does anyone know anything about damp proof courses?

[norfolklass]

we bought our ground floor flat a couple of years ago (ex-local authority) so the council are the free-holders and liable for structural problems. I found a wet patch in the carpet in the corner of our spare room so I pulled up the carpet to investigate: the floor was absolutely sopping wet with puddles of standing water. first thought was condensation but none of the walls are wet. the building only consists of us and our neighbour upstairs, so all four boundary walls are external - like a detached house - but after checking the DPC outside it looks sound. as far as we can tell, the floor is solid concrete with old tiles laid straight over the top, then underlay then carpet both of which are soaked. we're worried that the DPC has failed or the recent cold weather has caused some kind of freeze/thaw damage and the people that I've spoken to at the council have mentioned the possibility of having to take up the old concrete floor in both bedrooms, lay a new one, and then re-plaster.

I know nothing about building type stuff, and the thought of having to have the floor replaced in at least two rooms fills me with dread... the council said they hoped to get an inspector out this week (this morning's guy was a plumber despite there being no pipes in the room) but it may take a while. in the mean time the carpets are still soaking wet, the furniture's piled up in the middle of the room and in the hall, and we're supposed to be having a new kitchen fitted in 6 weeks :(

is there any other possible explanation that anyone can think of?!? :-\

[norfolklass]

[glosterwomble]

burst/leaking pipe under concrete floor??

[Al37]

Does your spare room share a wall with or back onto the kitchen or bathroom?
If so there is a chance that there is a leaking pipe and it is eventually running along the floor to your spare room.
we had a similar problem and it turned out to be the bath waste pipe with a slight leak this ran under the bathroom lino and made the hall carpet wet.

[lottie lou]

Possible Causes: - 
Water service pipe - tend to runup side of house to the rear.  If it is lead, common up to 40 yrs ago, this can perish causing pin holes in the pipe to leak (normall after 60 yrs).  If pipe is not 2 ft underground, could freeze but this would have stopped your water supply.

Drains - A broken of cracked or blocked drain close by (this could be a storm drain), otherwise you would know by the smell

General - If it is an old house you probably have quarry tiles (these are normally red 6x 6 or 9x9).  They were most likely to have been laid on ash with a weak mortar mix.

Solid floors require a damp proof membrane up to the level of the damp proof course. 

If there is any damp to wall inside, plast should come off 1 metre above floor level and redone in a sand & cement mix.

The external DPC should be 150 mm (6") above ground level.

It is advisable to dig down on the external corner of building where water appears to be coming in

Hope this is of help

[lottie lou]

Sorry, no wish to alarm you and this is worst case scenario.

[Eristic]

When dealing with damp always look for the simplest causes first. Possible causes are mains water pipe damaged where it enters building, Gutters blocked/broken, external downpipes damaged or blocked, toilets overflowing or leak from upstairs. Is there any marks on the cieling?

[cocopops]

Maybe the recent frost/thaw has fragmented the old concrete base and allowed the water to penetrate.  Lottie Lou has given good advice.  Checked with OH (in the trade) who says that it is a pain to have the floors re-done but it will only take a few days but make sure that they cover the the re-decoration and loss of furnishings etc.

Good luck

[Slug_killer]

If you remove the standing water ,does it return ? or was the damp a one-off.

Are the bricks outside damp? both above and below the DPC (should be between courses 2 and 3 above ground). If the bricks are not wet then the source is internal, or below.

If below, like others say, its a water pipe of types.

Do you live in an area known for flooding? Has anyone else in the street noticed damp?

All DPC and pipes are made to with stand frost damage. If some cowboy put yours in, you would have known long ago.

Do you suffer from subsidence ? This could easily cause a break in a clay pipe.

The man from the council is by far your best bet. He'll have the correct equipment ie, damp meters; and know what to look for.

I shouldn't worry unduly until he has had a look.

[nilly71]

I would of thought, if it's the DPC then the walls would be mouldy.

A big cause in flats is an overflow pipe only leaking slightly, its not enough for the water to pour out but runs back along the overflow pipe and into the building. From ground level all looks ok, in freezing weather it tends to drip. Being concrete it will find its own route.

I lived in a towerblock and it happened a few times, the water traveled 5 floors before dripping through someones light socket.
A cracked pipe under the concrete floor is also a common problem.

Neil

[Pesky Wabbit]

norfolklass, do you, by any chance, live in Gaza, as persistant bombing could easily cause a broken  pipe !

[norfolklass]

thanks folks, for all your replies! OK, well as far as we know there are no pipes under the floor. all the central heating piping to the radiators run along the skirting boards - the only pipes in the spare bedroom are the two that feed the rad and they come through the wall from the airing cupboard. the spare room backs onto the bathroom and airing cupboard, then there's the loo, then the kitchen. all mains water and waste in and out of our flat and our upstairs neighbour runs through the kitchen, so the nearest pipes are three rooms away. we've taken off the bath panel and checked the boxing around the cistern and the kitchen cupboards and there are absolutely NO signs of any leaks so we don't think it's travelling in from another room.

there's no downpipe on that side of the building, and no obvious leaks or overflows in the guttering. as we haven't had any rain for ages any wet patches on the brickwork would be pretty obvious but everything looks absolutely bone dry... I've removed the wallpaper from the bottoms of the affected walls and the plaster underneath is also bone dry, as are the skirting boards so it's definitely a floor problem - there are no signs of any leaks from above. OH's latest theory is that it's a really bad case of condensation: the floors are really cold to the touch while the walls feel relatively warm, so he thinks any moist air is condensing on the floor tiles under the carpet. last night we removed a 2' strip of carpet from one edge of the room, washed and dried the floor and this morning it's still dry. we pulled up the carpet edges from the other wall, washed and dried the floor, put the carpet back down and it's wet again... this is why OH thinks condensation. just waiting for the council man to come and give us his verdict.
thanks again!

forgot to add: we also live on the top of a hill.

[organicandy]

Hi, ive come across this problem many times with me being a plasterer, concrete floors are a nightmare, firstly they act has a wick, by pulling all moisture out of the floor but dont be fooled by the walls being dry ,you will find that when the plaster has been put on the wall the plasterer will have stopped about 2 inch short of the floor for the same reason of if the plaster goes all the way to the floor it will also act has a wick (this is common practise), if your ex authority house is more than 30 years old chances are there is no vapour barrier underneath, but dont panic yet, firstly check alway around your property (outside and make sure there is nothing touching the walls (example, piled up soil, bricks,or any other materials close to or touching walls) secondly, make sure there is at least 2 course of brick showing under your dampcourse, if not . dig out if possible so you have a clear 2 bricks under dampcourse, check all downpipes for leekage and blocked guttering (hosepipe on roof if nessesary)thirdly, remember water runs down hill so the problem could be anywhere, i would recomend that you remove bath pannel firstly, fill bath with water and then pull out the plug and watch for leekage around the plumbing under bath,also any other places in your home where you can check easily ,eg, under sink and so on, failing all this chances are you have a frozen burst pipe which sorry to say but if its under your floor you do have to remove floor and 1 meter of plaster (but only if the plaster is showing signs of damp on the damp meter probe)  chances are that with the cold weather and frost of late it may just be because the ice has had plenty of time to sit around dampen everything , i would hire a heat blower and leave it in that corner for a few days and then monitor before paying expensive repair bills, hope this helps Andy

[norfolklass]

hi Andy, thanks for your reply. the property was built in the 1970s, 1973 I think. there's nothing piled up against the external walls: at the front of the property there are two brick courses visible under the DPC and by the time you reach the back wall of the property (the wall that's the worst affected) due to the slope the flat is built, on the DPC is nearly 3 feet above ground level so is completely open to the weather all the way around the building. I will definitely try and check the guttering (will get OH on the case) and will try the bath thing tonight.
the good news is that as we're leaseholders and the council are the freeholders they should be liable for any repairs, depending on what the specific problem is, but the bad news is that it could take months for them to sort out. thanks again for your help I really appreciate it, especially as you're a plasterer and have come across this problem before.

[telboy]

Intrigued by this nfl.
Seems you've checked the most obvious points. Even if you're on top of a hill, a spring could be the culprit as our village has springs come up all over place.
I would guess the problem is under the floor. Even in the 1970's, damp proof membranes were used under concrete flooring but something is forcing water up somehow, albeit slowly.
Do you have screed on top of the concrete slab?
Keep us informed of progress, hope it's resolved soon - water is insidious stuff!

[norfolklass]

the council plumber guy said there was a 3" screed. I've been hassling the council to try and speed things up and should hear from the head of plumbing and all things leaky today to arrange an appointment for an inspector to come and have a poke about. hopefully he'll be able to pinpoint the problem then we'll know exactly what we're dealing with. OH is still convinced it's condensation - there was a light film of it on the exposed bit of floor this morning (floor is SO cold to the touch that the cat won't walk on it!) - but whether or not condensation is to blame for such a huge wet patch I don't know...

[Flunky]

I used to install chemical DPC.

What Andy has said just about sums it up. The wick effect is a true possibility if the plaster has not been finished above the floor (not touching).

The reason you remove the plaster is salt contamination. They are hygroscopic salts which attract water. So. if left to dry they will be, well, DRY. lol. Any moisture in the air would then be attarcted back and if it cant evaporate then "damp"pataches will appear again sometimes yellow stains. If this process continues then you will get "chrystal" type salt deposits on the plaster, if left long enough the plaster may blow.

The water must have a source (obviously LOL). It will be migratiojn of water through the floor slab. Lateral penetration from the outside (rain, pipe leak etc) or failure of the damp course. I doubt very much it will be failure due to age and you have said your ground levels are 3 ft below the DPC.

Hope that helps

F.

Fellow Narfook boi.

Edit - A dehumidifier would be better than heat blower (hire one) as that moisture has to go somewhere and if its into the room it will then settle on a COLD surface and you are back to square one again.

Condensation is not TOO cold or TOO hot it is extremes of these. A balance of these and adequate vetilation will solve the problem.

Also, one to remember, if you get black mould appearing its condensation for definate not damp as the salts that come with damp kill the mould.

[norfolklass]

thanks Flunky

Fellow Narfook boi.

;D

edit: we bought a dehumidifier when the council guy who came out in August 2006 said it was condensation, and we use it daily in the spare bedroom. we have had a little mould appearing at the bases of the affected walls and most of this is black, so maybe it is just a really bad case of condensation...

[lottie lou]

the way to solve this is to keep the room warm AND well ventilated. 

[norfolklass]

well, the man from the council is coming this afternoon so hopefully he'll know what the cause is. fingers crossed!

[betula]

Any news.I was just thinking how great it is to have all this helpful info :)