Crumbly, crystal-like white stuff on concrete

C

Caveat

Registered User
Messages
4,007
Anyone know exactly what this is and if I should be worried?

Discovered on a bare concrete floor running along a crack.
Is it one of the many manifestations of damp?

Certainly smells damp - it brushes off easily.

Any ideas?
 
Efflorescence/bloom? If it is then it's normal as far as I know and often occurs on (e.g. red) brickwork. The crack may or may not be a cause for concern though.
 
Thanks Clubman

This had crossed my mind, but thought efflorescence only related to external materials, particularly, as you say, red brickwork?

Never heard of this happening indoors or on a floor for that matter
 
Lay out a sheet of plastic down on it overnight, in the morning lift
it and see if there is any condensation on the underside of
the plastic....if there is then hey presto you've a damp problem:D

good luck
 
kiwijbob said:
see if there is any condensation on the underside of
the plastic....if there is then hey presto you've a damp problem:D
good luck
Click to expand...

Ok...did that and there was condensation. On reflection, the white stuff I described is more like candy floss than anything else.

Any further advice? (other than calling damp specialist)

Thanks
 
Last edited:
If this is on an old (well cured) concrete floor you have a problem as the efflorescence (salts within the concrete mix) are being leached out by the presence of moisture- presumably from a leak or defective damp proof course. If this is a relatively recent phenomenon this may be indicative of a plumbing leak. Underfloor leaks can be difficult to detect as the water will track and the visual clues you see may not be the actual site of the problem. Unless you know where joints in pipework are it may be best to engage the services of a specialist leak detection company- may save you a lot of disturbance to you otherwise sound floor. It would be a good idea to contact a plumber first to establish if the plumbing systems are losing water in the first place- this will confirm a leak and its severity.
 
Thanks Carpenter

House is 25 years old - but we've only been in 7 months.

If this is efflorescence, and now that I have brushed it away, is there any indication as to the severity of the problem? i.e. if this returns in 1 month as opposed to 1 year? Or maybe it takes a long time to show up anyway - I don't know...

As for establishing if the plumbing is losing water could a mate who is handy do this - what is involved? Don't want to get professionals in unless absolutely necessary. If plumbing is OK is it fair to say more than likely a faulty dampseal is the cause - and if so, I'm guessing it's safe enough to leave this?
 
dble8 said:
where abouts in your house is it?
what room?
Click to expand...

It's in a spare bathroom which we stripped carpet out of when we moved in and have just left as is since - sort of used for storage at the minute.

Bungalow by the way
 
Last edited:
If you have an open heating system (tanks in attic) then you can see if there the storage tanks (one for domestic cold water and one for the expansion/ fill of the heating system) are filling, even when there are no appliances being used. Air in the rads can idicate a leak. I had a similar problem myself a few years ago and the builder tore up floors (in part only) to investigate pipework in the floor. Nothing was detected- I tracked down the fault later myself and the cause was a faulty radiator valve which was "weeping". Even though the volume of water was small it permeated into the floor and tracked along the walls and looked very like rising damp! The solution was very simple and cheap so elimininate all the possible causes before you start assuming the worst. If the fault is indeed a defective damp course it's very difficult to quantify how serious this maybe without seeing it, damp is damp and concrete floors should not be damp- not if you want your flooring to last.
 
Caveat said:
It's in a spare bathroom which we stripped carpet out of when we moved in and have just left as is since - sort of used for storage at the minute.

Bungalow by the way
Click to expand...

If it is in a bathroom it should be easily enough to isolate, probably faulty plumbing. I had that problem in a sitting room in my last house. House was about 30 years old. There was a basement underneath and we sealed it from the sitting room. It didn't cause any problems after that. Got a small time builder in for advice. These things happen in older houses all the time, I should know I am in the selling houses game!!!! If there is a rad in the bathroom, it is worth checking it - probably gun barrel piping used. If the house is standing this length of time it will go another 100 years standing. All houses have problems and the older MORE SOLID ones are more likely to suffer from plumbing difficulties but will probably stand longer than a lot of what is going up out there at the moment!! Nothing to worry about.
 
Ok thanks all

might just revert to my default response to these kinds of problems - and do nothing ;)

My reckoning is that if ground is not damp to touch, and there is no evidence of actual staining, then it can't be that bad.

Since tiles will eventually go on the floor I reckon they'll survive a bit of damp ok...
 
Last edited:
You must log in or register to reply here.
Back
Top