sealing a garden shed

homeren0

Hi,

I followed a community instruction to seal the bottom of a shed using sikaflex 11fc and after sealing and waiting for it to dry for a few days, I hosed down the area to see if it had sealed, but water was still seeping into the inside of the shed from each groove that we sealed. Also I noticed some sealant were coming off the shed already. I thought I had cleaned it enough. Are there any other products that we can use to fill those areas completely? Seems like we would have to use a lot of sikaflex 11fc otherwise. Will we also need to seal the inside grooves too? Thanks!

MitchellMc

Welcome to the Bunnings Workshop community @homeren0. It's terrific to have you join us, and many thanks for your question about sealing a shed.

This is one of those situations where it really helps to understand how the shed is designed to manage water, particularly around those vertical grooves in the wall panels.

Most metal sheds are designed with a bottom C-channel that is fixed to the slab or base. The wall panels then slot down into that channel. Importantly, that channel has two different height lips. The higher lip should always be on the inside of the shed and the lower lip on the outside. When rain runs down the grooves in the wall panels, it is normal for water to enter the channel, but because the inside lip is higher, the water is forced to spill back out over the lower outside lip rather than into the shed. When everything is installed correctly, no water should be able to enter the shed, even though water is present in those grooves.

If the channel has been installed the wrong way around, with the shorter lip on the inside and the higher lip on the outside, water will run down the panel grooves and straight into the shed. In that situation, you end up fighting a constant battle with sealants because water is sitting in those channels and will always try to find a way through. That could also explain why the Sikaflex is already peeling away, as it is not designed to act as a permanent dam holding standing water.

It would be worth checking whether you have a continuous bottom channel under the panels all the way around the shed, and then measuring the lip height on the inside versus the outside. If the higher lip is on the inside, the system should work as intended and there should be no need to seal the panel grooves at all. The only sealing required would be under the base channel where it meets the concrete slab, to stop water tracking underneath.

If the channel is the wrong way around, sealing the grooves inside or outside will only ever be a temporary fix and you will likely keep seeing water ingress. Have a look at the orientation of that base channel and let us know what you find, and we can then work through the best next step with you.

Please let me know if you have any questions.

Mitchell