# Waterproofing the basement walls

Waterproofing the walls in the basement is a reverse waterproofing method carried out during repairs or due to construction conditions that do not allow for forward waterproofing to enhance the waterproofing capability for the basement area. Refer to the reverse waterproofing method using the cement-based product SikaTop® Seal 109 VN to find a suitable solution for wall waterproofing in the basement.

Waterproofing construction joints using waterstops is commonly employed in cases of large concrete pours with complex designs to achieve the best results. The method of using Sika® Waterbar V PVC-based waterstop is currently trusted in many projects, with a variety of sizes suitable for various construction joints.  
**Summary of the process  
**Mix the two components of SikaTop® Seal 109 VN using a low-speed electric mixer with a mixing paddle until a homogeneous mixture is obtained.  
Use a trowel and brush to apply 2 layers on the inner surface of the basement.  
After the waterproofing layer dries, use Sika® Latex mixed with the oil and mortar mixture to apply a protective mortar layer over the entire waterproofing surface.

## 1\. Guide to waterproofing basement walls

### 1.1 Product

**SikaTop Seal 109 VN** (15kg/set): a two-component cement-based product, easy to apply, elastic, non-toxic, with good adhesion and water resistance.  
**Sika® Latex** (5L/25L/can): is a liquid additive used for oil-based and mortar mixtures, capable of waterproofing, reducing shrinkage, and increasing elasticity, helping to prevent crack formation.

**\>See more** [**Sika product categories**](https://thehungvn.com/collections/sika)

### 1.2 Necessary tools

Low-speed electric mixer.  
Water spray bottle.  
Fly plaster.  
Brush.

### 1.3 Wall surface requirements in the basement

Apply SikaTop® Seal 109 VN on a solid, clean concrete surface free from grease, dirt, or other easily peelable components. The surface must be as flat as possible.  
Apply the connecting oil-based slurry mixed with Sika® Latex on the fully dried waterproofing layer SikaTop® Seal 109 VN.  
Apply a finishing mortar layer mixed with Sika® Latex onto the wet bonding coat.

## 2\. Construction plan

### 2.1 Impermeabilización con SikaTop® Seal 109 VN  
Mix

Mix the two components of SikaTop® Seal 109 VN together (do not mix with any other substances) in the ratio: water : powder = 1 : 2.  
  
Pour the water component of SikaTop® Seal 109 VN into a clean mixing container, gradually add the powder component, and simultaneously use a low-speed electric mixer with a mixing paddle to mix the mixture evenly for at least 3 minutes until homogeneous.  
  
**Construction  
**  
Ensure the concrete surface is clean, moisten the concrete surface with a spray but do not let water accumulate.  
Use a brush to apply the first coat of SikaTop® Seal 109 VN at a rate of 1 kg/m2, and wait for the first coat to dry for about 4 - 8 hours before applying the second coat.

![Hình ảnh bài viết](https://file.hstatic.net/200000862373/file/z5707197913581_3eb43af0efc6b84ecc5e7582b0b211e8_grande.jpg align="left")

* After the first layer dries, moisten the surface of the first layer with a spray bottle, and apply the next layer with the same rate in a direction perpendicular to the first layer.
    

![Hình ảnh bài viết](https://file.hstatic.net/200000862373/file/z5707197954285_aff3d9c8a795309a0c0fbea6ea8a0038_grande.jpg align="left")

* Always apply a minimum of 2 layers.  
    For large surfaces, appropriate spraying equipment can be used for construction.  
    Cracks or joints between the floor and wall should be roughened before construction.
    

### 2.2 Apply protective mortar with Sika® Latex

Before applying the mortar, brush on a layer of bonding primer mixed with Sika® Latex to enhance adhesion. Mortar mixed with Sika® Latex significantly increases water resistance and reduces cracking.  
Mixing and applying the connecting oil mortar  
Mix the water + latex + cement mixture in the ratio: Water : Latex : Cement = 1 : 1 : 4.

![Hình ảnh bài viết](https://file.hstatic.net/200000862373/file/z5707511151168_7e55f3cfd29cc4a9ce85717cd3867ab9_grande.jpg align="left")

* Use a brush to apply a uniform layer of oil-based primer over the entire waterproofed surface.
    

![Hình ảnh bài viết](https://file.hstatic.net/200000862373/file/z5707498734203_e55bcdee4794eec19679f117af2a8eb3_grande.jpg align="left")

#### Mix and roll the finishing mortar

Mix the mortar with added Latex in the ratio: Latex : water : cement : sand = 1 : 3 : 1 : 3.  
Mix the mixture thoroughly and use a trowel to spread the finishing mortar over the wet oil paint layer.

![Hình ảnh bài viết](https://file.hstatic.net/200000862373/file/z5707224862680_68ffda1074413641877054958938d708_grande.jpg align="left")