Ground Floor Patio / Rooftop Terrace - Installation Specifics

Two unique installation scenarios

Most of our projects involve balconies on floors 1 to 10 - typical apartment blocks, new developments, tenement buildings. But there are two types of spaces that require a special approach: the ground floor (ground-level balcony, patio, garden) and the roof (rooftop terrace, penthouses, flat roofs).

Both scenarios have unique advantages and challenges. A ground-floor balcony means easy access and a connection to the garden. A rooftop terrace offers panoramic views and privacy - but also wind, sun and the need to protect the waterproofing. In both cases, composite decking on joists works brilliantly, though the installation method needs to be adapted.

Ground floor - garden, patio, ground-level balcony

A ground-floor balcony (or as many developers call it - "garden", "patio", "private terrace") is an increasingly popular feature of new developments. A flat with your own slice of outdoor space that you step into straight from the living room. Often covering 10 - 25 m2 - significantly larger than a standard upper-floor balcony.

Ground-floor advantages - installation logistics

The first and most obvious advantage: easy material transport. On an 8th-floor balcony, every board (240 cm, approx. 5.5 kg) has to be carried up the stairwell, through the lift and through balcony doors. On the ground floor, materials are delivered directly to the site - from the van straight to the terrace, no hauling up stairs.

This translates to:

• Faster installation - less time on transport, more on the actual work
• No risk of damage - boards don't scrape against stairwell walls and door frames
• Ability to use longer boards - 400 cm boards are easy to carry in at ground level, but squeezing them through narrow balcony doors on the 5th floor can be tricky
• Lower labour cost - less physical work = faster and cheaper

Ground-floor substrate - soil, concrete or gravel?

This is where the ground floor's specifics begin. While balconies on upper floors always have a concrete slab as a substrate, the ground floor can vary:

Option 1: Concrete slab (developer-built patio)

The best scenario. The developer has poured a concrete slab with a slope away from the building - we mount joists on tape just like on a regular balcony. Quick, clean, no complications.

Option 2: Paving stones

A popular solution on housing estates. Paving is stable and has a slope - we lay joists directly on it (with anti-slip tape) or on low adjustable supports. The only requirement: the paving must be well-laid and not sink under load.

Option 3: Bare ground (soil, grass)

The most common scenario in house gardens and older estates. Installing boards directly on the ground is possible but requires preparation:

• Geotextile - a layer of water-permeable fabric that blocks weeds. Without it, plants will start growing up through the boards within a year
• Gravel layer - 5 - 15 cm of compacted gravel on the geotextile. Provides drainage, stability and airflow
• Adjustable supports - allow you to level out uneven ground and maintain a consistent floor height
• Slope away from the building - critical. Water must flow away from the house wall, not towards it

Ground moisture - how to deal with it

The biggest ground-floor challenge is ground moisture. Unlike a 5th-floor balcony, where rain is the only water source, at ground level moisture also comes from below - from the ground, after rainfall, when the water table is high.

That's why under-deck ventilation at ground level is even more important than on a balcony. The space between the boards and the substrate must be open at the edges - so air can circulate and dry out the structure. Closing off all edges with finishing strips without ventilation openings is a common mistake that leads to moisture build-up and unpleasant odours.

The WPC composite boards themselves have water absorption below 1% - moisture won't harm them. But the substrate beneath needs to breathe.

Integration with the garden

The ground floor offers a unique opportunity that no upper floor can match - a seamless transition from composite flooring to garden. Boards can extend from the terrace straight onto a garden path, around a seating area under a pergola or form a platform by the barbecue.

On an upper-floor balcony, the floor ends at the railing. On the ground floor, you set the boundaries yourself - and the only limits are your budget and imagination.

Privacy - screens, planters, pergolas

The ground floor also means less privacy. Neighbours, passers-by, residents on upper floors - everyone has a view of your terrace. That's why ground-floor spaces are often complemented with:

• Planters with vegetation - bamboo, ornamental grasses, columnar arborvitae create a natural screen
• Wooden or composite screens - vertical or horizontal slats
• Pergolas - provide shade and overhead cover

When planning composite flooring at ground level, it's worth factoring in the load from planters (a large planter with wet soil weighs 40 - 80 kg) and mounting points for pergolas or screens right from the start.

Roof - terrace on a flat roof and penthouse

A rooftop terrace is premium - panoramic views, maximum privacy, full sun exposure. But it's also the most demanding installation scenario. Every mistake can have serious consequences - from leaks into the flats below to damage to the building's thermal insulation.

Waterproofing - the absolute priority

On a flat roof, beneath the composite floor lies a waterproofing layer (PVC membrane, EPDM or torch-on bitumen felt) that protects the building's roof structure from water. Damaging this layer means leaks - and not into your balcony, but into the flat below (or multiple flats, if it's a flat roof over several apartments).

That's why rooftop installation follows ironclad rules:

• Absolute drilling ban - no anchors, screws or bolts into the membrane. Zero exceptions
• Supports with soft pads - rubber or EPDM, which cannot puncture or abrade the waterproofing
• Protection against mechanical damage - an additional layer of geotextile or protective mat on the membrane, under the supports
• Maintaining access to roof drains - panels above drains must be removable (inspection panels)
• No blocking of water flow - water must freely reach drains and gutters

Before installing flooring on a roof, we always check the waterproofing condition. If the membrane is old, damaged or leaking, installing decking without first repairing the waterproofing makes no sense - it's like painting walls in a room with a leaking roof.

Wind - the invisible threat

The higher you go, the stronger the wind. It's simple physics - wind speed increases with height, and on top of a building there's also an acceleration effect (wind flows around the building and speeds up at roof edges).

For composite flooring, wind means the risk of board uplift. A strong gust from below (e.g. from the roof edge) can catch a board edge and lever it up. On a 3rd-floor balcony, this is a rare problem. On a 10th-floor roof - it's real.

Solutions:

• Heavier supports or supports weighted with concrete
• Tighter joist spacing (20 - 25 cm instead of 30 cm) - more fixing points
• Extra clips - particularly at roof edges where wind force is greatest
• Edge trims and finishing strips - mechanically locking board edges
• Higher balustrades - legally required on roofs (min. 110 cm), which also shield the floor from wind

Sun - surface heating

A rooftop terrace, particularly one facing south, receives maximum sun exposure. Dark composite boards can heat up to 50 - 65 degrees C in full sun (with an air temperature of 30 degrees C). Light colours - to 40 - 50 degrees C.

What does this mean in practice?

• Light-coloured boards are strongly recommended on roofs with full sun exposure - less heating, more comfortable barefoot contact
• Thermal expansion - WPC boards expand in heat (approx. 1 mm per metre for a 30 degree C temperature change). Expansion gaps of 5 - 7 mm between boards compensate for this
• Fading - through-body coloured boards (like our BSD series) don't fade significantly, but after 2 - 3 seasons the colour may "warm up" slightly. This is natural and applies to all materials exposed to UV

Thermal insulation - an extra layer

Few people think about this, but composite flooring on a roof acts as an additional thermal insulation layer. The air gap between the boards and the membrane (5 - 15 cm on supports) creates a thermal buffer that:

• Reduces roof slab heating in summer (less heat penetrates to flats below)
• Protects the membrane from direct UV radiation (extending its lifespan)
• Reduces thermal shock from sudden weather changes

This isn't the main reason for installing decking on a roof, but it's a welcome side effect - especially for residents on the top floor who complain about summer heat.

Access and logistics - the rooftop challenge

Transporting materials to the roof is the most difficult part of the entire process. Options:

• Goods lift - if the building has one of adequate size (240 cm boards will fit, 400 cm - probably not)
• Stairwell - possible, but very labour-intensive on 10+ floors
• Hoist/crane - most efficient for large material quantities, but requires space to set up and building manager approval
• Through a window - a last resort, but sometimes the only option

Transport logistics are the main reason why rooftop installation costs more than a typical balcony. Estimate: 10 - 20% more for installation alone (not materials - those cost the same).

Comparison - ground floor vs roof

What to check before installation

Checklist - ground floor

• What type of substrate? (concrete, paving, soil, grass)
• Is there a slope away from the building? (if not - one needs to be created)
• Is the ground stable? (clay soil after rain is unstable)
• Is there access to the substrate from the garden side? (material transport)
• Are there elements to work around? (manholes, pipes, kerbs)
• Are planters, pergola or screens planned? (point loads)

Checklist - roof

• What is the waterproofing condition? (age, membrane type, any leaks)
• Where are the roof drains? (access must be maintained)
• What is the direction and degree of slope?
• Does the roof slab have sufficient load capacity? (building documentation)
• How will materials be delivered to the roof? (lift, stairwell, hoist)
• Does the building manager consent to the installation?
• What is the wind and sun exposure?

Our experience with both scenarios

At BalkonSetup, we have experience with both ground-floor gardens and rooftop terraces. Each of these projects required an individual approach:

• Ground floor on a new development - concrete slab with slope, standard joist-on-tape installation, LED lighting integrated into the boards. Surface area 18 m2, installed in 1 day
• Garden at a tenement building - soil with grass, geotextile + 10 cm gravel + adjustable supports required. Surface area 12 m2, substrate preparation 1 day + board installation 1 day
• Rooftop terrace on an apartment block - PVC membrane, adjustable supports with protective mat, tighter joist spacing (22 cm) due to wind on the 9th floor. Materials transported by hoist. Surface area 35 m2, installed over 3 days

In every case, the same system: LiDAR survey, computer simulation, CNC cutting, clip-based installation. The details differ - but the end result is identical: a precise, durable composite floor fitted to the millimetre.

Summary

Ground floor and roof are two installation extremes - easiest transport vs hardest, ground moisture vs waterproofing protection, no wind vs full exposure. But in both cases, WPC composite decking on a joist system is the optimal solution:

• Lightweight - 20 - 25 kg/m2 is a safe load for any structure
• No drilling - doesn't compromise roof waterproofing or ground-floor slabs
• Moisture-resistant - water absorption < 1%, whether from rain (roof) or ground (ground floor)
• Ventilated - the space under the boards ensures air circulation
• Reversible - clip-based installation allows trace-free disassembly

Whether your space is on the ground floor or on the roof - browse our board patterns and imagine how they'd look at your place. Leave the survey and quote to us.