They’re called “efflorescence.” The presence of efflorescence in the middle of these dark blotches is a sign that there is probably water moving through slab.
Why is there a wet spot on my basement floor?
If you begin to notice wet spots on the basement floors or walls, you probably have a basement moisture problem. Persistent condensation can lead to structural damage. In many cases, a dehumidifier can provide a solution. Another common contributor to a wet basement is runoff from gutters.
Why does concrete have dark spots?
If water has a high iron or mineral content, or if the water is carrying leaves or dirt, it can leave behind iron or rust colored stains, or dark spots on the concrete.
How do you get rid of damp on a concrete floor?
When faced with damp in concrete floors, there are two options available:
- Dig up the old concrete floor, install a new damp proof membrane and lap up edges before replacing the concrete slab.
- Fully isolate the dampness in the floor using a surface Damp Proof Membrane (DPM)
How can you tell if a concrete floor is damp?
Concrete Moisture Test
One of the simplest, most economical test methods for determining whether there may be moisture in concrete is the ASTM D 4263 Concrete Moisture Test. Duct tape an 18-inch square piece of plastic onto the exposed concrete and leave it for 16 hours.
Can moisture seep up through concrete?
Humidity—warm and humid air condenses into surface moisture when it comes into contact with the cool surface of your concrete floor or slab. Faulty/Missing Vapor Barrier—moisture from the ground can seep up and through the concrete.
Can water seep through concrete basement floor?
YES, water around your foundation can come up through the concrete floor and can leave any material on its way soggy and damaged.
What is concrete mottling?
Mottled concrete is irregular shapes of different shades of white- gray to gray-black. These blotches are restricted to the surface, normally only 1/32″ to 1/8″ deep. They can diminish over time but usually are permanent. The concrete is almost always sound and meets specification.
How do you remove black algae from concrete?
A Pressure Washer Is the Best Concrete Stain Remover
The best way to remove mold, moss, and algae is to kill the roots or uproot the colony, and while scrubbing with soap and water is the safest, most reliable method, a power washer is faster.
How do you check for moisture under flooring?
Pinless meters can rapidly test for moisture in floors without leaving pin holes at the testing site. Simply press the meter’s plate flat against the floor, take a reading, and repeat the process at different spots until you find the moisture pocket.
Why is my concrete floor always wet?
The most common is old fashioned condensation, otherwise known as sweating. The issue could also be caused by poorly installed concrete (moisture below the slab).
Does concrete floor need to breathe?
There is no need for concrete to breath from the point of view of the strength of the material. There will be moisture retained from the original mix and it is possible some are confused about the chemistry of concrete and think it needs to dry, but the truth is the complete opposite of that.
Can you tile over damp concrete floor?
It is never a good idea to install tiles over concrete that is suffering from a water issue. The concrete slab must be remediated prior to laying down a new floor. This is in order to assure a strong bond with adhesives that will be used in the installation.
Will tiling stop damp?
Short Answer: Yes, you can tile a damp basement if it’s rising damp, but it’s very important to use breathable tiles, such as unsealed quarry tiles or natural stone tiles that have been treated with a water-based sealer, such as LTP Mattstone H2O.
Should a concrete floor be sealed before tiling?
We’ve done the searching for you and have some excellent information. Sealing a concrete floor before covering it with tile or carpet is a great idea. Sealing the concrete can prevent condensation and protect the floor. This means your carpet or tile stays dry and thus lowers the chances of mold and mildew building up.
Is there a sealer for concrete?
There are two main types of concrete sealers: film-forming sealers and penetrating sealers. Film-forming sealers include acrylics, epoxies, and urethanes that form a coating on the surface of the concrete. Film-forming sealers, especially acrylics, are more susceptible to wear and will need to be reapplied frequently.
Should I seal my basement floor?
Whether you plan on finishing your basement space or keeping it in its original state, it is important to apply a waterproof sealant to the concrete floor in order to lock out moisture. An epoxy-coated basement floor is one of the best ways to maintain and preserve your space.
What is the best way to seal a concrete basement floor?
When sealing basement floors and foundation walls the best concrete sealers to use are the Lithi-Tek 4500 primer followed by the Siloxa-Tek 8510 waterproofing sealer. If you are going to be installing flooring in the basement, it is best to use a moisture vapor barrier coating like the Vapor-Tek 440.
