ᐅ Is it possible to omit the blinding layer in this construction setup?

Hello,

I am planning to build a single-family house in the second half of the year, and as a layperson in the construction field, I will probably have a few questions over the coming months. It would be great if this community could help clarify some of the questions that may come up. Thank you in advance.

A construction company has offered me the following for the foundation/slab:

- Fine grading under the slab
- Excavation for strip footings measuring 45x80cm (18x31 inches)
- Strip footings concreted with C25-30 including structural reinforcement
- Installation of a dimpled membrane under the slab
- 10cm (4 inches) Jackodur perimeter insulation
- 20cm (8 inches) thick slab including reinforcement supplied and poured

Now to my main question: Is this slab construction generally acceptable, and can the use of a lean concrete layer be omitted in this setup, or is the lean concrete layer still absolutely necessary?

Thank you in advance for your answers.

Best regards

The blinding layer is not required for your construction setup. However, the “fine layout under the slab” should be carried out as accurately as possible. When we poured our slab, I paid close attention to ensure that the entire reinforcement was resting on spacers; I would recommend the same in your case. The reinforcement must be covered by concrete everywhere by about two finger widths (approximately), meaning it should not be directly on the perimeter insulation.

There is generally nothing wrong with the construction details, but only a structural engineer can assess them properly. On-site, you can ask your site manager for the reinforcement plan – this will at least show that you have a certain awareness of the quality of the workmanship.

@Knallkörper That reassures me a lot that there are generally no objections to the structure itself, as long as it is well executed. Thank you very much for your quick response!

Hello Mephisto23

The blinding layer is exactly what it says: a layer so you don’t have to work in the mud. You already have a dimpled membrane and an EPS underlay (perimeter insulation). That is clean enough. And as Knallkörper said: make sure the reinforcement has enough distance from the ground. People will be walking on the rebar, and it can happen that the spacers get pushed into the EPS.

Steven

@Steven Thanks to you as well for your reply. I will definitely be present during the foundation pouring to check the correct placement of the spacers/reinforcement.