How to attach concrete to wood?

Question

I'm planning a wooden table with concrete legs. I will use a U-shape or O-Shape for the legs. Should i use screws to attach the legs to the slab or is there a better way? I thought of placing a metal angle in the concrete but i dont know if its the perfect plan to prevent the table from wobbling (if thats the right word)

Answer 1

With out any design sketch, a good way to bond wood to concrete is using threaded anchors or threaded inserts

The dificutl part is placing these inside the concrete column, to be level and not get dirty from concrete.

So using a fairly large size, so its easier to clean later, and easier to screw into.

Basically you would then insert a metal shaft in the wooden part and use a long screw thaht goes throught the wooden shaft freely but its head will clam the shaft.. and when you screw it into the concrete threaded anchor you essentailly pull the wood tighlty to the concrete pilalr..

I could not find a diagram that illustrates this but this is picture depicts the concept

So imagine the top of the screw, the part of your wooden table.. and the bottom part the concrete pillar, but using the threaded insert, instead of that bolt in the picture.

I have seen this used in building public park benches, with wooden planks fastened to concrete pillars... it is highly durable and very vandal proof.

But you might consider putting in three studs per column.. Three, in a triangle shape.. as this helps stabilise heavy objects. Or four in a SQUARE shape.. Using 1 you will need some sort of cross member or brace.. 2 is almost useless as you still need cross members or braces.

Answer 2

In order to avoid splitting the concrete, the best mechanism seems to be to use metal brackets bolted to the wood that go round the horizontal part of the concrete legs.

Having screws into the concrete could lead to the concrete splitting, although a metal bracket embedded in the concrete could be strong enough for most purposes.