I want to build a concrete slab (upon which a deck will be build later) at the foot of a brick wall (by foot I don't mean the foundation foot, I just mean where the brick meets the grade level). I hear that you can't make concrete and brick stick together. How do I deal with it? Do I leave a gap? What about water in that gap? Do I put some flashing?

Edit: There are also some practices about joints:


This means have a joint but seal it, basically. What do you think?

Note that I'll have a slight slope from the wall. I'm still puzzled what to do.

2 Answers 2


You can leave a gap of a about 3-4 inches (70-100 mm).

Fill the gap with gravel - you can go from coarse to fine as you go. This will ensure that there is a route for any water to drain away. If there is a lot of water you may want to go as far as installing a French Drain which has a pipe for removing the water rather than relying on percolation.

Another route is to make sure that there is a slight slope away from the wall.

  • 2
    Adding a french drain in this gap would be a very good method to drain water. Trying to connect directly to the bricks would not be a good idea. Apr 8, 2011 at 10:10

I'm not familiar with the materials (especially with the bricks) but when we build with earth (cob building) we tend to use "Deadmans" to assure connection between the two materials or to hold a harsh change in shape thats need some support. If you can drill holes in the bricks you can connect to it re-bars that will help you to minimize the gap when you pure the concrete. here, here and here you can see some examples for the principle - although here I've connected concrete and cob, but you can learn something from it. i just couldn't find any pictures on the net that shows exactly what i mean. also, know that cob is much more forgiving then bricks or concrete, so you need to plan well.

hope that helps.

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