Generally, it is not advisable to lay bricks in strong sunlight without implementing significant precautions, as direct sun exposure can severely compromise the quality and durability of your brickwork.
Laying bricks involves creating a strong, lasting bond between the bricks and mortar. This bond relies heavily on the correct moisture balance within the bricks and the proper curing process of the mortar. Strong sunlight disrupts this delicate balance, leading to several potential issues that can weaken the entire structure.
Why Strong Sunlight is Detrimental to Bricklaying
The primary concern when laying bricks in strong sunlight is the rapid drying effect it has on the bricks and the freshly applied mortar.
- Poor Mortar Adhesion: When bricks are exposed to strong sunlight, they can become excessively dry. If a dry brick is laid, it quickly absorbs water from the mortar. This rapid absorption starves the mortar of the water it needs for proper hydration – the chemical process that gives mortar its strength. As a result, the mortar cannot form a strong, lasting bond with the brick, leading to poor adhesion.
- Mortar "Burning": The term "burning" in this context refers to the premature drying and insufficient hydration of the mortar. When mortar dries too quickly, particularly in hot, sunny, or windy conditions, it doesn't get enough time or moisture to achieve its full strength and develop a robust bond. This can leave the mortar crumbly and weak, significantly compromising the structural integrity of the wall.
- Reduced Workability: High temperatures and direct sun can also cause the mortar to stiffen and dry out in the mixing tray or on the trowel much faster than desired, making it difficult to work with and properly position bricks.
While the main issue with strong sunlight is overly dry bricks, it's also important to note that bricks should not be too wet either. If bricks are excessively wet, the mortar will struggle to dry out and adhere properly, leading to a weak bond. The ideal brick condition is slightly damp, allowing the mortar to cure at an optimal rate.
Ideal Conditions for Mortar Curing
For mortar to achieve its maximum strength and adhesion, it requires a controlled curing environment. This typically means:
- Adequate Moisture: Mortar needs water to complete its chemical hydration process. If water is lost too quickly, this process is inhibited.
- Moderate Temperature: Extreme temperatures, both hot and cold, can negatively impact curing. Ideal temperatures usually fall between 40°F and 90°F (4°C and 32°C).
- Protection from Elements: Wind and direct sunlight accelerate drying, while rain can wash away or dilute fresh mortar.
For more information on mortar hydration, refer to resources like the Portland Cement Association.
Strategies for Bricklaying in Hot Weather or Sunlight
When laying bricks in sunny or hot conditions is unavoidable, specific measures must be taken to mitigate the risks:
- Provide Shade: The most effective method is to create shade over your work area. This can be done using tarpaulins, temporary shade structures, or umbrellas. Shading helps keep both the bricks and the mortar cooler and prevents rapid moisture loss.
- Dampen Bricks: Lightly dampen the bricks before laying them. This prevents the dry bricks from absorbing too much water from the mortar too quickly. However, ensure bricks are not soaking wet, as this can also hinder mortar drying.
- Manage Mortar Batches:
- Mix smaller batches of mortar to prevent it from drying out in the mixing tray before it can be used.
- Keep mixed mortar shaded and covered to retain moisture and workability.
- Consider using hot-weather mortar admixtures, if recommended by the manufacturer and applicable to your project, which can slow down the setting time.
- Cure Newly Laid Work: After laying bricks, cover the freshly built wall with tarpaulins or plastic sheeting. This helps to retain moisture and slow down the curing process, allowing the mortar to gain strength properly.
- Time Your Work: Plan to lay bricks during the cooler parts of the day, such as early mornings or late afternoons, especially during peak summer months.
- Monitor Conditions: Pay close attention to temperature, humidity, and wind. High winds, even on moderately warm days, can also accelerate mortar drying.
The table below summarizes the impact of direct sunlight on bricklaying:
| Factor (Strong Sunlight) | Effect on Bricks | Effect on Mortar & Bond | Resulting Issue |
|---|---|---|---|
| Direct Sunlight | Bricks dry out rapidly | Rapid water absorption, premature drying | Poor adhesion, "burning" (weak mortar) |
| High Ambient Temperature | Accelerates evaporation | Reduces mortar workability, hastens setting time | Difficult to lay, compromised bond |
| Wind | Increases evaporation | Causes surface drying of mortar | Cracking, reduced strength, poor aesthetics |
When to Avoid Laying Bricks
It's best to completely avoid bricklaying when:
- Temperatures are extremely high (e.g., above 90°F / 32°C), especially when combined with direct sun and low humidity.
- There are strong winds that can rapidly dry out mortar, even on cooler days.
- You cannot adequately shade the work area or implement the necessary precautions.
For further guidance on best practices, you can often find valuable resources from leading brick manufacturers like Ibstock Brick or local construction associations.
In conclusion, while it is technically possible to lay bricks in the sun, it is strongly advised against doing so without taking diligent preventative measures. Prioritizing proper moisture management and controlled curing conditions is essential for creating durable and stable brickwork.
