Which flashing to be used where corrugated wall meets concrete base?

[achintya88]

Hi Guys, I am planning to build a small shed with a timber frame and corrugated color bond sheets for wall and roof (like the attached image). The structure will sit on a concrete base. I just couldn't find what sort of flashing or seal I should be using where the corrugated wall meeting the base from stopping water to enter. 

[JacobZ]

Hi @achintya88,

A warm welcome to the Bunnings Workshop community and thank you for your question about waterproofing around the base of your shed.

There are a number of steps you can take to prevent water from entering your shed, with the gold standard starting at the pour of your concrete slab. 

If your concrete slab is not yet in place, I'd suggest pouring a slab with a rebated edge with a slight slope towards the outside as shown in the diagram below.

Having this rebated edge for the wall framing to sit in will ensure any water that does get under the edge of your shed can't continue up into the inside of your shed. With this setup, you can apply a bead of sealant such as Grey Sikaflex 11FC Purform along the inside edge of the rebate so any water that gets into the rebate will not continue up into the shed.

If you have already got a concrete slab in place and there is no rebate, I would suggest running the concrete flush with the edge of the slab, sealing the seam between the timber and the slab with Sikaflex 11FC and then attaching CAgroup 150mm x 30m x 500um Plascourse to the bottom plate of the timber and the outside of the concrete slab. You can then run the Colorbond sheets down over the edge of the concrete slab. See the below images as an example.

This will give you a very good seal that will prevent water from getting into your shed.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[achintya88]

Thank you, @JacobZ . This is great information! However, I have already poured the concrete slab larger than the shed I plan to build. Initially, my idea was simply to place a prefabricated shed on the slab, but now I want to construct a sturdier shed. Since it will have timber-framed walls, I will be able to hang my tools and add some DIY shelves and tool organizers.

[JacobZ]

Hi @achintya88,

How far back from the edge of the concrete are you planning on building the shed?

I can't say I'm aware of a flashing you can use to seal the shed when it is back set from the concrete.

You could use the Sikaflex 11FC to seal the bottom edge of the timber, but you would need to make sure it is one consistent bead with no gaps along the full length of the bottom plate. 

Let me know what you think.

Jacob