Complex solutions for leaking and energetically outdated flat roofs
Flat roof waterproofing is a complex system in which every element works together. It is not enough to simply cover the large roof surface with a new membrane: the professional design of the roof drains, parapet walls, flashings, chimneys, mechanical penetrations and every junction is equally important.
Leaks often originate precisely at these details. Cracks, blisters, open seams, damaged flashings or aged roof drains appearing on the surface may indicate that the waterproofing system requires renovation.
Our company undertakes the renovation of flat roofs on family homes, apartment blocks, public buildings and industrial properties alike, as well as the creation of new layer systems incorporating thermal insulation and waterproofing. The necessary technology is determined in each case based on the roof’s condition, existing layer structure and intended use.
Single-layer or two-layer waterproofing?
An existing bitumen waterproofing that is in suitable condition, stable and suitable for renovation can in certain cases be renovated with a single-layer system. In this case, a high-performance modified bitumen cap sheet is installed on the prepared and primed surface.
If the roof’s condition, the existing layer structure or the need for longer warranty security justifies it, we install a two-layer waterproofing system. In this case, the lower layer provides the appropriate base and load distribution between layers, while the upper, granule-surfaced cap sheet provides durable protection against weather and UV radiation.
We recommend the necessary layer structure based not solely on price, but on the roof’s technical condition and long-term safety.
The flat roof renovation workflow
Condition survey and defect detection
We examine the entire roof surface, the condition of the existing waterproofing, the falls, the drainage and every junction. We uncover the probable causes of leaks, and also inspect the parapet walls, flashings, roof drains and roof penetrations.
Based on the on-site survey, we determine whether the existing waterproofing can be renovated, and whether a single-layer or two-layer system is required, or possibly a complete layer system incorporating thermal insulation and waterproofing.
Stripping and preparatory works
We remove disused antennas, cables, fixed structures and those superstructures that hinder proper waterproofing. We clean the roof surface, remove loose and delaminated parts, and repair open seams and damaged surfaces.
Areas affected by blistering or moisture are opened up, repaired and treated from a vapour-control perspective as necessary.
Correction of falls and ponding water
Persistent ponding water on a flat roof can significantly accelerate the ageing of the waterproofing. In problematic areas we carry out fall correction where necessary, for example by using custom-cut tapered insulation elements.
Our aim is for precipitation to reach the roof drains or scuppers by the shortest possible route, without obstruction.
Renovation of roof drains and drainage elements
We strip out aged or improperly designed roof drains and replace them with elements suited to the new waterproofing system. We form a recessed, reinforced junction around the drains.
Where necessary, we also carry out the repair or replacement of scuppers, overflows and rainwater drainage connections.
Bitumen priming and substrate preparation
In the case of single-layer renovation, we treat the properly prepared substrate with a bitumen primer. The primer binds the surface dust and promotes proper adhesion of the new bitumen membrane.
In the case of a two-layer or vapour-control system, the lower membrane is installed according to the specified technology – for example, with partial torch-on adhesive or mechanical fastening.
Installation of vapour vents
Properly positioned vapour vents can assist the safe release of moisture trapped in the existing roof layers. Their number and layout are determined not by a template but by adapting to the roof’s size, design and layer structure.
Around the vapour vents we form a separately reinforced waterproofing node.
Installation of the waterproofing membranes
We install polyester-fleece reinforced, modified bitumen waterproofing membranes on the roof surface. The membranes are laid in the specified direction with appropriate overlaps.
The overlaps are torch-welded over their entire area, and at the joints a controlled bitumen bleed-out is formed. The mineral-granule surface of the top cap sheet protects the waterproofing from UV radiation and weathering.
Waterproofing of parapet walls, wall flashings and roof superstructures
Completing the horizontal roof surface alone is not sufficient. On parapet walls, wall flashings, chimneys, mechanical plant and other vertical junctions we carry the waterproofing up to the appropriate height and reinforce it.
At right-angled junctions we install bitumen fillets where required, which reduce tearing and stress on the membrane. We inspect the parapet flashings and wall flashings, and repair or replace them if necessary.
Retrofit thermal insulation and waterproofing for flat roofs
If the aim is not only to eliminate leaks but also to upgrade the building’s energy performance, we create a complete layer system incorporating thermal insulation and waterproofing.
Depending on the technical requirements, the layer system may include:
- aluminium-faced vapour barrier bitumen membrane;
- high compressive strength PIR or EPS thermal insulation;
- fall-forming EPS layer;
- mechanically fastened base sheet;
- modified bitumen cap sheet;
- new roof drains, vapour vents and node reinforcements.
The insulation boards are installed tightly butted, in multiple layers with staggered joints where required. The type, length and layout of the mechanical fixings are matched to the substrate, the insulation thickness and the roof’s usage.
A properly designed system simultaneously protects the building from precipitation, reduces winter heat loss and decreases summer overheating of the roof.
Why choose us?
- We work with several decades of family and professional experience.
- We look not only at the visible defect but also for the root cause of the leak.
- We prepare a detailed technical specification covering every detail of the roof.
- We install only reliable, verified quality materials.
- We carry out the work in accordance with the manufacturer’s application guidelines and the rules of the trade.
- We provide a written workmanship warranty of up to 10 years on waterproofing installed to the appropriate technical specifications.
A flat roof renovation is a long-term investment. With the correctly chosen layer structure, not only can the current leak be eliminated, but the building’s protection for decades can also be established.
Request an on-site survey and a detailed, itemised quote!
Problem with your roof?
After a free on-site survey we give you an itemised quote.