Leaking Absco garden shed

[rosez]

Finally, after months of waiting my 2 Absco garden sheds are up and sitting on their concrete slabs. I want to store boxes of Xmas decorations and extra linen as well as garden tools and other stuff in them, so I don't want anything getting wet. The sheds are 2.6x3m and 3x3m.
When the guy came to do the slabs he said to put some Abelflex between the concrete and the bottom of the sheds and they should be watertight, oh and dynabolting them down should do the trick. My son bolted them down for me on the outside of the sheds, then I siliconed between the concrete and bottom of the sheds.
Had a bit of rain, both sheds leaked. There was water all over the floor a couple of cms in places.
Trimmed the Abelflex so that it was flush with the bottom of the sheds. Siliconed around the outside again. Rained, still leaking.
Put silicone on/around the bolts. Rained, still leaking, maybe not quite as much though. Siliconed around the bottom of the sheds on the inside. Rained, still leaking but only about 20% now.
The only thing is that I'm not sure what to do next? Water seems to be filling up on the outside and overflowing to the inside of the shed, but not all arond the sheds, only a couple of places in each shed. Son has suggested that we drill holes on the outside guttering so that the water has a chance to drain away more quickly. Surely these sheds are designed to keep the rain out???
Your help and suggestions would be very much appreciated.
Cheers.
Rosemarie

[r3nov8or]

What does the Absco seller say about it? If there is a channel around the bottom of the walls, I would imagine it should have a way of allowing water to drain to the outside.

Also, I believe it is better to only silcone seal on the side you want to stay dry, in your case on the inside (for shower screens it's the outside). This allows water to freely drain to the wet side.

[Oldsaltoz]

All I did was Sikaflex some PVC angle around the inside perimeter, no problems, cheap, quick.

[Boeing777]

The U shaped channel at the bottom of my shed was filling up with water and if the rain was heavy enough the little drain holes couldn't cope and it would overflow the top of the channel onto the inside of the shed. I ended up filling the channel on both sides with some dunlop floor levelling compound - so far so good :2tsup:

[rosez]

Thanks so much for your replies. I have contacted Absco and they have asked for photos of the shed and where it's leaking, so will do that. In the meantime, looks like my best bet would be to take off the silicone on the outside of the shed and see if that helps, before drilling holes on the outside of the channels. Will try that out next, fingers crossed.

[r3nov8or]

The U shaped channel at the bottom of my shed was filling up with water and if the rain was heavy enough the little drain holes couldn't cope and it would overflow the top of the channel onto the inside of the shed. I ended up filling the channel on both sides with some dunlop floor levelling compound - so far so good :2tsup:
It would make better sense design-wise if the U shaped channel was a J shaped channel, so it was higher on the inside that the outside... (I'm just guessing that's not already the case)

[Shedblog.com.au]

Hi, who did your slabs? Doesn't sound like they did them right? The correct way to do slabs for garden sheds is to have a rebated edge of approx 40 mm so the outside walls of a garden shed sit down on the rebate and the Finished floor level of the G/shed is 40mm higher on the inside. Then there is no need for silicon or any other waterproofing products.

[rosez]

Finally got my problem sorted out (albeit a couple of months ago). Scraped off the silicone from the outside of the shed and hey presto, doesn't leak any more. Thanks for all your kind advice. I have so many improvements to make around my house. Will no doubt need some more help with what I'm thinking of next, decking around the back of the house, so thanks in advance for any advice. Have been looking at posts about decks and realise I need to do lots of investigating before starting as it seems rather daunting at the moment.