How to level an existing concrete slab?

Hi there,

I'm building a timber shed/workshop on an existing concrete slab. The plan is to build a timber framed shed that is slightly bigger (2.8m L x 1.8m W) then the previous aluminum tool shed. I've built the four frames and test fitted them to realize a slight problem.

As you can see from the pictures two front corners of the slab are considerably sloped (the height drop is about 21mm on one corner and 28 mm on the other)

Initially I thought of putting in wooden shims under the bottom plates of the timber frame to fill the gaps.

I'm just wondering if this might cause any issues later on due to the weight of the structure.

Or should I just level the concrete floor completely and start over?

Thanks in advance!

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MitchellMc

Welcome to the Bunnings Workshop community @Ned10. It's sensational to have you join us, and many thanks for your question about levelling on a slab.

I'd recommend packing shims instead of the timber at regular 300-400mm spacing across the span. Plastic packers are non-compressible and won't decay, unlike timber. You'll then be able to Dynabolt through the bottom of the frame into the concrete.

Levelling the slab is likely the best option, but obviously a much more involved process.

Please let me know if you have any questions.

Mitchell

Ned10

Hi Mitchell,

Thanks for the idea of using packing shims. I'll try that out.

EricL

Hi @Ned10

Your shed looks like a fantastic project. Please keep us updated with your progress. I'm keen to see what you'll be cladding it with.

If you need further assistance, please let us know.

Eric

Ned10

Hi Eric,

Thanks for reaching out. I'm hoping to go with Pine weatherboards for cladding.

Prior to cladding, I'm planning to cover the frame using OSB sheets but not sure of the thickness or the grade which I should be using.

I'm planning to put a layer of house wrap as well. Would you be able to recommend something for that?

The right side frame is quite close to the fence (about a 10 cm gap). So looks like I might have to complete that frame cladding on the ground first and then fix it in place.

Thanks!

EricL

Hi @Ned10

Thanks for getting back to us with that extra information. For the house wrap I suggest having a look at Ametalin Range. It provides insulation and and excellent water barrier properties.

Your idea of cladding and finishing the wall first is an excellent idea. Just as a suggestion have you considered leaving a space of 500mm on the side just in case you need to do repairs in the future or is there not enough space?

Eric

Ned10

Hi Eric,

I see what you mean. I've given it some thought and decided it's worth to leave more space between the fence and shed wall by shortening the front and back frames.

I may lose the floor space in the shed but hopefully that'll save any future frustrations.

Thanks for your suggestion.

EricL

Hi @Ned10

Please keep us in the loop, we look forward to seeing your shed come together.

Eric

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