Waterproof Your Building in Costa Rica – Foundations

Your building and moisture are arch enemies. There is nothing more damaging than water creeping into the gaps and cracks of your building.

It will slowly but steadily deteriorate your building and make you lose your money and happiness with your newly built project.

Now, the bad news: Waterproofing is not taken very seriously by most building professionals in Costa Rica.

Waterproofing your foundations will extend the life time of your building.

If you have visited CR before, you might have noticed already, pretty much EVERY building has some water damage visible on walls or ceilings.

The good news: YOU can avoid the most common mistake with this article. I show you how!

Waterproofing should be an essential part of your building plans, especially if you are building in a tropical country like Costa Rica where it rains A LOT.

Your foundations are the most vulnerable part of your building when it comes to moisture. If they are not correctly waterproofed, water can seep in through cracks and pores and cause serious damage to your building.

Although made of concrete, foundations also need waterproofing due to capillary forces.

Over time, this can lead to the formation of mold, which is dangerous to both your health and the structural integrity of your property. In addition you walls will start to chip off paint and generally look ugly.

Here are my top 4 tips to make sure your building is waterproof: (make sure this is taken care of by your architect or contractor, depending on who is responsible for your project plans & details)

  1. Seal Your Foundations
  2. Purchase Adequate Materials
  3. Keep A Closed System
  4. Don´t get Fooled!

1. Seal Your Foundations

The first and most important step is the get your detail for your building right. Make sure your details define the correct way to seal and waterproof your foundations so no water can seep in. This is critical and often overlooked.

Waterproofing Detail for a Standard Block Wall Construction

Lots of architects are not delivering the correct details to the contractor, for them to implement this properly on site. So make sure you review the details with your architect and if needed get a second opinion from a waterproofing specialist.

The detail i share with you here can be implemented by any contractor, without special know how requried and spending huge amounts of money. There are 4 componenets most important to it:

A. Capillary Break:

Location of Capillary Break

This is a physical break in the continuity of the pores that lets water travel up the wall. In order to avoid this, you need to make sure there is a physical break between the 2 concrete blocks. Use either a bitumen based paint and apply it generously to the top and side faces on the block or because we are building in a earthquake prone area use a special type of conrete additive called “Penetron Admix” which will close the pores of the concrete mixture. This will create a barrier that will stop water from moving up.

Don’t underestimate capillary force. Capillary action explains how water can move up a narrow tube against the force of gravity. It occurs because water molecules are attracted to the sides of the tube. This attraction is called cohesion. The same cohesive forces that allow water to travel up a straw also lets it move through pores in concrete.

B. Drainage Mat:

Location of Drainage Mat
Example of a Drainage Mat

This is a water resistant mat that is placed over the waterproofing membrane. It protects it from any sharp objects that might puncture the membrane and also provides an extra layer of protection against water damage.

C. Waterproofing Membrane:

Location of Waterproofing Membrane
Waterproofing with Bitumen Paint; Bitumen Sheet is still missing.

This is a flexible sheet that is placed over the drainage mat. It is usually made of rubber or PVC and is impermeable to water. This is the most important element of the waterproofing system as it prevents water from seeping through cracks and pores.

Besides green roofs also green facades and living walls are being used more often as they have a lot of the same benefits. They help to regulate temperature, improve air quality and also can create a very nice looking visual effect on the building itself. Check our Beachways Project to see an example.

D. Vapor Retarder:

Location of Vapor Retarder
Example of Vapor Retarder, PE Foil.

This is a layer of material PE foil under your concrete slab in order to prevent moisture from rising up through the slab. The foil comes in sheets so make sure every sheets is carefully glued and sealed to each other. It should be placed on top of a layer of sand to prevent and puncturing of the foil.

E. Drainage

Location of Drainage Piping.

This is a pipe that is placed around the perimeter of the foundation to collect and drain any water. The pipe should be connected to a drainage system that will carry the water away from the building.

2. Purchase Adequate Materials

There are many different waterproofing materials on the market. It is important that you purchase the right materials for your project, based on the advice of a professional. One material might look like the right one but could be completely inappropriate for your project.

For example, one common waterproofing material is called “bitumen”. This is a black, sticky substance that is often used to seal roofs. However, bitumen is not suitable for use on exposed walls because it will eventually degrade in the sun and allow water to seep through.

3. Keep A Closed System

A “closed system” means that there is no way for water to enter the system. This is critical in ensuring that your building is waterproof.

For example, if you are using a membrane to waterproof your foundations, make sure that the membrane is properly sealed at all joints and connections. If not, water will seep in again.

Also, just installing some parts, but saving on some others might cause the whole system to fail. So make sure you do it right, or don’t do it at all.

4. Don’t Get Fooled

Don’t get fooled by your architect or contractor by them telling you that this measures are not necessary. All buildings, no matter how big or small, need to have a proper waterproofing system in place.

Waterproofing your foundations is not something to be taken lightly. It is a critical part of ensuring that your building is safe and protected from water damage.

If you have any questions about waterproofing your foundations, or would like more information, get in touch! I hope this was helpful to you!

Hey There !
To Paradise
& Our Blog

We are Matt & Rhina, the founders of Studio Octava. Studio Octava Is building residential and hospitality projects all over Costa Rica, This blog is about what we’re are working on, what tools we use as well as about our experiences as architects & developers.


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