat and cooling, causing higher energy costs.


What are the options when efflorescence rears its ugly head? A fast fix might be to use toluene, xylene or another coat of solvent base acrylic which reemulsifies the original sealer and clears the blush. If vapor continues to come up through the slab though, the condition will most likely reappear. Be aware that if the space is occupied there can be health issues because of solvents like toluene and xylene.

The most prudent course of action includes stripping the sealer in order to conduct a test to determine the rate of vapor transfer and then develop a remedial strategy. It is important to get it right the second time so take time to diagnosis the causes as best you can with the information available. One of the more expensive hand held digital instruments may prove to be a valuable tool because they are able to get accurate moisture reading below the surface of the slab. Once the moisture levels are established a sealer can chosen based upon the manufacturer's recommendations.

Remember that some manufacturers have the vapor inhibiting, non-film forming sealers that we mentioned earlier. These may reduce the vapor transmission rate to a level appropriate for a heavier bodied more abrasion resistant top coat for use in high foot traffic situations.

Where slabs have continued to have efflorescence problems even after the application of a lithium or silicate densifier contractors have used a finish or polish, which are industrial grade "mop and glow" - low build, low solids micronized acrylic water based products as the final treatment. These finishes and polishes can also be used over film forming sealers to add abrasion resistance.

In most efflorescence cases, the decorative flooring contractor inherited the problems that contributed to creating the efflorescence. Diagnosing the causes of efflorescence after the floor has been sealed can be difficult. It is important to determine how much moisture exists in the slab, the source of the moisture and also whether conditions, like seasonal ground water might contribute more moisture in the future. Consider vapor testing and resist the quick fix. Finally, contractors may elect to avoid warranty language where sealers are concerned or they may choose to specifically define typical vapor transmission problems. The decorative adage of "test, test, and test" holds especially true for interior stained floors. It means doing a VTR test whenever you suspect there may be the potential for efflorescence problems. Happy staining and remember – you don't have to take every job that comes your way.

How to Treat White Mold

This fungal disease can be quite difficult to treat, as symptoms of white mold initially mimic many other plant problems. Once white mold is in a garden site, it usually shows up annually, due to the spore’s ability to overwinter in fallen plant debris and soil.

Flowers and damaged plant tissue are often the first to be colonized by the disease. Spores spread not only by wind, but also through insect activity and rain splash. Plant material left behind from the previous year’s harvest is often the culprit of initial contaminants.

There is no approved white mold treatment. Once a plant has the disease, you can try to prune the plant below the infected material and apply a fungicide. However, there is very limited success with this method unless the disease is caught very early. It is best to remove the plant and destroy it.

triumphman on September 01, 2019:

Just found a big infestation on a small tree. I thought it was fungus. Till I took one inside and examined it. It was a catarpiller with feathers White feathery wings all over the leaves. They ate most of the leaves. I sprayed them with a dish soap solution , Eco-oil, and warm water. It seemed make them curl up. I was concerned they would migrate to my deck and eat my vegees in my half 55 barrel planters. Watching closely now ! I need my vegees !

matt on September 10, 2018:

Starting fluid and a lighter work best. They aint fireproof

larry on September 03, 2018:

all my garden problems with powerdy leaves ,bigly came from my evergreen tree took care of cotton bugs thanks

Kenzie on September 23, 2017:

How do you get them away becouse they drive me crazy

Jill on August 19, 2017:

Dang! We call them "Who bugs" ie Horton hears a who. Thought they were precious. not so much now!

Janet Miller on July 20, 2017:

The sticky stuff is not all over my tree its gooie on the leaves and falls like snow from the tree i am worried about my health i have a lung condition copd need info asap. Ty

Jane Mckaig on June 18, 2017:

Thank-you so so much for this info. We thought we were going to have to chop our beloved apple tree down. My husband is out in the garden now blasting away with the hose pipe on full pelt!

Thurman Moore on October 20, 2016:

Thanks. I did spray them with soapy water but did not knock them off the tree. Will do that tomorrow. Too fr to use a hose so will put clear water in my fruit tree spray unit and use it. Very helpful.

country marian on October 03, 2016:

I have a yard full of trees that are covered with these pests. I certainly cannot wash them off with a water hose. For the past two years, I have had this problem but I am afraid to use insecticide for fear of killing birds and bees. The infestation is worse this year and I am afraid it will continue to get worse each year. This is a real problem because this black and sticky residue gets all over our cars, carport, and patio. The sticky leaves and residue gets tracked into the house. Should I break down and use Bayer Advanced Protect and Feed?

Ticia capps on September 29, 2016:

Mine are in a tree over the swimming pool, and cover it. How healthy are they for swimming?

Pinky on September 27, 2016:

I always treated my birch trees in early spring as the leaves appeared to get rid of aphids. Although the extension service will no longer recommend it (back in 1977 they did) I purchased Cygon 2E from the feed store and poured several ounces in a five gallon bucket, stir. Then following the perimeter of the upper tree line which is where your roots are int he ground, pour the watered solution. Results is No aphids for the year. When talking of a 60 ft. tree and aphid sap on vehicles, this was the only solution I found to work. I would not apply near run off to water sources or near edible gardens. Used this for over 23 years with great success. BTW, it also meant I never got aphids on my flowers as well.

How to Prevent Mold From Growing in Soil

Mold can never be totally eliminated. The truth is that mold spores are a regular part of soil and are normally harmless. The real threats to your plant are heat, humidity, and low ventilation. Under these conditions, mold spores grow into their adult fungi form and release even more spores. Indoor planters and container gardens are common hosts, as they retain more moisture. To prevent mold growth, follow the simple steps below:

  1. Don&apost Overwater. Overwatering is the main cause of mold growth in container plants. Soil that is constantly moist is much more likely to harbor happy spores. Water only after a quarter of the pot&aposs total soil volume has dried out. For example, if your plant&aposs soil is 8" deep, don&apost water it until the top 2" have dried out. For most indoor plants, watering once a week should be sufficient.
  2. Reduce Humidity & Increase Ventilation. Together, these two conditions create the stale environment in which mold thrives. By already not overwatering, you&aposre also reducing the humidity, so to reduce moisture even further, place your plants in sunnier, well-ventilated areas or use a small fan to constantly push new air around the soil.

Is It Mold or Perlite?

Don&apost mistake the two: Perlite is a white volcanic glass that is used to improve drainage. It&aposs not harmful to plants.

White Mold in Basement

If you’ve spotted white mold in basement, or any type of basement mold, you may be wondering what it is and what to do about it. Any type of mold, regardless of color, is cause for concern because inhaling the microscopic mold spores can cause health problems, including respiratory problems and allergic reactions. Some types of mold are of more concern than others, though, because they produce harmful substances called mycotoxins that can cause a number of medical problems, some quite serious.

White Mold

Types of White Mold in Basement Environments

Many types of mold can appear white in color, depending on the type of material on which they are growing, including aspergillus, cladosporium, and penicillium (penicillium is often blue or bluish-green and white). Mildew, a type of fungus similar to mold, may also appear white and powdery.


People sometimes confuse efflorescence with white mold. Efflorescence refers to salt deposits found on concrete and masonry surfaces when water has seeped through the concrete, brick, or stone. The water evaporates, leaving behind salt deposits that look a lot like white mold. Unlike mold, however, efflorescence is easy to remove and it doesn’t cause any health problems.


Basement Mold Remediation

If you’ve noticed white mold in basement, it’s important to get it cleaned up as soon as possible to prevent mold-related illness and to prevent mold from spreading to other areas of the home. Many types of white mold spread quickly and easily from one area to another, so if you discover white mold in your basement, you need to inspect your entire home for mold. 

You can purchase mold removal products at most home improvement stores, such as Foster 40-80, that will remove mold from non-porous surfaces like metal and porcelain. It can be difficult to remove mold from semi-porous surfaces like concrete, though, and it’s often impossible to remove mold from porous surfaces like drywall and carpeting. Things like drywall, carpeting, and ceiling tiles usually need to be removed and replaced. Since you often cannot remove and replace moldy concrete, it must be carefully cleaned. Sometimes a sealant is then applied, to prevent any remaining mold from continuing to spread.

For a more details on mold cleaning and encapsulation products, follow the link.

For Help with Basement Mold Removal

If removing mold from your basement sounds like a lot of work, that’s because it is. It must be done carefully in order to avoid spreading mold spores to other areas of the house and to avoid the inhalation of mold spores, which can cause serious health problems as described above. If you’re experiencing any mold-related health issues, or if you suffer from any conditions like asthma or immune system disorders, it’s recommended that you not try to clean up mold yourself because you may end up making your condition worse. The Environmental Protection Agency also recommends hiring a mold removal professional if you have mold covering an area greater than ten square feet or if you have mold in heating and air conditioning ducts.

We recommend scheduling a free consultation with a mold removal professional that will come to your home, inspect the premises, and write out a mold remediation plan including safety protocol. Even if you end up opting to handle the job yourself, you’ll benefit from some free professional advice. Follow the link for a list of mold removal specialists in your area.

I Reduced Humidity but the Fungus Still Comes Back

If you have taken steps to increase the air circulation around your seedling planter and have decreased the humidity around the seed starting soil and the fungus is still growing, you’ll need to take additional steps. Set up a small fan that can blow gently over your indoor seed starting setup. This will help to get the air moving, making it much harder for the fungus to grow.

Be careful though, that you keep the fan at very low levels and only run the fan for a few hours each day. If the fan is running too high, this will damage your seedlings.

Starting seeds indoors doesn’t need to be tricky. Now that you can keep the fungus off your soil, you can grow healthy seedlings for your garden.

Watch the video: Champignons schimmeln Was ist der weiße Flaum? (January 2022).