Alumasc answers their most frequently asked questions about the Hydrotech hot melt system

Q1. Can Hydrotech 6125 Monolithic Membrane be installed to Plywood?

There are no issues with the installation onto a Plywood substrate. As part of the preparation works it will be necessary to tape substrate joints with approx. 100 to 150mm wide strip of Flex Flash F laid centrally, bedded into a thin skim coat of Hydrotech Monolithic Membrane 6125 prior to main works.

Q2. What are the differences between the Hydrogard Protection Sheets used as part of the Hydrotech 6125 system?

Hydrogard 20 Protection Sheet is categorised as the standard grade product for use within an inverted roof assembly. It is a polyester reinforced, oxidised bituminous protection sheet, with a sanded finish to the upper side. Not suitable for application where exposed to Ultraviolet (UV) light.
Hydrogard 30 Protection Sheet is a more robust product suitable for use where the imposed loads are expected to be much higher. It is a glass/polyester reinforced SBS modified bitumen membrane, with a black mineral surfaced upper side.
Hydrogard 40 Protection Sheet is a heavy duty product incorporating a root resistant additive making it suitable for use within a green roof assembly. It is a polyester reinforced, APP modified bitumen, root resistant membrane, with a charcoal mineral upper surface.
Hydrogard 50 Protection Sheet is an extra heavy duty product principally engineered to meet the specific requirements and stresses for civil engineering works. It is a dual glass/polyester reinforced APP modified bitumen membrane, with a smooth black finished upper surface.

Q3. Can EPDM overlap Hydrotech 6125 Monolithic Membrane?

The use of EPDM flashings typically as part of a façade or cladding assembly which are required to overlap the Hydrotech 6125 waterproofing is common and a widely acceptable detail. The critical factor is ensuring that the EPDM product and its method of application will not have any adverse effect on a bituminous membrane i.e. by using a non-solvent based bitumen compatible adhesive. In the first instance the supplier of the EPDM should be asked to confirm in writing that the product will not have any adverse effect on the primary waterproofing system, which can then be further evaluated for compatibility by Alumasc technical services following receipt of appropriate product data sheets etc.

The effectiveness and bond strength of the product to the Hydrotech 6125 waterproofing is the responsibility of the adhesive product supplier to establish (by test if necessary) and confirm. As with any third party supplied products, it must be noted that should the product have any adverse effect on the Alumasc waterproofing at any time, any costs for any remedial work found to be necessary would not be covered by the Alumasc warranty.

For further information about Alumasc’s Hydotech 6125 click here or contact our technical team on 03335 771 500

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