How to find where water leaks into shed?

[mcandrew]

I have a shed which leaks a LOT of water when it rains. However, I can't for the life of me find where the water is coming from. There is no water leaking down the walls internally, even in heavy rain. The other side of this flooded wall is a patio slab which is undercover. I know it's a long shot, but does anyone have any ideas or tricks for finding where the water is coming from? Thanks for any help.

[Jason]

Hi @mcandrew,

Can you please tell us what's on the other side of the roller door? My guess is that water is simply running from under the door and pooling at the lowest spot in your shed.

This is a common challenge and community members have previously shared plenty of helpful advice for sealing a shed from the elements. Please take a look at this previous discussions:

• How to water-seal edges of an Absco garden shed?

• How to seal the bottom of shed walls?

• How to seal a new garden shed from the elements?

• How to seal the bottom of the shed?

• How to waterproof existing shed?

• How to weatherproof existing shed?

Hope that helps get you started.

Jason

[mcandrew]

Thanks heaps for your reply, Jason! On the other side of the roller door is a drop of about 70mm from the slab to drainage gravel. Even in our heavier rain the water has not come over that slab lip so I don't believe it's the issue. When the water is first appearing it does not reach that roller door which is another giveaway. Thanks heaps for your response though.

[Noyade]

Hi @mcandrew 

Thinking and doodling - with rain outside.

Could rain be striking the roller door outside and dribbling in under it - to pool in the unleveled floor?

And...

Or when it dries out and when wet weather is next predicted - set up a chair inside the shed, ready to wait and watch. 😥

[EricL]

Hello @mcandrew

It's great that you've received excellent advice from my colleagues. Just to add to the suggestions made, I recommend doing your own investigation with the help of your garden hose. I propose taking the items out of your shed temporarily once all the water has dried off. Get your garden hose and spray the outside of your shed making sure that the outside is thoroughly drenched.

Walk back inside your shed and see if you can see any water trails coming into the shed floor. Once you've identified the water trails that will be the point of entry you'll need to block off. But as an overall repair to the area, I propose sealing the bottom area of the shed wall with Sikaflex 11FC. Sealing this part of your wall will at least eliminate it as a point of entry.

However, should rainwater pool on the floor again it increases the odds that the water is bridging along your shed wall somehow and is working its way to the floor. In the meantime, I recommend sweeping the water out and having that chair ready for the next downpour.

Please keep us updated with your progress,  we look forward to seeing your floor leak fixed.

Eric

[mcandrew]

Thanks @Noyade and @EricL !

After reading your suggestions I've checked that the walls hang lower than the slab and have attacked the outside with a hose. The only place I can see water coming in is under the roller door as described by @Noyade . I'll look into weatherproofing options for the doors (although water only seems to come in one which is interesting), if you have any suggestions, I'm all ears. Thanks again for your help.

[MitchellMc]

Hi @mcandrew,

You'll need to determine where the water is coming in from to perform any satisfactory weatherproofing. I'd suggest waiting until it rains next and heading out there every 15mins to check where the water is coming from. 

Your photo doesn't appear to show that your shed walls hang over a slab, as you have bottom channels sitting on top of the slab. With sheds with bottom channels that the walls sit inside, the perimeter of the concrete slab must have a recessed step where the channel sits. The step prevents the water that overflows the bottom channel from coming inside the shed. It might also be worth checking to see if your bottom channels have their lower side facing the exterior. These bottom channels fill up with water from the rain running down the exterior wall. If the lower lip of the bottom channel is facing the interior, water will overflow out of it into your shed. If you also don't have the recessed lip on your slab, you'll have a wet floor in your shed. I've created a rendering that should help illustrate the recessed slab and the bottom channel's lower lip.

Please let me know if you have further questions.

Mitchell