Metal Shed sealant

[Robbo60]

My 20 year old wooden shed has disintegrated and I have bought a metal one which doesn't have/need a base. It bolts to the concrete hard stand.
I think I need to seal around the base frame to the concrete to stop water ingress - any recommendations? Just been to B & Q and their "frame sealant" is for indoor use only.

 

[Woody2Shoes]

There's any number of suitable sealants for exterior use e.g. No Nonsense White Frame Sealant, 310ml | DIY at B&Q
The only drivers being suitably flexible and the right colour - once you've read the label to confirm it's suitable in all other regards.

Another alternative might be to put some self-levelling compound on the inside - so the 'floor' is elevated by 10-20mm above the 'footings' IYSWIM

 

[Racers]

How about the bitumen roof sealant a bead under the steel base would work well.

Pete

 

[Doug B]

I’ve been using Stixall externally recently to stick slate to a wall, it will stick to damp surfaces & is what the slate tile manufacturer recommended, I can’t believe how well it sticks they won’t come off when it’s cured.
https://www.toolstation.com/stixall-adhesive-sealant-290ml/p77137

 

[Robbo60]

Thanks all. I will be putting a waterproof "tarpaulin" on the floor and then OSB 12mm sheets on top of that. Incidentally I did price up shiplap etc to build one, but it was nearly as expensive as buying a metal one one from Sheds.co.uk - 10' X 6' £384. Base extended today. Build starts tomorrow

 

[Jameshow]

If you have a screwfix nearby then ebt sealant would be great. It's a sealant and an adhesive and will prevent anyone from trying to screw driver Thier way into your shed.

It's a cheaper version of 3M's 5100.

Cheers James

 

[Hornbeam]

When you are putting it onto a concrete base, you must ensure good runoff otherwise the water will pool next to the base and the sealant, meaning both more risk of leaks and also corrosion risk for the frame. Have a look at the sikaflex products. Dont be tempted by some of the cheaper own brands in my experience they dont perform anywhere near as well

 

[Lons]

Another consideration while the shed is still empty is to consider some insulaton as it's very likely to suffer from condensation, maybe a vent at each end as well.

 

[OldWood]

Yes insulation - but make sure there is a membrane in the INSIDE so that moist warm air doesn't end up condensing in the insulation.

 

[Robbo60]

Thanks guys. i think I'm going to go with the suggestion about the self levelling compound on the inside once it is fixed down, and run sealant around the external base. I'm only using it as a shed, not a workshop so will condensation be such a problem? It wasn't in my wooden one.

 

[Hornbeam]

Condensation will be much more of an issue in the metal shed. The timber provided a very small degree of insulation and also the thermal conductivities are massively different. (On a cold night pick up a piece of wood in one hand and steel in the other. Both are the same temperature but the steel feels much colder as it a much better conductor and draws the heat away better)
If you dont insulate then you must have very good ventillation
The self levelling inside will prevent water getting in but wont stop the frame sitting in any water that ponds outside. Your sealant needs to be a large fillet to shed water away from the frame. Also if the sealant fails at all it will trap water behind it accelerating corrosion. You could but down a perimeter of cement particle board at least 15mm thick and then bolt the frame down through this. This would lift the frame clear and also provide an edge to screed up to

 

[Lons]

Without insulation / good ventilation you're likely to think it's raining inside on some days assuming your shed is standard thin single panel steel. I have a 4 x 4.5m plastic shed which is not as bad as steel but it really is bl**dy awful sometimes and I'm not alone.