10.1 Waterproofing concept for the parapet
- Selection of membranes
For the single ply waterproofing of parapets, unbacked EVALASTIC® waterproofing membranes or tapes of the required width (girth + min. 10 cm) are used. For full surface bonding you can also use backed EVALASTIC® V waterproofing membranes and self-adhesive EVALASTIC® VSKA tapes.
- The waterproofing of parapets is always carried out “separately” from the waterproofing of the centre area. The waterproofing of the centre area should be raised approx. 5 cm up the parapet.
- Protection against wind uplift: The edge of the waterproofing at the top of the parapet must be sufficiently ensured against wind uplift.
- The installation method and direction of the waterproofing membranes are to be determined depending on the characteristics of the building (height of the parapet, width of parapet top, building material, if necessary perimeter fastening).
- For parapets up to 50 cm height, membranes can be loose laid without fixing on the wall. For parapets over 50 cm height, the membranes must be either fully bonded, or secured intermediately with EVALASTIC® coated metal sheets or single fasteners (max. vertical interval 50 cm ).
The spacing between the individual fasteners must not exceed 30 cm.
10.2 Protection against wind uplift
The edge of the roof waterproofing at the parapet must be sealed so as to be windproof. With loose laid membranes, this is accomplished by mechanically fastened EVALASTIC® coated metal sheet angles 28, whereas fully bonded membranes, depending on the building height and edge details (edge trim, capping), may be additionally mechanically fastened in line.
28 E. g. by underlaying a strip of permanently elastic materials, especially at uneven substrates.
10.3 Edge protection of the roof waterproofing
Inner edges of the parapet must be shaped in such a way that the roof waterproofing can be applied without damage. EVALASTIC® V / VSKA membranes can be applied directly around cut-off edges. Non cut-off, sharp edges can be covered with a mechanically fastened EVALASTIC® coated metal sheet angle.
10.4 Installation with VSKA tapes
EVALASTIC® VSKA tapes are membrane tapes with a polyester fleece backing and a synthetic adhesive compound coating. The coating is bitumen-free and solvent-free and covered with a protective foil when delivered. Until installation, the EVALASTIC® VSKA membranes must be stored in a dark place or covered with tarpaulin. Holes in the lower separation foil must be covered.
Technical data of the coating
|Fastening of coated|
metal sheets in
|with e. g.||spacing [cm]|
|reinforced concrete /|
|• SFS-Spike 4.8 x 25 mm|
• SFS-RNR 6.3 x 25 mm
• body-bound rivet 4.8 / 26 mm
• screws 4.5 - 6 mm with dowel
|lightweight concrete||SFS-IGF-S-8.0 x 65 mm||20|
|steel sheeth||steel blind rivets 4 - 5 mm||10|
|solid wood or chipboard||wood screws 4.5 x 25 mm||20|
EVALASTIC® VSKA tapes are produced with a non-coated approx. 12 cm wide welding edge on both sides (tape width 86 cm / 66 cm), or on one side (tape width 43 cm / 33 cm). Thus, a homogeneous welding of the EVALASTIC® VSKA tapes to the roof sealing and the coated metal sheet angle is guaranteed.
The underside coating of the EVALASTIC® VSKA tapes, in connection with the alwitra primer SK or SK-L (see chapter 220.127.116.11), adheres to all standard building substrates at the roof perimeter or wall flashing area, e. g. timber, concrete, bituminous felt,brick work, zinc and steel sheets, aluminium or synthetic materials. Depending on the substrate, the coating may show at the membrane surface.
EVALASTIC® VSKA tapes can be installed at temperatures over +5 °C. Substrates must have a stable, plain surface, they must be dry and free from grease and oil. A bonding facilitator of alwitra primer SK or SK-L is to be applied onto the substrate (see application instructions in chapter 18.104.22.168). The primer must be completely dry before applying the EVALASTIC® VSKA tapes.
Test bonding is obligatory!
Place the EVALASTIC® VSKA tapes in the correct position. Make sure that the non-coated welding edge is aligned so as to be homogeneously welded to the roof waterproofing after applying the tape. Remove the lower protective foil. Slightly press on the tape to remove any blisters. Then press on thoroughly to ensure reliable adhesive bonding.
Cross joints must be welded over with an unbacked tape. Appropriate measures must be taken to make the upper end of the EVALASTIC® VSKA tapes rainproof.
10.5 Installation of corner waterproofing
The membranes must be laid so as to have as little covering layers lying on top of each other as possible at the parapet corners. Membranes laid parallel to the parapet are butt together at the corner areas or laid around corners. The lap width at the butt joint should be approx. 10 cm.
If corners are formed with EVALASTIC® preformed details, they are to be welded with handheld hot-air guns.
10.5.1 External corners (parapet / upstand – valley area)
- with EVALASTIC® preformed detail
10.5.2 Internal corner (inner top side of the parapet)
- with EVALASTIC® performed detail
10.5.3 Internal corners
- continuous membrane, folded and welded
- with EVALASTIC® preformed detail