Large concrete patio poured against the foundation - should it be tied to the foundation or not?

Question

Over a year ago I had a large concrete patio (24' x 26') poured.

This concrete patio butts up against the foundation of our home.

I'm unsure if it was tied into the foundation of the house or not, but I strongly suspect it was. I wasn't around for the entire installation, only arrived home when the contractor was screeding (unsure if that's the correct term, bear with me) the slab.

I'm worried that if it is tied to the foundation, it'll crack my foundation and cause water to leak into the basement.

The home is 12 years old, proper drain tile setup.

The foundation is wrapped with the dimpled plastic for drainage.

There is no expansion joint or whatever between the foundation and patio because the contractor said the plastic wrap was good enough.

The slab has several control joints.

Slab has rebar and wire mesh in it.

The patio has a good slope away from the house, it has no puddling in heavy rain, etc.

House is built on a hill so drainage in the area overall is quite good.

I live in Vancouver area, Canada. Our average winters barely ever hit freezing.

With all that info, can anyone answer if the slab should be tied to the foundation or not? Thanks!

Answer 1

From my experience they generally are not. Have you tried reaching out to the contractor and ask if this is something they do in general. They probably won't remember your house specifically but you could ask in general.

Answer 2

On the few jobs that I have tied a slab to a foundation there were engineering reasons for the tie. Most slabs are poured next to the stem wall and do sit on the footing. As long a slope away from the house to drain the water you should have no worries.

Answer 3

You do NOT want the new slab tied to your basement wall.

Basement walls are designed as 1) cantilever walls, or 2) “beams” supported at the top and bottom.

1) Cantilever walls have rebar placed near the OUTSIDE of the wall. (Tension side of wall when the wall bends.)

2) Walls designed as “beams” (supported at the top and bottom) have rebar placed near the INSIDE of the wall. (The tension side when the wall bends.)

When you tie the slab to the top of the wall, you change the tensile side from the outside to the inside of the wall.

This doesn’t mean that you’d have “failure”, because the rebar could be placed in the middle of the wall. It depends on soil conditions, height of wall, subterranean drainage, etc.