How to pour a concrete path next to a house?

[Sebastian90]

Hi Team,

I'm trying to figure out the best way to go about pouring a concrete path next to an old house. I've been told conflicting things- drill rebar into the foundations, and don't drill into the foundations. I'm not really sure what do to.

I've attached a couple of diagrams, the red indicates the rebar, the blue the mesh that would get attached. I was thinking the mesh and rebar would sit inside the new concrete. There are vertical facades on one side of each path.

Would it be beneficial to put a membrane down also?

Any advice welcome!

[MitchellMc]

Hi @Sebastian90,

Both approaches—connecting the concrete path to the foundation using rebar and keeping the path as an independent structure—have their merits, and the decision largely depends on the specific conditions of your site and what you're hoping to achieve long-term.

When you connect the concrete path to the foundation using rebar, the path will move with the house's foundation as it shifts over time. This can be beneficial if you're looking for uniformity and want to avoid any separation between the path and the foundation. However, if the foundation experiences significant movement, this could transfer stress to the path, potentially causing cracks in the concrete.

On the other hand, decoupling the path from the foundation creates an independent structure. This approach helps prevent the path from cracking in case of any foundation movement or settling over time. It gives each element—foundation and path—room to shift independently without affecting the other.

To further protect your path, you can lay builder's plastic underneath, which acts as a moisture barrier. This membrane helps prevent moisture in the soil from leeching up into the concrete, reducing the risk of cracking caused by moisture changes in the ground. It's a good idea to include this membrane for added durability, especially near old houses where drainage may be less efficient.

For the mesh and rebar placement, your plan sounds solid. The mesh and rebar should be placed inside the new concrete to reinforce the structure. The rebar, especially if you decide to connect it to the foundation, will add strength, while the mesh will help distribute any tension across the slab and minimize cracking. If you do decide to drill into the foundation, just be cautious of drilling too deeply, which could potentially weaken the structure.

Ultimately, both options—connecting or keeping the path independent—are viable, but I’d recommend thinking about the long-term movement of your foundation and how that might affect your concrete path. Personally, I'd probably go with having them separate and installation and expansion joint between the path and the house's foundation.

Please let me know if you have any questions.

Mitchell

[Sebastian90]

Thank you so much for your detailed response Mitchell, greatly appreciated. Just a couple of follow ups:
1- for the vertical rebar supporting "triangular" face of the path, could they just be hammered into the earth and then concrete poured on top, or is it better to not have the metal touching the earth and rather set them in concrete first? The finished height will be in line with the smaller section of the path.
2- I've already drilled some holes into the foundation, should I just fill those in if I went with ableflex?

thanks again!

[EricL]

Hello @Sebastian90 

It's better not to have the metal touching the earth as it is a pathway for moisture which will cause the rebar to rust and deteriorate. You'll notice in that in most concrete layouts the rebar is placed on little plastic chairs also known as Jack 25 - 40mm Plastic Reinforcing Bar Chair that lift the rebar off the ground so that when the concrete is poured the rebar ends up in the centre of the concrete slab.

In regards to the holes in the foundation using Able Flex to fill it should be just fine.

If you need further assistance, please let me know.

Eric

[Sebastian90]

Thank you Eric,

Can I just clarify, would I attach the expansion joint to the foundation and then pour the concrete? Will the joint stick to the concrete? Sorry I'm trying to find videos on silka ableflex but youtube is coming up short!

[EricL]

Hi @Sebastian90 

Please allow us to double check with our supplier regarding the proper procedure on how to place the AbelFlex when the concrete is being poured. As soon as we have more information, we'll get back to you.  

Thank you for your patience.

Eric

[MitchellMc]

Hi @Sebastian90,

You can run a bead of Sikaflex 11FC along the wall to stick the Ableflex with. However, you'd likely be best to use the Ormonoid 10 x 100mm x 25m Abelflex Self Adhesive Backed Expansion Joint Filler Foam. Once you've removed the backing you can stick it to your wall.

Mitchell

[Sebastian90]

Thanks so much again gentlemen, I really appreciate the advice. One final question! When choosing the MPA and aggregate size, my options are 25MPA or 32MPA, and 10mm and 20mm respectively. For a job like this, what would be the best combination? I would probably not think so hard about this if it wasn't for the exposed vertical face of the side of the path.

Thank you!

[JacobZ]

Hi @Sebastian90,

The higher the MPa, the higher the compressive strength of the concrete. Higher MPa concretes are used when there is a heavy load to be supported, such as in high-rise construction, civil construction or industrial applications. 25 MPa is roughly the standard strength of concrete, whereas 32MPa is a bit above average.

Aggregate size is similar in that the larger it is, the stronger the concrete is up to a certain point. If the aggregate is larger, the gaps between the aggregate are smaller meaning there is less cement paste, which is the weakest part of the concrete.

The downside to using a larger aggregate is that it is harder to get a smooth surface, so in your case, the smaller aggregate is likely a better choice.

Personally, I would go with the higher MPA with a smaller aggregate. This gives a nice balance between strength and ease of smoothing.

Let me know what you think.

Jacob