Water is an integral part of concrete mixture and if you are making a floor out of concrete, it is quite apparent that water will be used as a binding agent. Many problems occur due to high moisture content, such as dampness, mold and mildew. In some cases, floor installations also come off with the passage of time and weaken the flooring of the house. If we look around our house, garages and basements have a typical concrete floor and these rooms usually do not have enough ventilation, which keeps the moisture retained, increasing the probability of floor damage. This blog will share some simple tips to prevent moisture in a concrete floor and also highlight the underlying factors, causes and sources of moisture in the house’s flooring.
Causes of Moisture in a Concrete Floor
The moisture that retains in a concrete floor usually finds its way to the middle layer. Between the ground and the concrete slab, there is a sub floor, which can accumulate water resulting in problems in the flooring.
There are various causes of moisture in a concrete floor – some are quite apparent like wet building sites – while others are hidden and indistinct like insufficient sub-slab moisture protection, change in the quality of materials and ineffective moisture tests.
If we talk about ineffective moisture tests, there are two ways it can go wrong. Only the in situ RH test measures any moisture below the surface of the slab. If you choose any other test besides the one mentioned above, then it will only give you the floor’s surface picture, which will be inaccurate. Another common error homeowners make while testing the floor’s moisture is to keep less sensors throughout the floor’s surface, which will not give you the correct picture.
In some cases, the contractor or a homeowner wants the house to be built quickly. However, concrete slabs need time to set in properly. A power trowel machine is often used on slabs to speed up the flooring process. Due to compression during the troweling process, the porous nature of concrete gets affected, closing all evaporation outlets, which retains extra moisture and needs more time in drying.
Let us now discuss some of the most common sources of moisture in concrete flooring before we discuss the ways to prevent it.
Common Sources of Moisture in Concrete Floors
The main source of moisture in a concrete floor is the proportion of water mixed with cement. If it is a lot more than you think, then it affects the functionality of the concrete floor. There are other external sources of water present on the construction site that you should worry about, which can affect slab drying and curing.
Following are the main sources of moisture in concrete floors.
- Rain and sprinkler systems present on the construction site indiscreetly penetrate the tiles and grout, allowing mildew to grow on these spots, which causes the adhesive to deteriorate
- The groundwater present below the surface also has a huge impact on the moisture conditions of the concrete slab
- If there is any poor plumbing system, it can cause a leak which results in water infiltration
- Condensation on a slab is another factor to cause moisture in a concrete floor. It occurs because of low air’s dew point which means the air can no longer retain any moisture, Therefore condensation occurs on the slab which then absorbs the water content
- Moisture has the tendency to level out itself. For instance, if the air’s relative humidity (RH) is more than that of the concrete slab, the moisture will move to the concrete
- Inadequate drainage around the concrete slab increases the risk of having high moisture content in the sub layers of flooring
Tips to Prevent Moisture in a Concrete Floor
Here are some easy yet effective tips in keeping moisture out of the concrete floor.
- It is important to strike a balance between the water to cement ratio. The more water there is in the mix, the greater time it will take for the concrete to set in. Don’t add water in the concrete mixture that is already mixed. If the water content is too high, it makes it difficult to manage timelines.
- If the construction site is wet, you must install more drainage lines and use pumps to dewater the site. Displacing water is an effective way of keeping any source of moisture away from the concrete floor
- The layers of the floor can retain moisture due to water seepage. Use a vapor retarder with a perm rating that shows how much
- The layers above and below the concrete slab are areas where water seepage can affect the floor’s functionality. Use a vapor retarder or a barrier that will not allow moisture to escape through the layers. A retarder can effectively keep under-slab moisture from moving through the flooring system. Use a certain thickness of sand and lay down a highly durable plastic such as a thick polyethylene sheet, then use another layer of sand above the plastic sheet. After that, you can easily construct the concrete floor. For wood flooring or wooden tiles, use a proper underlayment that can effectively stop the moisture penetrating the floor. It is important to install a plywood underlayment that can add extra protection. It should also be tested to ensure that it doesn’t bring in any moisture
- You must give the concrete slab some time to cure and dry out itself. If it is a fast-paced construction project, the time to allow the concrete to set in is more. Make sure you give ample time and space for the concrete to set itself
- Keep below grade excavations free of water to prevent reservoirs of moisture from moving upward through the slabs. Excessive moisture present in concrete slabs can cause structural degradation of the soil
- A liquid epoxy damp proof membrane should be applied once the slab is constructed. It creates an impermeable layer. It not only provides a good surface finish to the floor, but it can also be applied without the need for drying it. Remember to clean the concrete surface with a brush and apply the damping agent. Apply multiple layers of the damping agent and allow each layer to set first.
We hope this comprehensive guide on preventing excessive moisture in concrete floors will help you keep the floor in top shape. If you are installing carpet over the concrete base, then take a look at this detailed blog: Carpet Installation Guide. Homeowners who choose tiles must go through this article on different floor tiles in Pakistan and their rates. Don’t forget to write to us at email@example.com and we will surely get back to you. Subscribe to the Zameen Newsletter appearing on the right hand side of the page.