Thoughts on pouring floor slab (Philippines)

[Lloyd]

I am about to pour a 4 inch thick, 20 ft by 30 ft cement floor slab. I am located in the Philippines. This will be on clay type soil.

I am wondering about reinforcement. I was thinking of digging

6 inch wide by 4 inch deep "trenches" spaced 10 feet apart, in the ground before pouring the slab to create a "backbone" that would hopefully strengthen the slab. This would effectively create a "beam" under the slab. The trenches would be in a tic-tac-toe configuration. If you look at the website below, I would keep the "trenches" in line with the concrete posts.

Would this help? Or would this cause problems?

I do not have access to reinforcing wire mesh, and they have indicated to me that rebar is not needed. I would like to reinforce the slab.

Any recommendations.

I have a website that shows the progress of the house being built:

Building a house in the Philippines is an experience you will never forget. There are many practices that would cause you to shudder.

[Glenn]

Many here will disagree with me but I would want #4 rebar, 24" each way, 100% tied. Personally, I would not do the trenches. However most *basement* floors around here are not reinforced. You didn't designate what the use was.

[Deputy Dumbya Dawg]

If you do go with the trenches why not put them under the area where the interior and exterior walls will be?

[Lloyd]

The trenches will be in line with the posts that support the roof. The interior walls (non-load bearing) will be in line with the posts. Essentially this house could be classed as post & beam type. There will not be any load-bearing walls.

[Jonny]

Minimum, do dig beams around the perimeter. Minimizes soil erosion that naturally will occur. Red lead paint application is a major concern in my book...