How to waterproof a new shed?

[slacker878]

Hi,

@MitchellMc  @Dave-1@EricL

I have read through the  post about waterproofing your shed. My shed is not built yet but my slab ready - but its not rebated.

I read about the U channels at the bottom of the shed.

My ideas are to use builder plastic inside the shed - see diagram to protect damp rising from the slab that had weep in from the side. (I am not sure if plastic sheet was below slab).

also to use plastic pallets as raised floors. i probably have to cut it down given shed is only ~ 800m wide.

Can anyone point out any issues with this plan?

Not sure about the sliding door bit yet. 

thanks!

[EricL]

Hello @slacker878 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about waterproofing your shed.

Linning the shed floor with builder's plastic and raising the items to be stored off the floor is a good idea. But please remember that moisture and condensation often get trapped inside the shed so if you are storing anything important inside the shed, I suggest putting it in an All Set 100L Grey And Green Heavy Duty Storage Container With Flat Lid. This will protect it from moisture and condensation, please do not use a cardboard box as the cardboard will absorb all the moisture and turn your item mouldy. 

In regards to the sliding door, just make sure to provide enough space for the door to fit in when you open your shed. 

If you need further assistance, please let us know.

Eric

[slacker878]

wont that decrease the humidity given that water wont evaporate from the concrete?

I don't understand this statement: In regards to the sliding door, just make sure to provide enough space for the door to fit in when you open your shed.

Is there a reason why no-one else has mentioned this method? many other posts about waterproofing shed but all focus on caulking below the walls. this still doesn't prevent water egress from when the U channels spill over?

this method, everything on the plastic sheet will be dry, and water can still be below the plastic sheet?

[EricL]

Hello @slacker878 

The method you are proposing prevents your items from getting wet, but it does not stop the water from coming into the shed. That is why the majority of posts refers to caulking the walls of the shed. This also explains why the "U" channel must be sealed with caulking to prevent water from gathering in the channel and entering the shed. Moisture and condensation will will often pass through any gap or space left open even with the builder's plastic moisture will enter through the gap of the roof, under the door and any space that is open.

If your shed's sliding door is mounted on the outside, then it is ok not to leave space for it when it moves on the wall. But if your sliding door is installed inside it will require space to move on the wall. If the plastic pallet is too close to the wall there will be no room for the sliding door to open. 

If you need further assistance, please let me know.

Eric

[slacker878]

ok thanks!

another question: https://www.workshop.bunnings.com.au/t5/How-To/How-to-waterproof-a-shed-floor/ba-p/151654

Mitchell's guide recommended sealing the outside edge of the U channel.

There are some shed manufactures eg stratco that recommend sealing inside edge of the U channel instead?

[EricL]

Hi @slacker878 

Just to be on the safe side, I would seal both sides just to make sure that water does not sit inside the "U" channel. 

If you need further assistance, please let us know.

Eric

[slacker878]

how does water not fill the U channel? rain will fill the U channel regardless.

I am talking about sealing the inside or outside edge of the U channel where it meets the ground. like what @MitchellMc suggested in his guide.

[EricL]

Hi @slacker878 

I was referring to filling the "U" channel itself and not just sealing from the bottom. But leaving it open is also an option as it is designed to drain away. 

Eric