Strip Sealants

Solid sealants in tape form are generally semi-cured butyl rubber possessing positive initial adhesion to both surfaces; as with all other sealants used with flashings, they should be used in combination with mechanical fasteners. The cladding thickness determines the space between fasteners to obtain a seal.

For the tape to make positive contact with both surfaces and form a seal, it is important that the tape's initial thickness is greater than the gap between the components of the finished joint.

Soft grades are needed if joints are to be pulled together without bulging of the sheet between fasteners, and some types may be difficult to compress within a joint during cold weather.

All preformed strip sealants require compression by fastening to ensure contact and adhesion to the joint faces.

Sealed side laps for roof and wall cladding must be fastened at maximum centres of 600 mm.

Preformed sealant strip has a release backing paper attached while being applied to avoid placing the sealant under tension that could reduce the tape's cross-section and the elastic memory of the sealant, which can cause shrinkage and discontinuity. The strip should be applied without removal of the backing, with the paper side uppermost and the paper removed immediately before the other component is positioned.
Cellular foam strip produced from EPDM, PVC or other plastics—in a range of sections and densities—require about 25% to 50% compression to achieve a seal.
Installation requirements for solid tapes apply equally to foam strip sealants.
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