how much damp rises through a concrete slab

[DIYedboy]

I am building a shed in the garden. I'm making a concrete base 5" thick on top of rammed hardcore. The concrete will sit 4" agl and because the garden slopes, the concrete will be 14" thick and 14" agl at the other end.

I can't be bothered to blind the hardcore and put down a DPM. I just want to get the ready mix poured on top of the hardcore. I'll be storing tools in the shed so I don't want em goin rusty.

My question is, will the ground moisture be able to rise through the concrete and make the shed damp n rust me tools?

 

[elmsoft]

Absolutely! Damp will go through concrete with no problem at all!
Why one earth would anyone go to all that trouble and not " be bothered" to spend a few quid on a DPM?
Is this a joke - or a test?

 

[noseall]

Any damp arising through the floor slab will be subjective.

E.G. there is no point spending huge amounts protecting the slab if the walls and roof are going to be just a susceptible.

 

[^woody^]

I can't be bothered to answer

 

[noseall]

I can't be bothered to answer

Tough night?

 

[DIYedboy]

I'm amazed at your reactions...................it's a shed! it'll take loads more effort to blind all those naughty rough brick and concrete lumps! I thought concrete was waterproof.

Perhaps it would be easier to concrete it then apply 2 coats of bitumen onto the concrete n put a chipboard floor on top...............whatdya think?

 

[freddiemercurystwin]

Why don't you wrap all your tools in dpm instead?

 

[elmsoft]

I'm amazed at your reactions...................it's a shed! it'll take loads more effort to blind all those naughty rough brick and concrete lumps! I thought concrete was waterproof.

Perhaps it would be easier to concrete it then apply 2 coats of bitumen onto the concrete n put a chipboard floor on top...............whatdya think?

Well, concrete isn't waterproof! That is why you can buy DPM - and people sell a lot of it!

 

[gregers]

THERES NO SUCH THING AS RISING DAMP.

 

[themiddleagedun]

A concrete floor of a decent mix, and well tamped will be dry as snuff.
Garages hardly ever got a DPM years ago and were all OK.

 

[dormermike]

My garage has a dpm and is damp.. the wet car brings an awful lot of moisture in

 

[freddiemercurystwin]

Why not coat all of your tools in 2 coats of bitumen?

 

[ivixor]

Providing the shed is well ventilated, it will be fine. Any moisture will dry up and waft away, as it has done in non DPM buildings since the beginning of time. Very few sheds or garages and even houses were built with dpm until fairly recently.

 

[TonyW2]

Water pipes have been laid in concrete, corroded away and no water has leaked. Bird baths cast in concrete. So, is concrete porous or not? Or is it
down to the mix and compaction? Is a DPC just a belt and braces approach?

 

[noseall]

A concrete slab will get cold and will transmit cold so it will be a condensation trap. More so than any other surface particularly with the lack of polythene.

Polythene can also act as a barrier for unwanted sulphates etc.