The best waterproofing method depends on the construction, water exposure, movement, existing layers and how the surface will be used. A flat roof, tiled terrace and ground-contact wall are not interchangeable. Choose a complete assembly and its details, not simply a product whose label says waterproof.
This guide explains the main categories without prescribing a system for an unseen property. Manufacturer requirements, substrate testing and the actual design determine where each method is suitable.
Liquid-applied membranes
Liquid systems are applied to form a continuous membrane. They can suit complex detailing, but the selected system still has requirements for preparation, primer, reinforcement, thickness and application conditions. A continuous-looking surface is not proof that those requirements were met.
Sika's liquid-applied membrane overview describes this category and its range of technologies. Specific systems must be assessed for the particular substrate and whether the surface is exposed, protected or trafficked; a category description is not a job specification.
Ask how the installer will treat corners, outlets and penetrations, and how compatibility with any retained coating is established. Do not assume all liquid products can be applied over every old surface.
Sheet membrane systems
Sheet systems include different materials and installation methods. The design needs suitable seams or laps, fixings or bonding where relevant, and details at edges and penetrations. The visible open area is only one part of the system.
Ask what makes the specified sheet appropriate for the roof build-up and use. A protected terrace assembly may need different detailing from an exposed roof. The roofing service can assess the wider assembly where roof construction is part of the problem.
Cementitious coatings and compatible mineral treatments
Cement-based coatings are another waterproofing category, with properties depending on the particular system. They may be considered for appropriate mineral substrates and defined applications. Movement, cracks, water loading and compatibility still need assessment.
For an older wall, do not choose a dense coating simply because it looks durable. The wall's construction and moisture behaviour matter. Equally, a product suited to one water-retaining structure is not automatically suitable for an exposed roof or a terrace in regular use.
Ground-side waterproofing and drainage
A wall beside soil or higher ground faces a different water condition from a roof. The design may need ground-side waterproofing, drainage, a barrier or another coordinated approach. Safe access and the route by which collected water leaves the site must be considered.
An internal coating or horizontal injection should not be assumed to solve every below-ground problem. First distinguish lateral entry from capillary moisture and other sources. The rising damp guide explains why that diagnosis comes before selecting a treatment.
Four decisions that matter whichever method is chosen
1. Existing layers and substrate
Determine what is sound, wet, loose or incompatible. The quote should state what is removed, repaired and retained. Overlay is a design decision, not a universal shortcut.
2. Drainage and junctions
Waterproofing needs continuity at upstands, outlets, thresholds and penetrations. Drainage and movement joints should be addressed alongside the open surface.
3. Exposure and use
Consider UV, temperature, water loading and maintenance access according to the selected system. A surface used regularly by people needs appropriate protection and finish.
4. Installation and verification
The method should follow the relevant technical instructions and an agreed inspection record. Tests must suit the assembly; uncontrolled flooding is not a generic completion check.
Price the assembly, not the product bucket
Cost depends on preparation, access, removal, detail complexity and finish. Compare those boundaries when evaluating waterproofing proposals. A cheaper material price alone does not show the value of the installed repair.
Waterproofed's standard inspection is €100 plus 19% VAT (€119). Further tests and opening-up are separately quoted. Request an assessment with the location, existing surface, use and leak history so the method can be selected from the actual requirements rather than a general recommendation.
Frequently asked questions
Is liquid waterproofing always better than a sheet membrane?
No. Suitability depends on the assembly, substrate, detailing, exposure and use. Both categories contain different systems, and the installation design matters more than a general category ranking.
Can a new system go over the old waterproofing?
Sometimes, if the retained layers are sound and compatible and the selected system permits it. Investigation is needed; loose, wet or unsuitable layers may require removal.
Does one method suit roofs, terraces and basements?
Not automatically. They face different loading and use. A system must be assessed for its intended application and detailed as part of the complete assembly.