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How to fix shed leak under door?

AWolff

My shed is leaking I think partially at least because the ground slopes towards one corner. It's then creeping under the shed door. I'm not sure if it's also because the metal wall panel next to the door isn't sealed properly where it joins the acrylic siding?

My main question is how do I fix this? Do I need to install some kind of drain or can I add concrete to make the ground less sloped into the shed? My fear is a shallow layer of concrete will simply break off, but the shed is fairly surrounded by building so installing a drain would be a mammoth task and ideally not necessary if i can just direct the water away from the building.

thanks so much!

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MitchellMc

Hi @AWolff,

Before looking at major drainage works, have you checked the condition of the bottom seal on the roller door?

Over time, these seals can become brittle, compressed and inflexible, which prevents them from conforming properly to the concrete surface. Even a small gap can allow water to creep underneath the door during heavy rain. If the seal is worn or damaged, replacing it would be a worthwhile first step.

It's also important to check whether the door itself is closing evenly against the concrete. A door that is slightly out of adjustment may leave gaps that allow water entry.

That said, if this corner is genuinely a low point where water is pooling against the shed, then even a good door seal will eventually be overwhelmed. Water has a habit of finding the path of least resistance.

Sealing the gap between the aluminium flashing and the concrete with a product such as Sikaflex would likely improve the situation, particularly if water is entering through that junction. However, if there is a significant volume of water building up against the shed, sealing one entry point often just forces the water to find another route inside.

If the ground levels are directing water towards the shed, the ideal solution is to intercept and redirect the water before it reaches the building. A surface grate drain installed across the affected area would generally be the most effective approach. This could discharge to a nearby stormwater connection, or even a collection pit positioned away from the shed if access is limited.

Adding a thin layer of concrete to alter the fall is usually not something I'd recommend. Unless it is mechanically bonded and thick enough to be durable, there is a good chance it will crack, delaminate or break away over time. Even if successful, it can be difficult to achieve enough fall to meaningfully redirect water.

Let me tag @Andy85, @robinbrar, @TestNameHello, and @krishnak, to see if they have any thoughts.

Please let me know if you have any questions.

Mitchell

MitchellMc

Hi again @AWolff,

I thought I'd also add a couple of guides for the benefit of yourself and others coming across this discussion: How to waterproof a shed and How to install a shed floor.

Mitchell

AWolff

@MitchellMc thanks, I think the seal on the door is ok but the concrete and metal foundation at the low end of the door is higher than the concrete so it creates a gap that means to seal cant sit flush against the ground. how would i fix that? Hopefully the photo explains what I mean

MitchellMc

Hi @AWolff,

Yes, that does make sense. Could you take a photo from the side so we can see how much the concrete is encroaching underneath the door seal? That would help determine how minor the issue is.

From what you've described, it sounds like the door seal can't fully contact the concrete slab because it's being lifted by the raised section of concrete. If that's the case, water could potentially get underneath the seal during heavy rain.

Without seeing the side profile, the only solution that comes to mind would be to grind back the concrete that's preventing the seal from sitting flush. If it's just excess surface concrete or a small high spot, that is often a relatively straightforward fix.

One other thing to keep in mind is that if the seal has been sitting against that raised section of concrete for an extended period, it may have become compressed or permanently deformed. In that case, even after the concrete is ground back, the seal might not fully recover its original shape and could still allow water through. If you find that's the case, replacing the door seal after correcting the concrete issue may be necessary to achieve a proper seal against the slab.

If you do decide to grind the concrete, please be aware that concrete grinding creates a significant amount of dust, including silica dust, which can be hazardous to your health. Make sure you wear appropriate PPE, including a properly fitted P2 respirator, safety glasses, hearing protection and suitable clothing. Where possible, use dust extraction or wet-cutting methods to minimise airborne dust and follow the manufacturer's safety instructions for any equipment being used.

A side-on photo should help us determine whether grinding is likely to be a practical solution in this case.

Mitchell

AWolff

Hi @MitchellMc here are some pics from the side and also from the inside of the shed. As you can see there is water damage to the wall panel as well. The concrete is a raised a little bit but it's also where the metal plate anchoring the main frame of the shed is secured so I don't think I can grind away the concrete as a solution. Do you have any ideas?

EricL

Hello @AWolff

Thank you so much for sharing those extra photos of your shed. It appears to me that water is somehow accumulating at that corner post. I can see that some form of sealant was placed in the corner and is not holding the water back. Looking at your very first photo it seems that the gap between your pavers and the concrete slab was covered with masonry or cement, but the very end does not have any cover and is filled with gardens sticks and debris.

I suspect that water is somehow entering the post itself from the top in a very slow leak and is bridging towards the corner and is forming a puddle that is creating that overflow into the shed. It's not to say that water is not entering the front, but water is entering through another spot.

I suggest doing a very thorough investigation on the post itself and see if water is somehow entering it from the top as it could be a roof leak. As with most leaks I always advise searching for the source so that it can be properly addressed. In this case there may be two sources, I suggest engaging the services of a leak detection specialist with a thermal scanner to rule out the possibility that water is coming through another spot.

Once the leak has been ruled out, you can then address sealing all the possible entry points at the bottom.

Let me call on our experienced members @Dave-1, @Nailbag, @DIY4Knuckleheds, @TedBear and @JoeAzza for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

TedBear

I had noticed the same thing as @EricL … that post looks very wet and all the steel on top of the raised cement area is rusty. This suggests that the water is seeping from above. If you can stand in there next time it rains maybe you will see how the water is entering.

Dave-1

Good Morning @AWolff

I am thinking of a two fold step to stop the water plus investigated why the post is so wet as @EricL and @TedBear have suggested.

You need a drain across the width of the garage if not longer just to catch excess water. The water then needs to be directed elsewhere.
For the door seal. You could add extra rubber to the base except for that riased part. So like a brick game piece when the door closes it matches up with the concrete profile.
You could smooth the roughness and install a thin rubber strip to create a flat surface on that raised section to make it more of a tighter seal (using the above idea as well)

That roller door to the right of the open door, does it leak as well?

Dave

Noyade

I was wondering if this area is the real culprit. Also disturbing is how far the leak travels along the concrete floor?

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