Introduction

Poured Concrete Foundation Waterproofing

In both industrial and residential applications, pressurized injection is a preferred repair method for poured concrete widely used across the globe for both the structural repair of concrete and waterstopping. Additionally, pressurized injection is frequently specified as the repair method of choice by Civil Engineers dealing with concrete repair and waterproofing of commercial structures. The widespread use of pressurized injection confirms its use as a highly effective, low cost solution for foundation crack repair, wet basement waterproofing via the elimination of foundation leaks or potential leaks in poured concrete structures. In a residential setting, pressurized injection is almost always less expensive and less invasive as compared to waterproofing methods such as excavation and internal de-watering.

Pressurized injections are widely used around the world and provide a cost effective means of water stopping. In fact, pressurized injection is commonly used to stop underground water leaks in many applications such as:

• Leaky basements and foundation crack repair;

• Rock fissures in mine shafts;

• Leaks in subway tunnels;

• Water ingress and egress in underground concrete structures such as storage tanks, cisterns, foundations, and parking garages;

• Dams;

• Swimming pools in apartment buildings and hotels; and

• Joints between sections of poured concrete sewer pipes.

External Excavation and Waterproofing

In addition to pressurized injection, external excavation and waterproofing is an effective method of waterproofing a poured concrete foundation. External excavation was the traditional way to address basement leaks in poured concrete basements; however, new technologies such as pressurized injection and internal de-watering have gained significantly in popularity in the last 10 years. Below is a list of the pros and cons, as well as other factors, that merit consideration before choosing this repair method for your leaking basement walls:

• The cost of external excavation is significantly higher than both pressurized injection and internal de-watering;

• External excavation will require subsequent landscaping; where applicable, walkways, air conditioning units, decks and pool filters/heaters along the walls of the home in the area of the excavation need to be removed and replaced;

• As with any excavation, there is a risk that hydro and gas lines in the vicinity of the excavation may be cut or damaged;

• The deeper the excavation, the greater the risk of injury or death to waterproofing crews;

• External excavation is a viable repair method when the inside of the home must not be disturbed; for example, when there is a wet bar or built-in bookshelves that cannot be moved;

• An external excavation does not address the mold which has grown behind finished basement walls;

• An external excavation does not reveal the source of a basement leak; this can only be positively established by visually observing signs of water ingress on the inside of the foundation wall;

• The replacement of weeping tile does not guarantee that basement leaks will be prevented. Basement leaks are in fact prevented by the application of a rubber coating or membrane on exterior of the foundation wall;

• During an excavation you have the opportunity to install window well drains;

• During an excavation your weeping tile is replaced. Please note: only companies with a Master Drain Layer on staff are permitted by the municipality to install drains.

Internal De-watering

Internal de-watering is also used for the waterproofing of poured concrete basements. Internal de-watering is used as an alternative to external excavation and waterproofing because it is not as invasive as external excavation; however, the cost can be very similar to the cost of excavation. Below is a list of the pros and cons, as well as other factors, that merit consideration before choosing this repair method for your leaking basement walls:

• The cost of internal de-watering is significantly higher than pressurized injection and can easily be equivalent to the cost of external excavation and waterproofing;

• Internal de-watering does not prevent water from entering your basement. When cracks are involved, the water saturates the concrete surrounding the crack and weakens it;

• Internal de-watering requires the removal of the stud walls along the repair area;

• Proper internal de-watering requires the installation of a sump pump; if this is not installed the collected water will be dispersed beneath the basement floor which is not a recommended practice;

• Internal de-watering does address the mold which has grown behind finished basement walls, since the walls will be removed;