How to fix a leaking shed?

rebelliouskiwi

I have a house with an old kitset shed on a concrete slab, however when it rains, the shed leaks.

Is it possible to put a smaller raised concrete slab on top of the old concrete if it is in good condition, like these instructions I found?

What materials would I need to add the concrete? Timber to create a frame etc? Recommended products that would help me?

Obviously I need to remove the shed before doing so, which is not a problem and measure the shed. I'm guessimating 3m x 2m.

What sort of measurements would the raised slab be if it was a 2m x 3m?

And what sort of time frame would it be to properly cure the cement before I can put the shed back on the concrete?

Many thanks

MitchellMc

Hi @rebelliouskiwi,

Thank you for your question about creating a raised lip in your garden shed to prevent water ingress.

Ideally this is done when the original slab is poured, however it is likely you can create a lip like this with an existing slab.

To start, you’ll need timber boards to create a frame that matches the footprint of the new slab, slightly larger than the shed base (3m x 2m). The rebated lip can be formed by positioning a secondary, raised section around the edges of the frame, around 20-30mm high. This lip will help to divert any runoff.

For the concrete, a pre-mix concrete bag should work well for a slab of this size. After pouring, allow the new slab to cure for a minimum of 7 days; however, 28 days is ideal for a full cure. This will ensure the slab is strong enough to support the weight of the shed.

Alternatively, you might like to check out this article: How to waterproof a shed floor. This might be worth trying before removing the shed and altering the slab.

Please let me know if you have any questions.

Mitchell