Rising damp below kitchen sink

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Old 12-11-13, 10:09 PM
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Rising damp below kitchen sink

Hi All,

I wondered if anyone might have insight into something i've noticed in my recently bought house. Below the kitchen sink their is a semi-circular damp spot raising from the floor (base of cupboards).

The dampness is not very wet, only slightly cooler than the cupboard wall above it. The dampness does not seem to be growing and extending past where i first noticed it.

Originally i thought the dampness might have come from the pipe leading to the outside tap. Winter just hit and i was worried i hadn't turned the water off to the outside tap. However i checked and i did turn it off. I did notice that the hose attached to the outside tap froze and water frozen ice extended out the house. However i believe this is normal.

I don't see anyway of diagnosing this short of cutting into the cupboard to see what's below the damp spot.

I know that behind the kitchen cupboards is an old window which has been sealed in. It appears to have been sealed quite dodgily as the outside part of the window is sealed with some 18 mm plywood (I hope there's something more behind that!). I guess water could wick in through this plywood and then up the cupboard wall.

Perhaps i just need to call a plumber

I guess my main question should be, should i be concerned by a damp spot that doesn't grow in size?

cheers
oman
 
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  #2  
Old 12-12-13, 08:36 AM
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If you have an outside spigot near there and a hose was attached during freezing weather it is very possible the pipe in the wall has burst and it's a good place to start looking. Worst would be if the interior shutoff valve was closed and the hose outside was attached and full of water. Also bad is if the outside spigot is closed with water trapped between it and the closed interior shutoff valve.

Quite often things can freeze without damage. Worst is when freezing water is trapped. Water is it's greatest volume/size right before it turns solid. An ice plug on one end and a closed valve on the other leaves nowhere for the pressure of the expanding water to go. Water is basically not compressible so it puts tremendous pressure on the piping which is often the weak link.

Before freezing weather you MUST remove the hose from the spigot. Best would be to drain the water from the hose for storage but... Close the interior shutoff valve. Then open the outside spigot and leave it open. This will let the water trapped between the two valves drain out. Leaving the outside spigot open during winter allows water to escape if the interior valve leaks or if there is any misc water left inside it will eventually evaporate away.

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There is a leak or water was spilled somewhere and you need to find out where. The problem will only get worse so do not put it off thinking it's only minor. Now it's just a leaky pipe to fix. Wait and the cabinet particle board will break down and fall apart. Wait longer and you can have structural problems as the framing of the house rots.
 
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Old 12-14-13, 08:17 PM
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Thanks Pilot for the detailed reply.

I had worried this might have been an issue, you are right that there was a hose left attached to the tap. The interior shut off valve was closed but the outside valve was also left close. We had only just bought the house and i remembered to turn the shut off valve off but didn't have a chance to remove the hose before the weather dropped below zero (we hadn't moved in yet).

When the weather froze, frozen water was seen coming out of the hose.

I've just now opened the outside valve for the hose. I'm assuming i should remove the hose now as well.

I did check the interior shut off valve and there's no sign of dampness here or burst pipes.

I did investigate the location of the leak and it lines up exactly with an old window which was removed and boarded up with 18 mm plywood. I did have a theory that moisture was wicked in through this window.

Anyway it sounds like i need to get a plumber in to double check i haven't burst any pipes.

thanks
oman
 
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Old 12-15-13, 04:40 AM
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I have seen pipes get tiny little pin holes or cracks that can spray water up in a fine mist. If you're not finding water below the spigot pipe I would suspect the old window. It's quite possible that wind drove rain against the side of the house where it got behind the plywood and ran down inside the wall.
 
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