Βasements/Foundations Waterproofing:Positive Or Negative Side?(2Nd Part)

A2. DISADVANTAGES OF POSITIVE WATERPROOFING

 1. Positive side waterproofing, being inaccessible, is difficult to inspect and remedy once applied.

You may need to remove tons of earth, destroy vegetation etc.

The whole procedure is highly disruptive and obtrusive.

 2. It's perfectly OK to use positive waterproofing in new constructions but negative waterproofing seems to be the only viable solution for any remedial work.

 3. Positive waterproofing possibly needs an extra concrete slab.

 4. It also may need meticulous and costly waterproofing interventions around many transition details

5. Finally positive waterproofing may need costly dewatering measures.

 B. ADVANTAGES AND DISADVANTAGES OF NEGATIVE SIDE WATERPROOFING

B1. Advantages

 1. The utmost advantage of negative waterproofing is accessibility. Many times this solution is used by default because it is really impossible to proceed to excavations.

 2. In case of waterproofing failure, inspection and remedial measures are much easier.

 3. As well known, cementitious waterproofing is the only way to go. There is an extended know-how and collective experience with cementitious waterproofing systems.

Most technicians are perfectly knowledgeable about them. Their application is relatively easy and when uncracked they can withstand high hydrostatic pressures.

 B2. Disadvantages of negative waterproofing

 1. Most cement based waterproofing products are prone to cracking due to their rigidity. In case of substrate cracking e.g. due to settlement or excessive deflection the cracks will show up on the waterproofing layer.

 2. Negative waterproofing leaves concrete and steel reinforcement easy preys to the corrosive action of water and soil chemicals.

 3. It's difficult - although not impossible - to undertake supportive drainage measures.

 4. Many times costly pre-waterproofing measures have to be taken (please read the relative article on this website).

 5. The use of cementitious products presupposes meticulous and thorough preparatory work on the substrate. The curing procedure should also be impeccable.

 6. Finally the fact that cementitious waterproofing products are water vapor permeable might be a disadvantage in cases such as:

 - delamination problems of floor coverings

- excessive internal relative humidity, inappropriate for the use of the specific space.

 CONCLUSION

 Whenever possible use positive waterproofing.

Negative waterproofing should be limited to those cases when it's nearly impossible to proceed to excavations.

 Chris Strogilis

Civ. Eng. - MBA - DipM

http://maconwaterproofing.blogspot.com