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How to fix water in a cavity wall?

Hi troop,

We recently had the wall between a bedroom and its dressing room opened up (our son didnt require 4m of hanging space!!!) - and concerningly, found deepish water inside the cavity wall.

The house is on a slope. The bedroom subfloor (rock) is permanantly wet with little puddles.

The diagram shows all the relevant info - what would you do to solve this?

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JacobZ

Hi @lisyloo725,

Thank you for your question about the water you've found in a cavity after removing an internal wall.

I'm happy to offer advice, however, it is unlikely that this is going to be an easy fix or even one that is possible without the assistance of a builder or foundations expert.

The fact you have said the subfloor in the bedroom is permanently wet makes me believe there are some major issues.

Are you able to upload some photos of the cavity, the subfloor and the outside of the house? This would certainly help our members offer their best advice based on your situation.

Allow me to tag some of our knowledgeable members to see if they have any thoughts, @Nailbag, @Jewelleryrescue, @Dave-1, @TedBear.

Let me know if you have any other questions.

Jacob

Nailbag

Hi @lisyloo725

I guess my first question would be is the bedroom of concern part off the original hime, or is it a conversion from a non-living space to a living one? the reason I ask is that its quite common to make these conversions without any proper building plans and approvals resulting in these types of scenarios. In which case I would be taking the advice of @JacobZ and have a registered builder or draftsperson inspect the property to see what if anything can resolve the issue. It won't be an easy one to solve as any sub-level spaces not designed to be one, usually requires escavation before waterproofing can be applied.

Nailbag

Dave-1

Morning @lisyloo725

Im in agreement that it would be an idea to get some professional people in to have a look and suggest ways forward.

The standing water concerns me for a couple of reasons,

Where it comes from (yes a trench and a differenat drainage solution can help with that)

The subfloor somehow holding back the water in the base of that wall.

Are the existing timbers rotting?

Does the area under the rest of the subfloor have any water in it as well?

Is there any sign of water in the garden store area? And what is its floor made up of?

More investigation would help with narrowing down the options you have for going forward.

Dave

lisyloo725

https://www.workshop.bunnings.com.au/discussion/comment/41858#Comment_41858

Hi JacobZ - thanks for your reply

Here's a photo of the subfloor.

We have put a pipe into the cavity wall to drain it

And have used an angle grinder to guide any water under the bedroom towards an exit too.

Just so you can find your way around, the top of the picture is where the water-filled cavity wall is. Right of the picture is the side wall of our house, so we can drain to there.

lisyloo725

https://www.workshop.bunnings.com.au/discussion/comment/83126#Comment_83126

This is the wall between the bedroom and walk-in wardrobe being removed recently. The problem cavity wall is at the bottom there - the yellow ended prop is touching 'problem wall' (as we call it!!)

lisyloo725

https://www.workshop.bunnings.com.au/discussion/comment/41870#Comment_41870

You guessed it - the walk in wardrobe is an add on. To be honest, the whole of this floor, under the original house, is probably an add on. I'd like to actually get some original plans for the house - do you know where I get those from? Council?

We've actually done a whole load of excavation - we've done an AGI drain across the front of the house (the uphill) - about 1m away from the front of the house.

We've also dug away the soil that abutts the house at the front (uphill side), and applied DRYZORO to the brickwork, down to the footings, and coming up 2 brick courses above the DPC. We will put an agi drain there, and blue metal gravel.

We've done the same along the side of the house - a full length trench, DRYZORO Same going here - megaflo agi drain, and blue metal gravel.

The fake grass is just to stop the soil falling in

We have made the trench at the side carefully fall in gradient - we've used concrete (plus dryzoro) to smooth out any dips.

lisyloo725

https://www.workshop.bunnings.com.au/discussion/comment/41896#Comment_41896

Thanks Dave - we just bought the house, and budget really doesn't allow for professional help sadly.

The timbers are actually in good condition.

The hallway to this room and the bedroom next door had timber joists that needed replacing - but bone dry floors.

The garden store floor is just soil - so we can dig there. I think we'll come to water once we get to the same level as we found water in the cavity wall. Do you think it's just the level of the water table??

Since my first post, we've been busy slicing viewing holes the size of a A2 sheet of paper out of the nice concrete base of the dressing room and digging down - we've found water about 70cm down in all of these.

Our current plan is to check out an old ceramic drain pipe that cuts across the house at about this position (we can see one end of it in our garage...so we're going to buy a drain inspection camera to take a look in the pipe.

It' been fed water from a leaky carport for some time (which we have fixed) - but we fear the water has been trapped and had nowhere to go...

I'll update

Many thanks alll - so far!! 🙂

lisyloo725

https://www.workshop.bunnings.com.au/discussion/comment/83128#Comment_83128

The pink lines are the trenches we have dug. Where next to a wall we have done dryzoro.

The blue circles represent the viewing holes we've done with an angle grinder in the concrete base for the dressing room. Water below each.

The problem cavity wall is between the dressing robe and bedroom 3.

The green circle shows the location of an old ceramic drain we have found and we can see it curves in the direction of the arrow.

As I said above - we think this might be a good next step to investigate - as it was previously receiving water from the leaky carport (above the workshop and store). Maybe it is broken and the water it was carrying has just spilled out under the middle of our house for years.

Any and all suggestions for next steps welcomed!! Funds don't allow for professional help sadly.

lisyloo725

https://www.workshop.bunnings.com.au/discussion/comment/106420#Comment_106420

Sorry - one last thing - we are wondering whether we should install a SUMPUMP - wondering if anyone has any views on that/recommendations for one that might be a good option for us - and where it would be good to site it.

Thanks so much all!!!!

EricL

https://www.workshop.bunnings.com.au/discussion/comment/120390#Comment_120390

Hello @lisyloo725

I would only recommend a sump pump if it becomes impossible to find the location of where the water is coming from. If the water comes in very large torrents during a heavy downpour, then it would be safe to have a sump pump installed in a very large pit under the house. It's not an ideal solution, but it's better than flooding the bottom of the house. I propose looking at the Ozito 500W Vortex Submersible Sump Pump as a possible candidate should you decide to install a sump pit.

If you need further assistance, please let us know.

Eric

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/128992#Comment_128992

Morning @lisyloo725

Woooo you guys have done loads of work! And I really get your frustration.

I would have and have done similar to you in removing the possibilities of water endtering via your trenches and ag pipe. (Does water flow out of them at all?)

I think that there is a water table from your description, So a question. Does the water level rise or can yous ee water traveling in any direction?

I would also head towards a sump pump, tho not ideal. I would be tempted to chanel the water so the sump pump is outside the building. The floor likes like stone/shale? Mainly because if there is an issue you can see and also replace the pump easily. Any water left under the house will cause issues 😕

It sounds like an intense but way interesting project. @EricL's mention of rain and inundation could be measuered against the amount and flow over a week or so after a rain event? Will keep thinking about it and get back to you if I think of something else. 🙂

Dave

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