How to Repair Lime Blows in Mortar: A Step-by-Step Guide

Lime blows are a common issue in masonry, especially in historic or older buildings. They are typically caused by the expansion of lime in the mortar, which can create small, round cavities on the surface of the mortar. These unsightly blemishes not only affect the aesthetics of the structure but can also compromise its structural integrity. In this blog post, we will guide you through the process of repairing lime blows step by step. Brick Makeover has an excellent mortar repair service, or you can have a go at DIY!

5 Step Guide to Mortar Lime Blow Repairs

Step 1: Clean the Surface

The first step in repairing lime blows is to prepare the affected area. Use a stiff-bristled brush to clean the surface of the mortar. This will remove any loose or crumbling material, ensuring a solid foundation for the repair.

Step 2: Wet the Area

After cleaning the surface, spray the affected area with water to dampen it. This step is crucial as it helps the new mortar adhere to the old mortar more effectively. The damp surface also prevents the old mortar from absorbing water too quickly, ensuring a stronger bond with the new mortar.

Step 3: Mix the New Mortar

Next, prepare the new mortar mix. It's essential to use a lime-based mortar mix that matches the composition of the existing mortar. Follow the manufacturer's instructions for mixing, and ensure that the proportions are correct. Lime-based mortars are preferred for historical or older structures as they are more compatible with the original materials.

Step 4: Apply the New Mortar

With your new mortar mix ready, it's time to apply it to the damaged area. Use a pointing trowel to work the mortar into the cavities left by the lime blows. Be thorough and make sure the new mortar fills these voids completely. After filling the cavities, smooth the surface to match the surrounding mortar as closely as possible. 

Step 5: Finish the Repair

Allow the newly applied mortar to dry for at least 24 hours, or follow the drying time recommended by the manufacturer. Lime-based mortar can take longer to dry than regular cement-based mortar, so patience is key. Once the repair is completely dry, use the stiff-bristled brush to remove any excess mortar. Clean the surrounding area to ensure a seamless finish.

Important Note:

It's crucial to exercise patience when working with lime-based mortar. Rushing the drying process can lead to issues down the line. Only after the repair has fully dried should you consider painting or applying any other finishes.

Summing up lime blow repairs in mortar…

Repairing lime blows in mortar may seem like a daunting task, but with the right materials and a systematic approach, it can be effectively addressed. By following this step-by-step guide, you can restore the integrity and appearance of your masonry, preserving its historical or architectural significance. Remember that proper care and attention to detail will ensure a long-lasting and visually appealing repair.

One of the great things to remember is that there are plenty of guides out there for DIY. However, it can still seem daunting sometimes to do it yourself. Whether you're worried about the results, or don't have the time, or would simply prefer an expert to complete the work, it's ok. Brick Makeover has an expert team of brick and mortar repair specialists. If you need your mortar repairing you can get a free quote from us today!