The installation of upstand strips around shower trays and baths is now common practice. Gerry Robinson, Technical Manager of Sealux, looks at the state of art and explores relevant issues tile and bathroom retailers might consider before choosing which solution they endorse.
Upstand strips most often take the form of a 70/120mm wide impermeable sealing strip with a pre-applied high tack adhesive bed on one side that allows bonding the strip onto a shower tray or bath side wall before final installation against walls. That part of the upstand sealing strip that extends above the ledge after installation is subsequently sandwiched between the shower wall and tile. Upstand sealing strips are promoted as secondary perimeter joint seals that guard against leaks resulting from sealant failure in the tile/ledge joint.
Codes of Practice
There are no Codes of Practice regulating the design or quality of shower tray and bath upstand strips. In the absence of a British Standard, two distinct sealing strip versions have emerged in the market that serve to highlight a ‘disconnect’ between what plumbers install and what tilers require. This disconnect relates to material compatibility.
The EPDM upstand sealing strips supplied by plumbing merchants have a low surface energy that limits adhesion with sealants, tile adhesives and waterproofing membranes. The equivalent fleece faced sealing strips favoured by tile adhesive manufacturers accommodate good mechanical adhesion with these materials.
BS5385 Part 4
Because upstand sealing strips are installed during installation of shower trays and baths, it is generally the plumber who purchases and installs them. Consequentially, EPDM sealing strips have gained good traction in the market. Unfortunately, the installation of an EPDM sealing strip is not conducive to the subsequent waterproofing of shower walls.
This anomaly between the EPDM sealing strips promoted by the plumb sector and the fleeced PE/PP sealing strips favoured by tile sector is destined to remain unless rectified in BS 5385 Part 4 (currently under revision) which deals with the issue of waterproofing shower walls and the sealing of movement joints in wet and damp conditions. A recommendation in respect of integrating upstand strips into adjacent shower wall waterproofing membranes might align practices in the plumb sector with best practices in the tile sector.
Now that upstand strips are here to stay, tile and bathroom retailers promoting shower waterproofing materials might also take a lead and specify that where upstand strips are installed, they must accommodate good adhesion with adhesive sealants, tile adhesives and waterproofing materials in the knowledge that every such upstand strip installed is not just good preparation for waterproofing shower walls, but also advantageous in eliminating the task of connecting the waterproofing membrane onto the shower tray or bath ledge.
The ‘stick-on’ sealing strip concept
Unlike the plumb sector where the installation of ‘stick-on’ EPDM sealing strips is standard practice, fleece faced sealing strips have been comparatively slower to catch on in the tile sector where complimentary shower waterproofing and tanking solutions are a staple diet of many product ranges.
The reason for this may be that there are inherent flaws associated with the basic butyl adhesive ‘stick-on’ sealing strip design:
Butyl adhesive can react with sealant. Sealant applied into a tile/ledge joint can react with the adjacent butyl adhesive changing it from a high tack adhesive to a viscous stringy soft cream that can ooze out from behind the sealant onto the ledge.
Stick-on upstand sealing strips can create perimeter ‘canals’ over the butyl adhesive upper face between the ledge and upstand strip. This ponding effect feeds capillary action up the shower walls.
Upstand sealing strips bonded across the rounded side wall corners of shower trays and baths do not readily extend into the adjacent 90° wall corners causing tile deflection.
Upstand sealing strips are installed by plumbers. Full responsibility for the waterproofing of tiled wet areas should rest with one installer – the tiler.
These and other problems are inherent because they cannot be disassociated from the basic ‘stick-on’ upstand sealing strip design. To eliminate these problems a paradigm shift in the product design and installation practice is required.
A Paradigm Shift in Upstand Strip Technology
As a designer and manufacturer of movement joint seals committed to improving the state of art, Sealux have developed an upstand sealing system called HydroHALT that eliminates all the afore mentioned problems associated with ‘stick-on’ butyl adhesive upstand sealing strips.
The HydroHALT design sets aside the use of butyl adhesive and the associated ‘stick-on’ installation method in favour of a more innovative solution that is superior in material composition, offers greater installation versatility and higher product performance.
HydroHALT combines a revolutionary upstand strip (not a sealing strip) with a sealant and backer cord. The HydroHALT Sealing System complies with relevant best practices promoted in BS5385 and BS6213 in respect of:
- the designing of movement joints to relieve built up stress
- joint substrate preparation for sealant compatibility
- joint substrate preparation for sealant adhesion
- the proper selection and dimensional application of sealant
- use of backer material to accommodate sealant flexibility
HydroHALT eliminates the material compatibility problems and installation limitations associated with butyl adhesive stick-on upstand sealing strips. Other advantages of HydroHALT are:
can be installed by:
a) Plumbers – during installation of new trays and baths
b) Tilers – into existing joints around new trays and baths
c) Tilers – over tray and bath ledges in refurb projects
d) Tilers – over trays and baths with integral up-stands
e) Tilers – around low profile shower trays as low as 6mm
- extends 100% into 90° wall corners – no tile deflection
- eliminates ponding under tiles – no capillary action
- meets relevant BS5385 and BS6213 Codes of Practice
- compatible with liquid and mat tanking system