Foundation for the patio roof

Terraces are usually oriented to the south. This implies that, of course, a lot of sun prevails. Many homeowners do not mind that for no reason. A patio roof is then the solution. But as with many other constructions we also need a foundation for the patio roof.

The different types of foundations

Already here first preliminary planning must be made. Because of course there are different foundations:

  • the dot foundation
  • the strip foundation
  • the plate foundation

Suitable foundations for the patio roof

Of course, you do not need a slab foundation for your patio roofing. The decision between a point foundation and a strip foundation is already more difficult. Of course, the workload for a point foundation is significantly lower. That also affects the costs.

Point foundation or strip foundation

However, a point foundation is also less sustainable. However, since it is a roof, you have to take into account additional loads to the actual weight of the patio roof: the possible snow load in winter and the wind loads during heavy autumn storms. This makes the strip foundation more realistic for many planned terrace roofs. Ultimately, however, the circumstances on the ground must always be weighed up.

Frost resistance of the foundations

Once the decision has been made, it is about the execution of the foundations. Regardless of which type of foundation you have chosen, every foundation must be frost-proof. This requires a minimum depth of at least 80 cm. But in some regions it can get even colder again. Then the excavation of the foundation is to be made deeper accordingly.

The gravel layer provides additional security

Although often dispensed with in a point foundation, a gravel layer of at least 10 cm thickness is recommended here as well. This provides additional frost protection. First, the water has enough room to drain, so it does not have to collect directly under the foundation.

On the other hand, leachate accumulates a little deeper under the foundation and has enough space to expand due to the cavities. In the case of a strip foundation, the gravel layer (with a grain size of 16/32) can also be up to 20 cm thick.

Making the foundations for the patio roof

If the ground is quite loose or sandy, at least the sides must be boarded. The gravel is compacted. Then comes a waterproof film over it. Now with a strip foundation the steel mesh is laid out. Then you can start casting the foundation. Finally, the foundation is compacted.

Compacting and waiting times for curing

If you do not have a concrete compressor, you can use a structural steel profile to repeatedly pierce the fresh concrete or hit the concrete with a shovel. Cover the foundation for one to two days to dry. By the way, you should not concretise at temperatures of five degrees Celsius and below. After two to three weeks curing time you can start with the actual setting of the posts for the patio roof.

Tips & Tricks

You can use different anchor shoes for the posts. Either those that are screwed with dowels after hardening of the foundation or those whose anchors are poured into the concrete. Both have advantages and disadvantages.

Product Image: brizmaker / Shutterstock

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