SILCOR® 575 LB is GCP's one-part, semi self-levelling, high-solids polyurethane waterproofing membrane for horizontal substrates set to falls. It forms a Class III high-extensibility membrane for internal wet areas and external horizontal waterproofing.
The semi self-levelling formulation is designed for horizontal work and produces a smooth continuous membrane. Compared with the non-sag 560 HB family, 575 LB is the better fit where the membrane needs to flow out across a horizontal substrate set to the required drainage falls.
GCP allows 575 LB in exposed horizontal areas when it is overcoated with SILCOR Top Coat 75 as the UV colour-stable, foot-trafficable protective finish. 575 LB is not suitable for heavy-duty foot or vehicle traffic, even with a protective top coat. For those applications, compare SILCOR 580.
Adheseal currently lists SILCOR Top Coat 80, but GCP's current 575 LB system specifically calls for Top Coat 75 for exposed 575 LB. Do not substitute Top Coat 80 unless a current GCP project specification explicitly permits it.
For prepared substrates below 5% moisture, use SILCOR Primer BS or EPOCOTE F100W Clear where specified. For prepared concrete and masonry between 5.0% and 6.9% moisture, GCP nominates EPOCOTE F100W Clear.
Where direct-stick tiles, bonded screeds or topping slabs are installed, GCP requires the cured membrane to be compatibilised with a SILCOR 575 HB or 575 LB tie coat and broadcast aggregate before the cementitious finish is applied.
Compare the other GCP SILCOR waterproofing products or the broader waterproofing membrane range.
What film thickness is required for SILCOR 575?
At least 1.75mm wet film thickness to achieve 1.5mm dry film thickness.
When can it be flood tested or tiled over?
After about 48 hours.
What elongation does it provide?
Greater than 500% to ASTM D412.
Does it need a topcoat when exposed?
Use SILCOR Top Coat 80 where the specified system requires a UV colour-stable, non-slip exposed finish.
| Property | Value |
|---|---|
| Base Chemistry | High solids, moisture curing polyurethane |
| Specific Gravity | 1.40 g/ml |
| Viscosity | 7,000 mPa.s |
| Solid Content | 91 %w/w |
| VOC Content | <110 g/L |
| Tack Free Time | 4 hours |
| Set Time | 6 hours |
| Min Recoat Time (23°C/60% RH) | 12 hours |
| Max Recoat Time (23°C/60% RH) | 48 hours |
| Min Through Cure Time (23°C/60% RH) | 48 hours |
| Rain Resistant Min Cure (23°C/60% RH) | 2 hours |
| Ready for Flood Testing/Topping (23°C/60% RH) | 48 hours |
| Shore A Hardness | > 65 °A |
| Tensile Strength | > 4.5 MPa (AS 4858), > 5.0 MPa (AS 4654.1) |
| Elongation | > 900 % (AS 4858), > 800 % (AS 4654.1) |
| Classification | Class III High Extensibility (AS 4858-2004, AS 4654.1-2012) |
| Movement Capability | Pass (No fatigue cracking exhibited) |
| Bond Strength | >48 N (AS 4654.1) |
| Water Vapour Transmission | 4.87 g/m²/24h |
| Water Resistance | Pass |
| Chemical Resistance | Pass |
| Resistance to Detergent Immersion | Pass |
| Heat Aging | Pass |
| Application Temperature Range (Substrate/Ambient) | +5°C to +35°C |
| Application Relative Humidity Range | 35% to 85% |
| Minimum Dry Film Thickness (General) | 1.5 mm |
| Shelf Life | 9 months |
| Recoat Time | 12 |
| Full Cure | 48 |
Here are some common examples on where SILCOR® 575 LB used by our customers.
