Vinyl vs. Heat: Hot Weather, Plastic Floors, and the Indoor Air Question

Hot weather affects the way interiors behave, not just the people living, working, and relaxing within them.

As temperatures rise, the materials inside a building are exposed to greater thermal stress. Surfaces warm up, air movement changes, and in commercial spaces, hospitality environments, retail settings, and residential projects, these conditions can make indoor air quality and material stability harder to ignore.

Flooring sits at the centre of that conversation. It covers large areas, stays in place for years, and forms part of the material environment people live, work, shop, eat, and move across every day. When the weather becomes more extreme, the question arises: what is the floor made from, and how does it behave under pressure?

Heat makes material choices matter

Many conventional resilient floors are based on PVC, also known as vinyl. PVC flooring relies on a wider material system of polymers, fillers, stabilisers, plasticisers, coatings, and adhesives. Modern products vary widely, and responsible manufacturers work within strict regulatory frameworks, but the underlying material question remains relevant: plastic-based floors can – and do – respond to heat in ways that deserve closer attention.

Phthalates are chemicals used to soften plastics such as PVC, but their presence raises concern because some can interfere with the body’s hormone system, adding another layer of scrutiny to plastic-based materials used across large interior surfaces.

Scientific studies have shown that temperature can increase emissions or migration from PVC/vinyl materials. In one study on PVC flooring containing DEHP, one of the most common phthalates, researchers found that “DEHP concentrations increased greatly” as temperature rose from 23°C to 61°C. The same study predicted that an increase from 23°C to 35°C in a home could raise combined gas- and particle-phase DEHP almost tenfold.

The point for specifiers is practical. Hotter interiors make it harder to treat material emissions as a background issue.

Poor ventilation raises the stakes

Indoor air quality is shaped by a combination of sources, temperature, ventilation, and exposure time. The UK Parliament POST briefing on indoor air quality notes that indoor pollutant sources include building materials and that pollutants can become concentrated in poorly ventilated buildings.

This matters in real projects. During hot weather, spaces may be sealed to reduce heat gain. In other buildings, ventilation may be inconsistent, particularly in older offices, compact retail units, temporary fit-outs, hospitality spaces, or residential rooms with limited airflow. Where air exchange is poor, emissions from materials have less opportunity to disperse.

Source control is a recognised indoor air quality strategy. ASHRAE states that one of the foremost approaches to improving indoor air quality is “reducing or minimizing indoor contaminant sources[, which can be achieved through] selection of construction materials, furnishings, and maintenance products with low emission rates.”

That is where flooring specification becomes a material health decision, as well as a design decision.

Karta starts from a different material position

Karta was created to challenge the conventions of resilient flooring. Instead of relying on plastics or petrochemicals, Karta is engineered from natural and recycled materials, with zero plastics, zero petrochemicals, zero SVOCs, and low VOCs. Its five-layer construction includes cork backing, a PEFC-certified wood fibre core, recycled leather mixed with natural resins and vegetable fats, high-definition print using biodegradable inks, and a Karta Plated® AC5-rated topcoat.

The wood fibre core is central to that performance story. Karta’s wood fibre board is produced from PEFC-certified recycled wood, sawdust, branches, twigs, and other tree by-products, bonded under high pressure and heat to create a dense, stable core designed to resist moisture, temperature fluctuations, and everyday wear.

The recycled leather layer also plays a structural role, adding durability, impact resistance, and stability to Karta wide planks while reclaiming leather offcuts that would otherwise enter waste streams.

This gives Karta a clear response to the hot weather question. The product is designed around material integrity rather than plastic dependency. It gives architects, designers, and specifiers a route away from PVC-based flooring, while still delivering the practical performance expected from a commercial floor.

Designed for hotter, harder-working interiors

The future of interiors will place more pressure on materials. Buildings will need to handle warmer summers, stronger solar gain, changing ventilation patterns, and faster commercial fit-out cycles. Flooring will need to do more than look convincing on day one.

A floor should be considered for what it releases, how it moves, how it is made, and how confidently it performs when conditions become less predictable.

That is the real issue with plastic-based flooring. It may be familiar, widely specified, and commercially convenient, but familiarity should not make a material system immune from deserved scrutiny. When heat can increase emissions or migration from PVC/vinyl materials, when poor ventilation can allow pollutants to concentrate indoors, and when temperature swings can affect dimensional stability, the specification conversation has to move beyond surface appearance alone.

Karta gives specifiers a cleaner starting point. Plastic-free. Low VOC. Zero SVOCs. Built with cork, wood fibre, and recycled leather. Designed for commercial use without relying on the plastic chemistry that makes vinyl vulnerable to questions under heat.

Reduce avoidable risk at source, choose materials with greater transparency, and specify floors designed for the conditions interiors now have to face.

Built for the Future

Hot weather exposes the weaknesses in conventional thinking. Karta was built for better choices.

Explore Karta’s plastic-free flooring for commercial interiors, or speak to our team about specifying a low-emission, future-ready alternative to vinyl and LVT. Get in touch with our sustainable flooring experts today.