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How to seal and waterproof shed?

Hi! I am a property manager and have a washroom on site that is pretty old. We expanded it and added some storage areas. My issue is that when it rains the water comes in from underneath the shed and damages the wood doors to storage area. How would I go about extending the shed to the ground and waterproofing it. Here are some pics to better illustrate what I’m talking about. Thank you so much for any advice!

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EricL

Hello @islandermandie

Welcome to the Bunnings Workshop community. It's fantastic to have you join us, and thank you for sharing your question about sealing your shed.

Looking at the pictures that you posted it seems that water is running under your shed wall. Have you tried to put any barrier or sealer to prevent the water from coming in? One of the problems I see happening is that if sufficient rain were to pour down the interior wall would get wet and start to rot. Although a silicone sealer would stop the water from flowing in, it will not protect the wall from pooling water.

Can you please tell me what material was used for the wall of the shed? To be specific what kind of wall are we looking at in picture number three? The ideal repair to this would be to divert the rainwater from going to this area and seal the bottom part from getting wet. I suggest using Fielders 100 x 50mm x 1.8m Zinc Angle in combination with Selleys 290ml Clear Storm Waterproof Gutter And Roof Sealant. I propose running it from one end of the shed to the other to make sure that any water that flows towards that outside wall will get diverted. I suggest putting a generous amount of sealant on the floor and on the wall to make sure there will be no leaks.

Let me call on our experienced members @TedBear and @Jewelleryrescue for their recommendations.

If you need further assistance, please let us know.

Eric

islandermandie

Thank you for recommendation. The picture of the inside is just drywall. The outside is I believe redwood, but very old. I’m in San Diego and it does not rain much but since they part of the shed water gets diverted to I want to seal it.
How would I go about sealing the flashing to the cement? I’ll send better pictures but wanted to see about maybe adding some flashing to the doors inside the shed on the bottom to keep any water that may get into the shed I to the bottom of the doors.
Thanks again for help!

Jason

@islandermandie,

Great to see you have already received some great advice from Eric.

We've had a number of previous discussions about how to seal a shed. Let me point you in the direction of a few:

How to seal the bottom of shed walls? by @jjebw

How to seal the bottom of the shed? by @MattR85

How to waterproof existing garden shed? by @basilmabraham

How to water-seal edges of an Absco garden shed? by @bennyboy

Hope all the advice shared in those conversations will be helpful to you.

Jason

Jewelleryrescue

Hi @islandermandie

@EricL idea firstly of flashing around the walls as it will lock water out of that area if it is the only point of entry will work. But that locked out water will build up and flow around the corner possibly to a next low spot. But looking to the far back of that wall will the water flow around the corner and come in there? And that area looks like stones so flashing cant work there If so the water proofing will need to extend there too if possible.

Well some extra ideas to think about. Especially if the door is at all external as well it is hard to seal under that 100%

1 Fill under the shed with water proof cement 1 part , 3 sand. and trowel it to wall Add water proofing polymer as a plus

2 Cut a simple dish drain around the shed so water never builds up if there is a low point to divert too

3 Raise the cement level in the store room both sealing the outer wall and water wont flow up hill

4 depending on water depth there are specialtiy roller door wedge shape rubbers 1/4 inch to stop repel shallow water.

TedBear

Hi @islandermandie ,

from what I can make out, I tend to agree with the suggestions of @EricL .

The zinc angle with sealant should seal the outside wall-to-concrete sections but I'd consider using something like flashing tape

https://www.bunnings.com.au/consolidated-alloys-200mm-x-10m-weatherproof-byute-flash-flashing-tape_p1100474

or a straight zinc strip (200-300mm width) with sealant (but I couldn't see any on the Bunnings site) for any sections of wall that go to dirt. Dig it in to the soil to lower than the floor level so water will run off into the dirt. It wouldn't hurt to put some stones along those sections, as suggested by @Jewelleryrescue , to allow water to run away with less resistance than soil offers.

I would be wary of sealing the inside walls... it is better that they remain disconnected from the floor so they will be less likely to be affected by any internal sepage... which hopefully won't be there after sealing the outside.

I wonder if there is any seepage through the floor concrete from underneath? I guess you will find out once you seal the outside walls.

As for the door... I guess a rubber weather strip on the outside would be the best that you could do. You could put a rubber strip on the floor across the doorway just inside perhaps (I didn't see pics of the doorway), and mark it with yellow striped tape to alert people to the potential tripping hazard.

islandermandie

Thank you for all the advice. I have attached more picture to give a better understanding of what I’m dealing with.
this is the side of the shed and water runs down the cement slop from the street

this is the gap im trying to fill so water doesn’t come in

here is the back side of the shed

and here is inside the shed where the storage areas are located

they are unfortunately interior doors so one has already been damaged by a leak in the roof

im opening to any suggestions and really appreciate everyone’s help!

TedBear

Hi again @islandermandie

From those extra photos, it looks like there's an opportunity for some prevention as well as sealing the walls and door...

Would it be possible to lift that short section of path inside the gate and insert a channel section across the bottom to divert water away to the side where the dirt is? You'd need to install a small soakwell in the dirt for the diverted water to go into. That way less water will arrive at the shed, perhaps none.

Replace that sloping path section with paving bricks which will also help absorb water coming through the gate .

https://www.bunnings.com.au/everhard-1m-easydrain-compact-polymer-grate-and-channel_p4770222

https://www.bunnings.com.au/reln-soakwell-rapid-flow_p4770021

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