Damp

[rossage]

Hello! Can anyone offer some advice on dealing with some damp?

I live in a semi and the side of the house is damp (inside & out) from the ground up to about 300mm. The render outside has cracked so I chopped it all away to investigate. I discovered the old damp proof course in bits. (looks a bit like slate). I have also removed this and left the whole area to dry and now need to do something about it.

My questions are:

1/. Can I simply treat it with something then render over the top? If so what do i treat it with?

2/. How far down will I need to go?

3/. Any other pointers?

Any advice greatly appreciated.

Thanks!

 

[Softus]

From your description you have a fairly common problem where water has got behind the render and soaked the brickwork - aka penetrating damp.

Are you sure that you've removed enough render? It's easy to be mistake about this. The easy way to tell is take a solid metal object, like a cold chisel, and tap the whole of the suspect area, and beyond, listening for a change in tone. Where the render has separated from brick the tone will be sickeningly hollow - you might even feel it move. Where it's solid it feel solid and will ring out.

Hack off anything that's suspect - a garden spade is a good tool for levering off render, and it won't come off if it's firmly attached.

It's a good time of year for drying out, but even in the winter the wall would quickly dry once the water trap is gone. Then get a plasterer to repair the area. Render down to two courses above the DPC. For a neat finish get the plasterer to use a render stop bead.

Don't worry about the apparent state of the DPC - there's no such thing as rising damp.

 

[rossage]

Brillinat! thanks for that.

Am pretty handy with a trowel so will be having a bash myself. Just normal render mix ok? PVA or any other potions I should mix in?

How far down does the damp course normally go?

 

[Softus]

Am pretty handy with a trowel so will be having a bash myself. Just normal render mix ok? PVA or any other potions I should mix in?

Don't know - not my area - hopefully someone else will answer that one. I don't see why it would need to be an abnormal mix though.

How far down does the damp course normally go?

Eh? The DPC is horizontal.

 

[rossage]

yeah i know, but i thought a dpc starts below ground level and finishes around 200mm above ground level.

Not my area either... Am I being a ****?!

 

[dano1779]

you need to install a new dpc 6 inches above the outside ground level to allow for the splashback of rain and replaster inside and out using a waterproofer to youre render mix whice should be a ratio of 3.1

 

[rossage]

thanks for all replies...well appreciated!

 

[Softus]

yeah i know, but i thought a dpc starts below ground level and finishes around 200mm above ground level.

Not my area either... Am I being a ****?!

Well, a little bit yes.

The DPC is a thin (around 2mm) layer embedded between two specific courses of bricks, that is contiguous with the DPM (damp proof memrane) installed inside the house. Some older houses don't have a DPC, and/or a DPM.

Some people believe that the DPC prevents damp from rising through the brickwork, but this is a myth. All damp problems at the base of a wall are caused by water falling/dripping/trickling from above or water bouncing off ground that is too high and/or too hard and/or too near.

The minimum height for the DPC above exterior ground level is two brick courses == 100mm. More height will be needed if the ground is too hard if it can deflect rain onto the wall.

 

[dano1779]

work for a dampproof company and can tell you there is such thing as rising damp which is when your current damp corse breaks down or fails you need to install a new one which your best option is a chemical one. that is you're purpose of having a damp course to stop it rising

 

[Softus]

work for a dampproof company and can tell you there is such thing as rising damp which is when your current damp corse breaks down or fails you need to install a new one which your best option is a chemical one. that is you're purpose of having a damp course to stop it rising

Oh joy! The moment I've been waiting for!

Pray tell dano1779 - how many cases you personally seen where the DPC was replaced, with no other remedial work (other than internal replastering), with the result that a damp problem was cured?

If more than zero, can you supply any details of the property, e.g. address?

If you work for a damp-proofing company then do you have any customers who are happy to recommend your service? Any published testimonials?

Failing all of that, do you have any evidence whatsoever that rising damp exists?

I'm beside myself with excitement - it's like Christmas.

 

[dannythemole]

Ohhhh dang. what have I started...

 

[Softus]

Ohhhh dang. what have I started...

By doing what?

 

[dano1779]

work for a dampproof company and can tell you there is such thing as rising damp which is when your current damp corse breaks down or fails you need to install a new one which your best option is a chemical one. that is you're purpose of having a damp course to stop it rising

Oh joy! The moment I've been waiting for!

Pray tell dano1779 - how many cases you personally seen where the DPC was replaced, with no other remedial work (other than internal replastering), with the result that a damp problem was cured?

standerd practise is to install new damp course and take of the defected and contaminated plaster and reinstate and there has been cases where a new damp course has been installed and has dried out but it can be a long wait which is why its hacked off

 

[markie]

Talking about rising damp

 

[Softus]

Ohhhh dang. what have I started...

By doing what?

Talking about rising damp

But he didn't.