On roof, terrace, balcony, walkway and podium projects, screed is often treated as a technical detail; however, that detail can influence programme certainty, water use, weather exposure and the sequencing of follow-on trades.
In a market where construction teams are already managing planning, regulatory and financial pressures, avoidable waiting time on site is becoming harder to absorb. RICS’ Q3 2025 UK Construction Monitor reported that financial constraints and planning and regulatory issues remained the most frequently cited impediments to construction activity, highlighted by 61% and 62% of respondents respectively.
A screed may be required to create falls, level an uneven substrate or provide a stable base for the specified waterproofing system. If that layer takes longer than expected to cure, introduces moisture into the build-up, or is affected by site conditions, it can place pressure on the wider programme.
For specifiers and contractors, the question is no longer simply whether a screed performs. It is whether the screed supports the project’s risk profile.
From product choice to project risk
Traditional cementitious screeds remain widely used and suitable for many applications. The specification question is whether their curing profile supports the programme, site conditions and risk position of the project.
On exposed roof and deck areas, curing and drying times can be influenced by screed depth, temperature, moisture movement and weather conditions. Where a traditional screed requires an extended curing period, follow-on works such as waterproofing, finishing layers and site access may need to wait. On new and refurbishment projects, that waiting time can affect more than the trade sequence. It can influence disruption, cost control and stakeholder confidence.
Why water content is becoming a bigger consideration
Water use is receiving closer attention across construction. It is not only used visibly on site; it can also be part of the way materials are manufactured, installed and cured.
A traditional cementitious screed uses water as part of the mix, which also creates a curing and drying requirement that needs to be considered within the programme. IKO Permascreed LI takes a different approach. IKO Permascreed LI contains zero water as part of the finished product, so no water is added on site to form the screed and the material does not rely on water evaporation in the same way as traditional wet screeds.
Weather resilience is a specification issue
Weather has always affected construction, but tighter programmes have reduced the margin for delay. Where a screed relies on water-based curing, cold and wet conditions can create additional planning risk. In colder periods, freeze/thaw cycles may need to be considered where moisture is present in the material before it has reached the required condition.
IKO Permascreed LI is a mastic asphalt screed that sets as it cools. Because IKO Permascreed LI contains zero water as part of the finished product, it is not dependent on traditional water-based curing. This supports year-round installation. Subject to substrate assessment and project-specific technical considerations. It gives, however, give project teams a screed option that is less dependent on the curing behaviour of wet trade materials.
Faster progress is not just about speed
Fast installation is often presented as a product benefit, but the more useful point is what it enables.
If a screed can be accessed sooner, follow-on trades can progress with less waiting time. That can support waterproofing, insulation, surfacing and handover sequences. It can also be valuable where the building remains occupied or where access needs to be carefully managed.
IKO Permascreed LI is designed to create drainage falls, level uneven substrates and provide a stable base for specified roof waterproofing and deck surfacing systems. IKO Permascreed LI sets as it cools and, subject to ambient temperatures and site conditions, thickness, can typically be accessed within 1-2 hours, allowing follow-on work to take place without delay.
For project teams, this can support better sequencing and reduce the waiting time often associated with traditional cementitious screeds.
Supporting the wider roof and deck build-up
The value of a screed is not only in how quickly it can be laid. It also needs to support the wider system.
IKO Permascreed LI can be used on flat roofs, walkways, terraces and podiums. It can help create drainage falls, level uneven substrates and provide a stable base for the specified roof or deck waterproofing system.
IKO Permascreed LI mastic asphalt screed is manufactured in accordance with BS EN 13108-6 and is listed as a screed material in BS 6229:2025 – Code of practice for flat roofs with continuously supported flexible roof coverings.
Making embodied carbon claims clear and evidence-led
As project teams look more closely at embodied carbon, screed specification needs to be supported by clear, comparable information.
IKO Permascreed LI offers up to 38% lower embodied carbon compared with the original IKO Permascreed product, supported by third-party verified EPD data. This gives specifiers a clearer basis for assessing the screed layer within the wider roof or deck build-up, particularly where embodied carbon is being considered alongside programme, buildability and performance.
Rethinking the screed decision
The choice between a cementitious screed and IKO Permascreed LI should not be framed as traditional versus modern. Cementitious screeds remain appropriate in many settings.
The more useful question is whether the screed supports the specific project conditions. Where programme certainty, seasonal installation, moisture management and embodied carbon are all under scrutiny, IKO Permascreed LI gives specifiers and contractors another option to consider.
Its value sits not only in the material itself, but in the way it can help reduce some of the risks associated with roof and deck sequencing.
Planning your next project
Screed specification can have a direct impact on programme certainty, weather resilience and the way water is used across a project. Where traditional cementitious screeds create challenges around curing time, moisture and seasonal installation, IKO Permascreed LI gives project teams a practical alternative to consider.
To understand whether IKO Permascreed LI is suitable for your next roof, terrace, balcony, walkway or podium project, contact IKO for project-specific guidance or download the latest IKO Permascreed LI literature.
