Alex Burman, Product Manager for Waterproofing at Sika Limited explains…..
Towards the end of last year Sika launched SikaProof® P as an extension of the SikaProof® system of below ground waterproofing membranes. SikaProof® P is a post-applied version of SikaProof® A made from the same core material so that the interface is fully compatible, using the same accessories.
Here is a quick recap of SikaProof® A – The ‘Pre-Applied’ System – to outline how it works and where the post applied system fits in.
SikaProof® A – Pre Applied System
This membrane is installed in the formwork or on blinding before the reinforcement and concrete is placed. The Flexible Polyolefin (FPO) material is, as it states, very flexible and easy to use. The flexibility allows it to be formed around construction features without the risk if splitting, and ensures a tight fit around penetrations, such as pipes.
When the concrete is cast onto the membrane, the fibres in the fleece are drawn into the concrete forming a continuous bonded system. Behind the fleece, the unique sealant grid prevents the lateral movement of water, in case of any damage to the membrane.
SikaProof® A is available in 1m and 2m wide rolls with prefabricated self-adhesive strips down the length. Fewer joints and faster installation time, makes the whole process more efficient, especially on large areas. The ends of the roll, and any details, are simply bonded with self-adhesive tapes, which ensure fast and secure installation.
SikaProof® A is best used for under basement slabs and on vertical wall sections – using either single or twin-wall formwork.
SikaProof® P – The Post Applied System
SikaProof® P is installed on the existing concrete or other suitable structure. It is ‘peel and stick’, which means that the self-adhesive membrane system is installed by peel and sticking directly onto the hardened concrete surface – just like wallpaper. The surface bond is created and enhanced by the system primer (SikaProof® Primer-01) to ensure a durable adhesion of the unique Sika® adhesive sealant within the membrane system onto the existing concrete structure.
Because SikaProof® P is made from the same material as SikaProof® A, the two materials can simply be overlapped to form a strong and durable bond. No other material is required at the interface. This means that the post-applied system can be used under the base slab and on walls where it is easier to do so, and the post-applied system can be used for all other situations.
Better Toe Details
For example, as typical construction method is to have a “toe” detail where the ground slab extends beyond the wall on top. It is difficult to pre-apply a waterproofing membrane on the top section of this toe detail, because the concrete cannot compact underneath it.
In the past contractors would use an alternative material, such as a bitumen sheet or liquid, to complete this area, connecting from the pre-applied membrane on the end of the slab, to the pre-applied membrane on the wall. This is not ideal, as you may have issues with compatibility and performance between the two.
SikaProof® P can now be used to complete these toe details and you can be sure that the system will be compatible and durable. In addition, the simple application means that you could post-apply the waterproofing membrane to the wall sections as well.
Another area where SikaProof® P can simplify installation is where tiebar holes are required when constructing using twin-wall formwork. Tiebar that hold the formwork together will leave holes in a pre-applied membrane, which have to be patched up once the formwork has been removed.
Instead of a pre-applied membrane, SikaProof® P can be post-applied to the concrete wall after the formwork has been removed and tiebar holes sealed, covering them without any patching required.
SikaProof® P extends and completes the SikaProof® system, by adding a post-applied membrane that works directly with SikaProof® A. Giving a greater choice for contractors when planning and installing below ground waterproofing systems.
For more information please visit www.sikawaterproofing.co.uk