Der bessere Bodenbelag für Terrace on flat roof + garage
Step by step to the roof terrace
Der bessere Bodenbelag für Terrace on flat roof + garage
Neue Elemente braucht der Boden
Der bessere Bodenbelag für Terrace on flat roof + garage
Neue Elemente braucht der Boden
Der bessere Bodenbelag für Terrace on flat roof + garage
Neue Elemente braucht der Boden
Der bessere Bodenbelag für Terrace on flat roof + garage
Neue Elemente braucht der Boden

How do you install a terrace on a flat roof or garage roof?

You can really feel at home and sit together in pleasant company on a Mediterranean-style roof terrace decorated with citrus trees and laid out with WARCO terrace tiles in the Rattan Lounge colour scheme.

In many cases, the flat roof on a house or garage can be used very well as a terrace. Here you can find out how to build a terrace on a flat roof with little effort. You can easily carry out the work described yourself or hire a local craftsman.

Step-by-step guide to the perfect roof terrace

  1. Is the flat roof or garage suitable for use as a terrace?
  2. Which floor covering for the roof terrace?
  3. How do you lay a floor covering on a garage or flat roof?
  4. How do you lay terrace tiles on roofing felt or roofing membranes?

Is the flat roof or garage suitable for use as a terrace?

The construction of a terrace on a garage or flat roof is generally considered a change of use for the building in legal terms. Therefore, your first port of call is the building authority to find out whether you are eligible for planning permission.

If the garage is on the boundary of the property, you should coordinate your project with the neighbor to avoid disputes. And, of course, the structural conditions must be checked.

Load capacity
Can the roof be used as a terrace, what is the load-bearing capacity?

The load-bearing capacity of the structure must be checked, especially with a wooden roof and a garage roof or carport.

This is because the roof can only be walked on and used as a patio if the load-bearing capacity is sufficient for the patio floor and the additional load from people and patio furniture.
Is the roof impermeable? Is there any damage or wear to the roof waterproofing?

The service life of the roof waterproofing is limited, especially with bitumen membranes and roofing felt. It is therefore necessary to check whether the roof is watertight and will continue to remain watertight.

If there are any doubts, the surface should be completely renovated or repaired in places.
Slope angle
Is there a sufficient slope and functioning drainage?

Rainwater must be able to run off easily on the terrace. A slope of 1% to 2% towards the drain is usually sufficient.

By emptying a bucket of water, you can easily check on site whether there is a sufficient slope in the area that is inclined towards the drain.
Existing floor covering
Can the existing floor covering be used as a subfloor?

This depends on the material of the existing floor covering and its state of preservation. The material from which the new decking is to be made also plays an important role.

Weathered wood or WPC usually has to be removed.

Every flat roof must be permanently sealed against water ingress. Various materials can be used for waterproofing: Bitumen sheets, roofing felt, roofing membranes, flat roofing foil or a poured sealing compound.

The waterproofing is often the last layer on the roof and is therefore directly exposed to the weather.

Sometimes the waterproofing lies under a protective layer of building protection mats or a fill of gravel or chippings. If the roof is already being used as a terrace, the roof waterproofing is located under the floor covering. In the case of a stone floor or slabs on stilts, as well as a terrace made of wood or WPC, it is easily accessible. With tiles on screed, the waterproofing is rather inaccessible.

ALLESDICHT forms a seal on
any substrate forms a
highly elastic and
permanently dense rubber skin.

ALLESDICHT von WARCO ist die sichere Abdichtung für ein Flachdach oder ein Garagendach, die man einfach selbst aufgetragen kann. Nach dem Trocknen bildet ALLESDICHT eine dauerelastische und gut rissüberbrückende Gummihaut.
  • water-soluble - without toxins
  • process yourself according to instructions
  • for walls, floors and connections
  • Keeps tight against pressing water
  • entire area or partial area
  • on roofing felt, tiles, concrete etc.

Tip from an expert!

  • Terrace tiles from WARCO have a very low weight per unit area and are therefore also suitable for weak roof constructions.
  • Terrace tiles from WARCO can usually be laid directly on the existing roof waterproofing or on the concrete slab. It is not necessary to use pedestal supports or a thick layer of chippings, sand or mortar.
  • Terrace slabs from WARCO are usually laid directly on old and cracked terrace slabs made of concrete, natural stone or exposed aggregate concrete and also on tiles.

Which flooring for the roof terrace?

It is often possible to create a fantastic roof terrace on a garage roof or an attached room with little effort. Floor tiles from WARCO make it easier to design the roof terrace, as they are simply laid on top of the roof waterproofing. The family and pets will love the newly designed oasis of well-being on the flat roof.

Een goede vlonder moet veel dingen kunnen. Niet alle vereisten zijn echter op het eerste gezicht duidelijk. Sommige herkent de klant pas als de vloer al gelegd is en er onverwachte problemen opduiken.

The decking should look good and match the house. It should last a long time and require little maintenance. Slabs that break and crumble after just a few years or wooden planks that splinter and rot are bad.

If possible, the surface should be non-slip in dry and wet weather and thus offer a minimum level of safety. A surface with shock-absorbing properties (fall protection) is useful for children or older people.

With a sunny roof terrace in particular, it is important that the floor is well insulated, does not heat up too much and retains little heat. If buildings are close together, the floor should absorb sound or not allow it to arise in the first place.

The overall installation height and the weight of the flooring and substructure as well as the material and installation costs also play an important role.

Conscious selection - comparison of different materials

A roof terrace is being built on the concrete roof of a garage next to a house on a slope. To do this, the homeowner simply lays slate grey WARCO terrace tiles on the existing, flat garage roof.

Before deciding on a system, the available floor coverings should be compared on the basis of objective criteria:

  • Usage properties and technical data
  • Costs for the floor covering
  • Costs for installation and auxiliary material
  • Expenses for care, maintenance and servicing
  • Service life

In addition to the objective criteria, personal preferences and requirements also play a role in the comparison. However, you should not allow yourself to be guided too much by prejudices, promises or false expectations.

In the comparison, both offers from craftsmen and flooring systems for self-laying can be compared with each other.

Draw a sketch - The installation plan for the new terrace

Eine einfache Skizze, gezeichnet auf kariertem Papier oder auf Millimeterpapier, hilft dabei, den Bedarf an Terrassenplatten und Material für die neue Dachterrasse auf einer Garage zu ermitteln. In vielen Fällen ist es günstig, die WARCO-Platten von der Mitte der Fläche ausgehend zu verlegen.

Measure the future roof terrace and transfer the dimensions to a drawing. A sketch on squared paper at a scale of 1:100 is often sufficient, whereby 1 cm on the paper corresponds to 1 m on the roof terrace and a small box in the drawing represents a terrace slab measuring 50 x 50 cm.

Note irregularities in the surface, i.e. bulges, water drains, railings and steps.

Draw the new roof terrace flooring to scale in the drawing. Pay attention to the laying pattern and, in the case of concrete slabs, natural stone, WPC boards, wood or tiles, to the joints.

The sketch can be used to determine the exact amount of material required. And it is easy to see where you need to cut and where the resulting sections can still be laid out to fit. This saves material and avoids unnecessary offcuts and waste. In addition, the installation plan helps with the design of the new terrace by providing a visual impression of the finished terrace.

The installation plan is also a good aid when deciding which material the new roof terrace flooring should be made of. This is because the differences between the materials are clearly visible here.

How do you lay a floor covering on a garage or flat roof?

The work required to lay the new decking correctly depends on the material selected and the existing substrate. As a rule, the old decking must first be removed and a suitable new substructure built.

WARCO slabs are an exception, as the terrace slabs are usually laid directly onto the waterproofing of the flat roof or garage.

Planks made of wood or WPC
First, a stable substructure made of squared timber is built on the roof. The substructure lies on rubber granulate pads or pedestal supports and must be aligned horizontally.

Finally, the wooden planks or WPC boards are screwed or clamped onto the joists at a distance from each other.
Tiles and tiles
The screed is applied, leveled and smoothed on the carefully cleaned roof, which is covered with a PE film. Ensure a slope towards the drain and expansion joints.

Once the mortar has dried thoroughly, ceramic tiles or terra cotta tiles can be bonded with tile adhesive and then carefully grouted.
Concrete slabs, natural stone
Terrace slabs made of concrete, exposed aggregate concrete, natural stone or artificial stone are laid loose, i.e. with an open joint.A carefully leveled bed of chippings can be used as a base. However, the slabs are also often laid on plastic pedestals.Use a spirit level to ensure that the slabs are really level.
Panels from WARCO
WARCO tiles are usually laid directly on the existing substrate, for example on roofing felt, concrete, tiles or stone slabs, without any further preparatory work.

A layer of building protection mats or chippings should be removed. A fleece is required as a separating layer for plastic waterproofing membranes.

How do you lay WARCO terrace tiles on roofing felt or roofing membranes?

An extension with a flat roof is located between two detached houses. Its flat roof is designed as a terrace and thus made usable for the residents of the neighbouring houses. The roof terrace is made of red WARCO terrace tiles.
1. Unpack and distribute

One to two days before laying, you should unpack the new tiles from the pallet and spread them out or at least divide them into several small piles. 

When unpacking, you can lay the boards together according to colour shades, just as you would with parquet, wooden floorboards or natural stone. Of course, WARCO manufactures in such a way that the colour design of the panels appears as homogeneous as possible across the surface. A slight variation enlivens the surface and cannot be avoided.

2. Ensure the correct temperature

To ensure that the new terrace slabs lay well in both summer and winter, you should pay attention to the temperature when laying them. A cloudy sky and a constant temperature of 15 to 20°C is ideal. This is because WARCO slabs, like many other materials, are subject to thermal expansion.

3. Remove puddles on the waterproofing

Puddles should not remain permanently on the substrate of the roof terrace. This is because terrace slabs must not lie in water. Roofing membranes are often glued with little care and not parallel to the slope. Water collects between the overlaps of the individual sheets in rainy weather.

Use roofing felt to level out any unevenness in the substrate. Cut pieces of the roofing felt to fit the dent and level out any unevenness. The roofing felt can also be laid loosely on top of each other in several layers.

The sections of roofing felt do not rot and effectively displace the water. It couldn't be simpler or better!

4. Relocate longitudinal axis and transverse axis

First determine the centre point of the surface. To do this, stretch a string from the right rear corner to the left front corner and a second string from the left rear corner to the right front corner of the terrace. Place the first slab in the centre of the crossing point of the tensioned cords and align it.

The first step is to lay the first row of slabs along the longitudinal and transverse axes, starting from the centre slab. In other words, you add whole panels until you reach the edge area of the surface. If necessary, correct the alignment of the axes to create a pleasing patio floor.

5. Lay out entire panels on the surface

Now lay all the terrace slabs on the surface. Work your way from the centre and from the axes to the edges of the roof terrace. The WARCO terrace slabs are shaped in such a way that they join together to form a firmly contiguous slab surface during installation.

In many cases, laying from the centre of the surface towards the edges is more advisable than laying from a corner. This is because, on the one hand, the laid surface is much more attractive due to the symmetrical edges and, on the other hand, inaccuracies during laying do not add up over the entire length of the terrace, but over half the length at most.

6. Cut and attach the edge panels

The edge slabs are cut to size at the end of the installation process. In the best case scenario, one slab is cut in half for each row of slabs. One half of the slab is then placed at the beginning and one at the end of the row.

As a rule, however, the garage roof or the house roof does not match the dimensions of the slabs perfectly. In this case, a strip of suitable width is cut out of the centre of the panel to create two edge panels of the same size for a row of panels.

The patio slabs are laid flush against the house wall or the parapet on the garage roof, i.e. without a joint. With an open side, such as on a balcony, the slabs can protrude 2 to 3 cm above the floor slab.

The best way to cut the boards is with a saw for wood, a circular saw, jigsaw or sabre saw. The passage for the railing is best cut with a jigsaw.

Instructions as PDF for download

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The feel-good oasis for a short holiday at home

It is therefore very easy to create a pleasant and durable terrace on the roof of a garage or building with WARCO terrace tiles. With these instructions, even inexperienced craftsmen can do it.

Transform an unused flat roof into a feel-good oasis for your family. How about a roof garden? Flowering native plants and shrubs improve the air and create a pleasant microclimate. They are an important habitat for insects and provide privacy from your neighbours.

In the WARCO online shop you will find a large selection of patio slabs for owner-occupied, rented and let properties.

WARCO patio slabs are also favourable for tenants. This is because the handy slabs can be dismantled without damage when moving house and reused elsewhere, on a balcony, as well as for a patio in the garden, on the house or on a garage.

Use the WARCO APPs and plan to measure

In just a few steps, test your desired floor covering on site with your smartphone, or use our installation planner.

  1. Select your desired product and start the preview.
  2. Mark the area to be laid and select the appropriate colour.
  3. Determine the number of pieces of flooring required with the help of the installation planner.

Select floor covering for installation

AR App

The top products from WARCO for your roof terrace