Damp suddenly appeared..

[ryoc]

I have noticed that in the void beneath our floor, next to the garage wall and below the dpc, damp is coming through the brickwork. This area has previously been dry..There are no leaking pipes etc. It's a long shot, but any ideas? Thanks

 

[whistler]

Are there any drains nearby?

A damaged drain pipe could be leaking water into the ground and if this is below your damp course the water will eventually begin to soak up into the brickwork.

Fortunatley this will stop at the damp course, but if left unattended could damage your foundations.

How do i know? I've just discovered my toilet drain has been leaking into the ground. Don't know how long for, but am waiting for the drain inspector to come and survey the problem.

 

[ryoc]

Thanks for the reply. I will check the drains nearby..

 

[whistler]

CCTV camera went up the drain from the manhole to the toilet and there are in fact two leaking joints between sections of pipe. On one of them the flange (if that the right word) has broken off.

Now its a man and shovel job to dig out and replace the faulty sections.

Just for good measure he sent the camera in the other direction towards the main drain and found water in there which suggest the drain has sunk. They are going to try and line this with a new pipe inside the old one.

 

[Softus]

...the water will eventually begin to soak up into the brickwork.

This is rather fanciful - by what means do you expect water to rise within the brickwork?

Have you ever seen such a thing happen?

 

[^woody^]

By capillary action through the brick and mortar

 

[Softus]

Come into my parlour then ^woody^...

Have you personally seen this happen - this capillary action through brick and mortar?

 

[^woody^]

Yes, moisture rises (and moves horizontally) by capillary action, which depends on the spacing and size of pores within the mortar and brick or block. The denser the brick, or the fewer the voids or pores in the mortar then the less chance of moisture moving far via capillary action. But unless the material is truly waterproof - eg a plastic DPC, then there will always be some movement of water.

I've seen it countless times. Whether this is the problem here is another matter.

To quote from BRE 466 - Understanding Dampness - "Water moves into or through a wall under the action of several forces including capillary action, diffusion, wind, gravity and sorption."

 

[Softus]

I've seen it countless times.

Really? In that case, please tell me more about just one of these countless instances of damp rising through brickwork.

To quote from BRE 466 - Understanding Dampness - "Water moves into or through a wall under the action of several forces including capillary action, diffusion, wind, gravity and sorption."

I see - "into", or "through", but not "up".

 

[anobium]

Softus, see definition of capillary action

Capillary action or capillarity (also known as capillary motion) is the ability of a substance (the standard reference is a to a tube in plants but can be seen readily with porous paper) to draw a liquid upwards against the force of gravity. It occurs when the adhesive intermolecular forces between the liquid and a solid are stronger than the cohesive intermolecular forces within the liquid. The effect causes a concave meniscus to form where the liquid is in contact with a vertical surface. The same effect is what causes porous materials to soak up liquids.

A common apparatus used to demonstrate capillary action is the capillary tube. When the lower end of a vertical glass tube is placed in a liquid such as water, a concave meniscus forms. Surface tension pulls the liquid column up until there is a sufficient weight of liquid for gravitational forces to overcome the intermolecular forces. The weight of the liquid column is proportional to the square of the tube's diameter, but the contact area between the liquid and the tube is proportional only to the diameter of the tube, so a narrow tube will draw a liquid column higher than a wide tube. For example, a glass capillary tube 0.5 mm in diameter will lift a theoretical 2.8 cm column of water. Actual observations show shorter total distances.

With some pairs of materials, such as mercury and glass, the interatomic forces within the liquid exceed those between the solid and the liquid, so a convex meniscus forms and capillary action works in reverse

Round 2.!

+++++++++++++++++
I hope we're not going to replicate the "Rising Damp
is a figment of the imagination" thread here.

Just let someone answer this person's question, and the obsessives can shout at each other on the other side of the playground.

Mod Rupert
++++++++++++++++

 

[^woody^]

With a cavity wall, mortar snots on the tie wires can lead to moisture crossing the cavity to the inside leaf.
This movement is caused by capillary action

 

[anobium]

+++++++++++++++++
I hope we're not going to replicate the "Rising Damp
is a figment of the imagination" thread here.

Just let someone answer this person's question, and the obsessives can shout at each other on the other side of the playground.

Sorry mod I didn't start it he did, I was merely pointing out to Softus that he was incorrect in saying to ^woody ^ that there was no reference to the upward movement of moisture in the article referred to.

With a cavity wall, mortar snots on the tie wires can lead to moisture crossing the cavity to the inside leaf.
This movement is caused by capillary action

I've got to disagree with you on this point ^woody^, this is the lateral movement of moisture, and nothing to do with capillarity.

 

[^woody^]

Lateral movement by capillarity?

Its probably down to semantics - one persons capillarily action is anothers diffusion and anothers absorption.

However, although each method can be defined, to the homeowner the end result is often the same

 

[Softus]

+++++++++++++++++
I hope we're not going to replicate the "Rising Damp
is a figment of the imagination" thread here.

Just let someone answer this person's question, and the obsessives can shout at each other on the other side of the playground.

++++++++++++++++

Way to set an example, Mod Rupert - your post is both personal and abusive.

You will not be missed when you go.

 

[Softus]

With a cavity wall, mortar snots on the tie wires can lead to moisture crossing the cavity to the inside leaf.
This movement is caused by capillary action

Again - is this a theory that you've read about, or have you actually seen an example of damp rising through brickwork?

If the latter, then please do tell me all about it, because I've scoured the country for you. I came through time for you, ^woody^.