How to stop roots growing into our house and water ingress?

[lpr2468]

We moved into our house in 2019 and on 2 occasions since then our lounge room has flooded during heavy rain / cyclonic weather over 5 days. We really want to try and avoid this happening again! We think the rain comes in because right next to the house are 2 garden beds. Until recently, one of the garden beds had 3 camellia trees. It has taken us weeks to get to the stage in the photos as camellia roots are as hard as steel and they have grown into the brick wall and under the concrete. We think the best thing to do is to lay crusher dust, then sand then pebbles. However the concrete already down seems to cover half the weepholes for a short distance. Are we OK to go ahead with our plans for a pebble garden or should we take up the concrete which is half way up the weepholes? Should we seal the wall before filling with drainage gravel? How deep do we need to dig? 

 

 

[Dave-1]

Morning @lpr2468 

I would go as far as to use a piece of 50mm conduit and a hose down the center of the pipe as you push it under the path to cut away the soil below the path so the water has somewhere to drain to (into stormwater or a french drain type deal. 

I just had a look at what a drainage mat was  Strol 30mm 0.30m² SureSoak Drainage Cell and yeah I know what it is tho still think that plus an exit for the water to drain to would be a good idea, the mat to give free drain away and the pipe to take it elsewhere in the yard.

Dave

[TheHandySqirrel]

Hi @lpr2468,

in our case the issue was not as severe: A previous owner had raised a path next to our house and in the process bridged the damp proof course (DPC), allowing water to rise in the walls.

Check where your DPC is and if it might have been compromised. From the second photo it also looks like the mortar between the bricks might have leached out where it got wet.

In our case I added mortar to where it was missing, then applied two layers of bitumen paint (this one is water-based which makes easy tool cleaning) just below the DPC.

Good luck!

[lpr2468]

Can I ask a stupid question?  How do I know where the DPC is?

[JacobZ]

Hi @lpr2468,

Definitely not a stupid question as it is not exactly common knowledge.

They look like this when they are rolled up Cagroup 230mm x 30m x 500um Plascourse. Older versions may look slightly different, but you are basically looking along the horizontal mortar lines close to the ground for something that will appear as a line that is not mortar.

If you can see weepholes, it should be along the horizontal mortar line directly below them.

Let me know how you go. Happy to help further if required.

Jacob

[lpr2468]

Is it possible we have not got one? See the photo.

 

The house was built in 1983 in QLD. The pink chalk shows the weep hole layer. Below that it shows high on the moisture sensor....

[JacobZ]

Hi @lpr2468,

It's certainly possible, but the way the bricks stop being wet just below that course of bricks makes me think there is one there.

Could I trouble you to take a photo from lower down showing this particular mortar line?

There's a good chance this is where your dampcourse sits.

Jacob

[lpr2468]

Hi Jacob and thanks for your continuing support. I have taken some more photos. The lounge room wall is where the water comes in and we know the camellias have grown roots into this garden bed which we are still removing. We think the garage wall has no weep holes or dpc as it is just a brick wall. We have not had flooding in the garage.

 

 

 

 

 

[JacobZ]

Hi @lpr2468,

I can see some evidence of a damp course in your third and fourth photo.

Ensuring any natural earth or concrete that sits against the wall is at least 100mm below this level is going to be paramount to preventing further water ingress. If the soil or concrete is in contact with the bricks above this line, it can and will transfer up through the bricks and into the cavity behind the wall.

Digging down further to see what the roots have done is going to be important to understand what steps we need to take moving forward.

If you can expose the concrete below this garden bed, fill any obvious holes in the slab with a repair mortar and close up obvious seams where water could get in, you should be able to apply a below-grade waterproofing membrane such as this Crommelin Exterior Grade Brushable Waterproofer to help prevent further water from getting in.

If you can expose the concrete foundation and upload some photos, I will try to assist further.

Let me know what you think.

Jacob

[lpr2468]

Hi Jacob, we have found the dpc on the garage wall at the same level as the lounge room wall. I have concluded that some of this concrete needs to come up so we can level the paving 10cm under the dpc as there is no way around this. I am so annoyed that whoever laid this concrete has damaged my house. We are trying to figure out how much concrete we need to bring up to maintain the slope of 1cm per metre we need to run off the rain as the corner of the lounge is laid correctly 10cm under the weep holes. The pool fence is sunk into this concrete and it goes round half the house.😡 That is a lot more digging... a lot. I will put a string line to measure the slope once the concrete is up to check the level is right. 

[JacobZ]

Hi @lpr2468,

It's a huge pain, but at least you have a better understanding of the issue and a clearer plan of how to fix it.

Let me know if there are any other ways I can help.

Jacob