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

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

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.

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

20cm from the sides and back will be very different as it is at an angle. I have attached a shape of the concrete slab that's already in place. The size of the slab is about 3m wide x 4.5 long (on the shortest side). I am planning to put a shed 2.5 x 4 (10m2).

Screenshot 2024-12-18 at 8.19.29 PM.png

I do think I probably have to go on using Sikaflex 11FC to seal the bottom edge.

Also, I am thinking if I put my base timber in this channel and then use Sikaflex 11FC to seal , this will probably protect the timber from moisture

https://www.bunnings.com.au/siniat-92-x-3000mm-0-50bmt-steel-track-wall-siniat_p1091053?region_id=116240&gad_source=1&gclid=CjwKCAiAgoq7BhBxEiwAVcW0LNjG6KWeIp0GCmwyOre6hee1serx4L26WNpJtZEeTMGIyVJTMMYMmhoCAIEQAvD_BwE&gclsrc=aw.ds

Thanks

EricL

Hello @achintya88

I don't think using the Siniat 92 x 3000mm 0.50bmt Steel Track Wall Siniat is a good idea as it will tend to hold and gather water which is something you are trying to avoid. I would go with @JacobZ suggestion and use the CAgroup 150mm x 30m x 500um Plascourse.

If you need further assistance, please let us know.

Eric

Thanks, @EricL , Can I still use CAgroup 150mm x 30m x 500um Plascourse if the timber base is not on the edge of the concrete slab and on top (around 15cm from edge ) ?

EricL

Hi @achintya88

That's a good question, let us make a few inquiries regarding the position of Plascourse when it's not on the edge. As soon as we have more information, we'll get back to you.

Thank you for your patience.

Eric

Unfortunately, as @EricL has mentioned, the Siniat Wall Track would not be ideal in this situation.

You can use the CAgroup 150mm x 30m x 500um Plascourse to protect the timber from direct contact with the concrete. If you attach it to the underside of the bottom plate of your wall, it will protect the timber from moisture, however, it would only be protecting the timber, not acting in a sealing capacity like it would in my original post.

Unfortunately, using a bead of Sikaflex is about the best you can do with the framing set back from the edge of the slab.

Let me know if you have any further questions.

Jacob

Thank you, @JacobZ and @EricL . Your guidance has been invaluable.

another question which timber grade would be right for this project . The walls will be protected by color bond sheets ?