Can I plug damp proof rods into brick?

[Zach R]

Hi,

I've bought a 1930's semi in Surrey, we've got rising damp. The house has pebbledash rendering, I can see a few previous holes drilled through the render for a damp proof course, so I can use those again, but they only go around half the house. They must have been drilled after the pebbledash application.

I'm wondering, can I follow that line and drill the rest of the holes without removing the render to insert the dry rods? Good chance some will go into the brickwork and not the joint..

How effective will the DPC be if some rods are in the brick itself?

Many thanks in advance

 

[Larry1990]

Is there not an exposed mortar course lower than where your render ends that you can drill into?

They will be useless if they are not lower than the level of your render as damp can effectively bypass them.

If your render is to the ground level then this is wrong.

You will hopefully get some good advice soon from the knowledgeable folks here about ruling out other common causes first.

 

[Zach R]

I'll post a few pics tomorrow

 

[JohnD]

Yes but they don't work.

If your house was built in the 1930s in England it will have been built with a DPC, most likely slate but might be bitumen. Can you see it? Look carefully under and beside doorsteps. Slate does not wear out.

Post some pics of your damp walls, from ground and up two feet. Indicate the position of the DPC, for example with a chalk line

Inside and out

Do you have solid floors, or wooden with a ventilated void beneath?

Draw a floorplan of your house, showing the position of the damp patches, the indoor and the outdoor stopcocks, and the drains, gullies and manholes

 

[JohnD]

we've got rising damp

Rising damp is a myth, says former RICS chief

Stephen Boniface, former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS), has told the institute’s 40,000 members that ‘true rising damp’ is a myth and chemically injected damp-proof courses (DPC) are ‘a complete waste of money’.

www.architectsjournal.co.uk

 

[Zach R]

Just to add some extra context, the ground outside the front was quite high and the previous owner had a raised planter around the front and side of the house, there was soil against the house above the DPC, and 2 of the vents were covered up. Some of the plants had grown onto the wall pulling off render and exposing brick. That's about the spot where we have damp in the one room, the other room, the outside gully was completely blocked and water was getting into the brickwork there. That's the other damp room.

Alls been sorted now as I've lowered the drive, added a channel drain and fixed the gully, this was about a month ago, so I guess the walls haven't really had a chance to dry yet..

Where the render has blown, I intent to rerender once the walls have had a good chance to dry around June time.

My thinking was, I may as well chuck DPC rods around the house while I'm at it...

Do you think I just leave walls to dry, then rerender without using dry rods?

Just loaded some pics there. You can see how high the soil used to be. You can also see (what I assume to be) the old holes from previous DPC above the black painted brick

FYI. Only sign if inside damp after 4 months is slight blistering of paint in 1 room. Nit much sign at all but the damp was picked up in the hone buyers report so want to get ahead of it

 

[Zach R]

These are the before pics. Put old tiles between planter and wall to stop rain getting in. That planter was full of soil

 

[jeds]

Where the render has blown, I intent to rerender once the walls have had a good chance to dry around June time. Yes, but I would hack off any bad render now and leave it exposed. Ideally take the render off to somewhere above the dpc and then re-render with a bell-cast bead about 10mm above the dpc. The area below the bell-cast can be rendered with a thin coat mix and painted later with a bitumen type paint.

My thinking was, I may as well chuck DPC rods around the house while I'm at it... I wouldn't bother. Waste of time and money.

Do you think I just leave walls to dry, then rerender without using dry rods? Yes.

You might also have to look at the internal plaster. When walls are wet for prolonged periods of time, the internal plaster, and masonry, will become contaminated with salts and this leads to almost perpetual apparent dampness. I say apparent - it looks like dampness but is actually moisture absorbed from the atmosphere.

 

[tell80]

OP,
Pics showing suspect interior wall surfaces will help?
And pics showing inside the planter bed with some of the tiles removed will also help?
FWIW: the tiles are useless & might even begin to cause splash problems higher up the render - best to remove the planter wall and the tiles.
Can you point out where your DPC is?

The ground level is still too high - air bricks are installed in the joist bays so its probable that any joist tails that are sitting in the wall are affected by damp - you should investigate under the floor.
The black paint appears to be on a scratch coat of render.
Previous render repairs can be seen - where is the render blown?
Are the walls solid wall or cavity wall?
The render is in ground contact - there should be a gap between the render and the ground.
The property is located downhill so you will experience high ground water.

 

[Zach R]

The planter was removed, we lowered and paved the front and added a channel drain. I've loaded a few pics of what it looks like after. Attached internal pics too. This is the only internal sign of damp. Just a bit of paint blistering. The other room has no visible issues

 

[JohnD]

Have you been able to find the original DPC yet?

This is very important.

And yes, there is one.

You will need to chip off that black painted plinth.

It was generally applied in a futile attempt to hide (it does not cure) a wet wall. What it does is provide a path for water to rise by capillary action up the render beneath and the black paint prevents it from evaporating off the surface and drying out.

 

[Zach R]

I haven't found it, haven't looked yet to be fair I assumed that it would be at the point the black plinth meets the render... I'll have a look for it and post back here. Thanks for the advice!

 

[Nige F]

That's a fair assumption re: the DPC

 

[jeds]

The planter was removed, we lowered and paved the front and added a channel drain. I've loaded a few pics of what it looks like after. Attached internal pics too. This is the only internal sign of damp. Just a bit of paint blistering. The other room has no visible issues

You've done everything correctly so far. Just a question now of when/how to repair render - see my post above - and deal with anything internally if necessary.

 

[tell80]

OP,
I noticed the pics you posted in posts #6 & #7 before I replied in my post #9 - what I said in that post still stands - the after pics shows much that needs correcting - you have not "done every thing correctly so far" far from it.

I also asked some questions? Questions are meant to help you. Perhaps OP you will answer them?

Its claimed in post # 8 that: "The area below the bell-cast can be rendered with a thin coat ... etc."
No it cant - you would bridge the DPC - and what would be the purpose of the bell-cast if you render below it?

Post #15 claims: you only have to "deal with anything interior if necessary."
"if necessary" - the interior pic shows damage from damp activity that must be dealt with - we have no knowledge of its extent or its cause - answers to my questions might help to say why?