Though the levelling properties of screed can provide the perfect solution in a flooring installation, correcting irregularities and providing stability to the floor surface, screeded floors can also go wrong as a result of poor material management.
The negative consequences of screed failure can include:
- Cracking, which indicates poor installation or inadequate drying time
- Discolouration or uneven texture, suggesting that the screed was not mixed properly or applied incorrectly
- A hollow sound when tapping on the surface, signalling that there are voids or air pockets beneath the screed surface, which is often caused by improper compaction during installation or inadequate curing time
It is important to address these signs promptly to prevent any further damage and ensure the longevity of your flooring system. Otherwise, flooring can be costly to repair and replace. Most of all, effective initial preparation is the best plan to prevent these problems from arriving in the first place.
The following provides a list of common mistakes to avoid when installing screed. In each case, it is important to always follow manufacturer guidelines regarding curing times and conditions.
Lack of Subfloor Preparation
Without sufficient attention to detail in preparing a subfloor, issues such as moisture or trapped debris beneath the screed can arise. These imperfections can lead to a weakening of the screed and even can affect the final floor covering. Addressing these underlying issues requires appropriate moisture testing, surface preparation and cleaning.
Additionally, it is vital to plan enough time for screed to adequately dry to prevent resulting problems such as cracking, warping, or reduced strength. It is important to follow the manufactures’ recommendations for the site conditions required, to prevent extensions to the drying process of screed or cracking.
Screeds are not structural, only levelling, and therefore must be applied to a structurally stable floor.
Environmental Factors
One of the critical environmental factors that can cause screed to fail is moisture infiltration. Excessive moisture in the floor can weaken the bond between the screed and the substrate if bonded or affect the surface finish of the screed if water damaged happens after install, leading to delamination and crumbling. This problem is often exacerbated by inadequate damp proofing or lack of site precaution measures, which allows water to seep into the screed.
Temperature fluctuations can undermine the integrity of screed when installed in very hot or cold conditions, leading to cracking or frost damage. This issue can also be a problem in the hardened screed if expansion joints are not installed adequately, again leading to the screed cracking under thermal changes.
Another key factor, exposure to pollutants and chemicals can also compromise the screeds durability. Substances like oil, grease, salts, and acids can corrode or erode the surface of the screed over time, weakening its surface and structure, which reduces its lifespan. Proper maintenance and protective coatings are essential in mitigating these risks and ensuring the long-term performance of screeded surfaces.
Mishandling Materials
Incorrect application technique for screed can have a number of adverse effects. Failing to use proper tools and equipment effectively can cause inaccurate thickness, lack of compaction or uneven distribution of the screed material.
Inadequately mixed materials, such as uneven distribution of aggregates or insufficient blending of binders, can likewise cause weak spots and inconsistencies that can compromise the flooring structure.
Finally, poor quality materials may be responsible for screed failure in construction projects. Using low-grade aggregates or contaminated water can result in a weakened, brittle screed that is prone to more failures. These subpar materials lack the necessary strength and durability to hold up over time.
