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How to seal the bottom of the shed?

MattR85
New Contributor

How to seal the bottom of the shed?

Hi all,

 

Just wanting some ideas on how to best waterproof and seal off the bottom of my shed.  There are sides with significantly bigger gaps of which one side I can only seal from the inside, as it's against a retaining wall & fence (not able to access the outside edge)

 

Appreciate any help on this.

 

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Vis-á-vis
Established Contributor

Re: Seal bottom of shed

You need a floor under the shed with a rebate at the edge for the shed walls to sit in. I don’t think you’ll ever be able to adequately seal that shed on a concrete floor. Sheds either need a slab built to fit with a rebated edge or an internal floor. 

Re: Seal bottom of shed

Well that ain't happening... So anyone else?

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Seal bottom of shed

Welcome to the Bunnings Workshop community @MattR85. It's great to have you join us, and many thanks for your question about sealing a shed floor.
 

You've chosen a particularly un-even location to place your shed on there. Are there any other options you could consider? At a minimum, you'd need a level surface or a rebated slab, as @Vis-á-vis has mentioned.

 

You could level the area with cement and then apply a gasket of Sikaflex 11FC directly under where the shed walls will sit on the concrete. While the 11FC is still tacky, the shed would be placed on top and secured to the concrete with Dynabolts. This will pull the shed down into the sealant and give a reasonable seal to the walls. However, the gaps you have currently are well outside the realms of this method.

 

Have you considered creating a floor within the shed of pavers? That wouldn't stop water from entering the shed but would keep the contents above it.

 

Please let me know if you have any questions.

 
Mitchell
 

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Vis-á-vis
Established Contributor

Re: Seal bottom of shed

Even with a relatively flat surface it is very difficult to seal anything going from one plane 90 degrees to another. That is why houses have flashings and are built above the earth or the have membranes continuing into the earth or terminated on a footing. You can’t really do any of these things in your situation. Only other thing you could do is pour a new slab inside the shed. It doesn’t need to be very thick if you aren’t storing heavy equipment. Even if you could come up 50mm on the inside then you’d have a raised platform that water can’t enter. If your shed is say 3x3m then you’d only need .5m of concrete. That is about 50 bags and mixing two bags at a time in a wheelbarrow could be done in a morning. 

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