What to use to seal Steel to Concrete

misty floyd

Hi Folks,
I've put up a steel shed on a concrete base. Its leaking at the base as the concrete base is wider/longer than the shed. So water is sitting on the base and making its way in. I've got to the point of bolting it down with raw bolts but I now need to seal it to stop water getting in. Does anyone know what I should use to seal it? At the base is angle iron bolted down to concrete. I believe silicon won't adhere to concrete, right?

Thanks for reading,

M Floyd

drag0n79

Strips of roofing felt applied with a blowtorch might do the trick.

ircoha

misty floyd wrote: »

Hi Folks,
I've put up a steel shed on a concrete base. Its leaking at the base as the concrete base is wider/longer than the shed. So water is sitting on the base and making its way in. I've got to the point of bolting it down with raw bolts but I now need to seal it to stop water getting in. Does anyone know what I should use to seal it? At the base is angle iron bolted down to concrete. I believe silicon won't adhere to concrete, right?

Thanks for reading,

M Floyd

wrong
The ideal way to do this is loosen the bolts, shim the angle iron up and run a good bead of silicone along the (dry, dust free) concrete where the angle iron is and take out the shims so as the weight of the shed will squeeze the silicone

misty floyd

Thanks for the replies. Really thought silicone wouldn't work but might give it a go. The roofing felt sounds a bit messy but I'm considering both options. Thanks!

Minder

If levering the structure up to get the silicon under the frame is too much, try sealing the concrete with a neat bonding agent before applying the silicon bead along the base of the frame.

niceirishfella

I actually have the exact same problem as misty -
Apologies if i ask a question please.

so,what "neat bonding agent" would you recommend minder?

Minder

I was thinking of something like Unibond PVA - used to coat rendering before plastering - but if you are buying a product, there are concrete sealers available at B&Q

niceirishfella

Hmmmmmmmmmm, thanks Minder, but that aint going to do my job at all. What i need is a like a large bead of Silicone or similar (say maybe an inch thick application) to apply round my steel frame where is meets the concrete at the base

- does anyone know where i could get this stuff???!!

Minder

You seem to have missed the point. The silicon will not bind to the dusty concrete surface, so you need to seal that first. Once the concrete is sealed, you apply a silicon bead around the base. B&Q sell both, get the silicon sealant in the plumbing section.

niceirishfella

no, I see and appreciate your advice minder, but that will just not work in my instance. Thats all

the GALL

I may have your answer
What you may try is the sealer that ground worker use to seal man hole rings. It comes in a coil and is abount an inch thick and as sticky as f**k(it also expands but don't quote me on that) as some one said raise the shed with shims and slip the sealer in. You'llk get it in a hardware's dont ask me the price I don't know. The weight of the shed when bolted down will keep it in place and even if it doesn't stick to the steel it will definitly stick to the concrete.

Minder

the GALL wrote: »

I may have your answer
What you may try is the sealer that ground worker use to seal man hole rings. It comes in a coil and is abount an inch thick and as sticky as f**k(it also expands but don't quote me on that) as some one said raise the shed with shims and slip the sealer in. You'llk get it in a hardware's dont ask me the price I don't know. The weight of the shed when bolted down will keep it in place and even if it doesn't stick to the steel it will definitly stick to the concrete.

Thats product is generally called densotape. It is available in the plumbing section of B&Q and comes as a roll of tape about an inch and a half wide.

the GALL

No, it's not called Densotape
That product is for plumber's
The one im on about is for ground workers
sealing biscuit's and rings

niceirishfella

I'd say the place you'd get it so would be with a good Civil engineering supply co. or the like?

Correct?

Minder

the GALL wrote: »

No, it's not called Densotape
That product is for plumber's
The one im on about is for ground workers
sealing biscuit's and rings

Multiflex is the stuff we use for sealing manhole rings. Don't know if the builders merchants in Ireland will stock that. Ask for an Elastomeric joint filler. Sikaflex is another brand, made in Ireland so you will probably be able to find that. Not sure they come in a coil though. Found this on another thread.

dowtchaboy wrote: »

However - I did phone Sika in Dublin 01 8620709 and believe it or not they will sell to you direct by post if you can't find it locally - one tube if you want. Helpful crowd.

Incidentally, NiceIrishfella, why do you need to fill such large gaps? Is the concrete base not level?

niceirishfella

yep , the concrete is level alright, but the cladding on the steel frame is about half and inch over the concrete and i wanted a product to fill the gap between the concrete and the cladding inclusive - and make a nice neat and tidy looking job out of it.
also, the shed is already bolted down - and therefore i dont want to be "shimmying" it up etc.

see the pics to understand.

Thanks,
Nif.

the GALL

niceirishfella wrote: »

I'd say the place you'd get it so would be with a good Civil engineering supply co. or the like?

Correct?

any hardware will stock this product

it'a called water bar/stop
it comes in a coil and is one inch squard by 5m it's made out of a tar substance and when it sets it goes ahrd and expands
I'll be in the builders providers tomorrow and ill get back to you

niceirishfella

Hi GALL,

Really appreciate that.......I was in B&Q today myself and there's nothing in there to suit at all.

Look forward to hearing from you.

Rgds,
NIF

drag0n79

Strips of roofing felt will do the job - no messing about. Just cut the felt into thin strips, say 3 inches wide, then use a blowtorch to stick it to the concrete and the shed (90 degree angle, on the outside of the shed). Overlap where you are joining strips. Very neat job. 5 years down the line if you need to repair it, just patch it up with more.

Minder

the GALL wrote: »

any hardware will stock this product

it'a called water bar/stop
it comes in a coil and is one inch squard by 5m it's made out of a tar substance and when it sets it goes ahrd and expands
I'll be in the builders providers tomorrow and ill get back to you

That'll do the job alright, but afaik waterstops are made to be sandwiched between objects. They are hydrophilic and will expand up to 400% if unrestricted.