ᐅ Start of House Construction / Laying the Foundation Slab / Tips

Hello everyone,

Our construction project has finally started after some back and forth about the foundation wall, since my neighbor is building with a basement and I am not.
We were able to reach an agreement, and today work began on the slab-on-grade (ground slab).
I’ve attached some photos.

- Do you have any general tips on what to watch for with the slab-on-grade?
- Are there essential things that need to be considered?
- No gravel layer, vapor barrier, or anything else was installed under the Jackodur insulation boards—should I accept this?
- When is a vapor barrier necessary?
- What should be considered regarding the steel reinforcement?
- What do I need to watch for during the concrete pour?
- Is there a vapor barrier to be installed afterward?

I have also attached the composition of the slab-on-grade according to the energy saving ordinance calculation.
It mentions an expanded polystyrene (EPS) foam type PS_035 under the concrete. However, I have not seen this installed at my neighbor’s place.
- Should I insist on including this?

- No Jackodur insulation boards were installed in the area of the foundation wall.
Can anyone explain why?
Doesn’t this create a thermal bridge?

I am really grateful for any advice, as my construction supervisor is out sick, and I want to prepare as much as possible before he can approve the slab in two weeks.

Please, no negative comments—save those. Constructive criticism is welcome anytime.
Use the time you would spend on negative remarks to enjoy a hot cup of tea and your free time.

Good luck.

How is this supposed to work without gravel under the foundation slab? The water will just wash the soil away.

Or were you simply not on site when it happened?

What do you mean by having an agreement with the neighbor? This is not your problem, and certainly not your expense.

You should pay attention to the foundation or the foundation soil.

Is there a reinforcement plan? Make sure the correct amount of steel is included.

If there is no waterproofing from below, then apply it from above before the screed is poured.

Measure the positions of the drains carefully.

And take photos of everything, also later during the shell construction phase; they are helpful.

Leergut64 schrieb:

Please avoid negative comments; save them for another time. Constructive criticism is always welcome.
The time you spend on negative comments, why not make yourself a hot tea and enjoy your free time instead.

You should have made yourself a tea...

tomtom79 schrieb:

How is this supposed to work without gravel under the foundation slab? The water will just wash the soil away.

Or were you simply not on site when this happened?

What do you mean by “agreed with the neighbor”? That’s not your problem and definitely not your expense.

You should pay attention to the foundation or grounding ring.

Is there a reinforcement plan? Make sure the correct amount of steel is used.

If there is no waterproofing from below, apply it from above before the screed goes down.

Measure the locations of the drains carefully.

And take photos of everything, including later during the shell construction; they will help.

Is that possibly the gravel or crushed stone layer? See attached image.

Is a bitumen membrane still needed above the foundation slab as a vapor barrier?

Very entertaining speech.

To the point: ground slabs can be constructed in very different ways, and poor workmanship is very frustrating. If you have reason to distrust your building partner, I would recommend finding someone on site to represent your construction supervisor while they are ill. As a layperson, you have limited ability to judge whether things are going well or not. Photo documentation is definitely a good idea.

Here you will encounter people who find the omission of gravel, crushed stone, or a thin layer of concrete beneath the slab catastrophic, and others who don’t consider it necessary. None of them know the geological conditions that determine the construction method. Ultimately, this will only increase your uncertainty—and it seems you don’t have a tough skin.

I will now continue my "miserable life."

Before the concrete slab is poured, your electrician must document and approve the grounding.