Raft waterproofing in architecture refers to the process of protecting the raft foundation (also known as a mat foundation) from water ingress, ensuring the durability and longevity of the structure.
This technique is particularly essential in areas with high groundwater levels or where the foundation is exposed to moisture. It involves applying waterproof membranes, coatings, or integral waterproofing admixtures to the reinforced concrete slab to prevent water penetration.
Proper raft waterproofing helps in mitigating issues like dampness, seepage, and structural deterioration, enhancing the overall stability of the building. Effective drainage systems and high-quality materials play a crucial role in ensuring a watertight foundation, reducing maintenance costs, and improving the building’s lifespan.
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Image of Raft waterproofing detail and downloadable (in DWG) link below
Raft waterproofing detail drawing – 1
A raft waterproofing detail drawing typically includes the following elements:
- Raft Slab (Mat Foundation) – The reinforced concrete slab that distributes building loads.
- Waterproofing Membrane – A continuous layer of waterproof material applied below and around the slab to prevent water ingress.
- Protective Screed or Concrete Layer – A protective topping over the membrane to prevent mechanical damage.
- Drainage System – Perimeter drains, weep holes, or a sump pump to manage water accumulation.
- Water Stops – PVC or rubber strips embedded in construction joints to prevent water leakage.
- Filtration Layer (Geotextile Fabric) – A layer to prevent soil clogging in drainage areas.
- Sidewall Protection – Waterproofing on retaining walls or basement walls adjacent to the raft.
- Expansion Joints Treatment – Special sealants or water bars to accommodate structural movement while maintaining waterproofing integrity.
- Blinding Concrete Layer – A thin layer of concrete beneath the waterproofing membrane to provide a smooth and stable base, preventing damage to the membrane.
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