How to waterproof and repair a damp corner of the floor?

[ivanptr]

One corner of our house in our bedroom can get damp and moist when it rains. 

Only this corner so far. 

At first we thought its happens because the finished ground level of the yard is too high (higher than bedroom floor). But after we took out the soil lowering the ground level, the problem still persists.

Visually we do not see any brick wall cracks.

One mate told us, "even" the ground level was too high, theoretically the interior floor should not be damp and the problem is the vapor barriers of our concrete slab failed.

The problem is , we dont know how we should approach this and from which kind of professionals we should seek help first

We contacted waterproofing companies and they told us that :
May we also suggest that the plumber double check the fall and that the diameter of the drainage pipe is of adequate size. It would be good to have the pl;umber look at the rest of your property as you may need some additonal drainage system put in place.

1) There is only a rainwater drainage downpipe near that corner. No sanitary drainage pipe. And we installed a new downpipe to make sure there wont be water spilling out from the underground pipe.

2) We understand that upgrading the drainage system can help (There is an old AG drainage system alongside the house).

3) We regraded the side aisle of the house to make sure the water can flow away from that corner. But things only improved a little.

Isnt the first thing we need to do is directly addressing the problem : the leaking slab? 

We watched youtube and some companies applied the liquid rubber to the sides of the concrete slab, like this:

It seems much more effective and on point? If there are some "hairline" crack around the corner of the slab, put something to seal them seems to make more sense.

So complicated.
https://construemax.com/leaking-slab-foundation/
One useful link we found about this problem.

What are the most affordable way to solve this? Thank you in advance for any advice.

Any experienced members are specialized in this kind of issues? Really love to hear you thought. Thanks

[MitchellMc]

Hi @ivanptr,

I'd agree with the advice @EricL has provided.

On a side note, what was the waterproofing product they used? I can see the cement ledge they've created along the wall, but did they actually paint the wall with a waterproofing membrane?

Mitchell

[ivanptr]

 @TedBear, yes, its a saga we have been through 😅. So far its difficult to tell because the rainy season has been passed in QLD. This week the weather has been too good. we are now waiting for a downpour ! haha

One thing we must say first how we find this workshop forum valuable to us. Without you guys, we wouldn't know a thing about all the concepts and ideas - how to diagnose and investigate , what material / process needed to fix the issue, what possible cause for a little water ingress.

Even though the plumber only completed 90% of work this time, we are glad that when I first met the plumber, I could specify clearly what I want to do.

If we don't know a thing, and fully authorized the tradies to do anything they say is good, the situation "could hv been" worse. 🤣

@EricL, Yes, we mentioned 3 times that we want the corner waterproofed by Email , not just along the aggi drain, and also that small session. And we even attached a photo highlighting that corner. Their email response were positive. We have all the email record, but i guess we will do it ourselves. Fortunately its only a small section they "missed". Too much effort to bring the issue to Fair Trade.

Next project we we will manage better, some valuable lessons we learnt : 

1) Weather: when it is related to external waterproofing, try to book the work after rainy season, as we rescheduled the work several times due to bad weather. 

2) Specific: Another great lesson learnt from @MitchellMc!! need to be specific , next time if meet tradies for quotes, we could ask what waterproofing material they will use , and then have this specified on the quote.

3) Onsite: On the work day, I wasn't onsite and only my old parents were home. This was a big mistake. If I were there, I could immediately raise the issue to the tradies. 

Hope any new renovator/ house owners reading this will learn from our lessons!!!

Love you guys! many thanks

[EricL]

Hi @ivanptr, 

I'm glad you've made a decision with the waterproofing. I'm sure your D.I.Y. journey will be very useful to our members who are planning on waterproofing the exterior of their house.

Please keep us updated with your progress, we look forward to seeing all your waterproofing complete.

Eric

[Adam_W]

Hi @ivanptr, looks like I joined the chat too late but you've done some fantastic research, prep work & follow-up DIY yourself, well done & also to the great advice others have given.
Water issues are always so difficult. We're taught from an early age that 'water always runs downhill...' but the more you deal with it the more you find it seems to defy every law of physics at times.
From a brief reading of your issues I think the two problems are unrelated but the leaking gutter may have been exaggerating problems in that corner by introducing more water to the soil in that corner. The leak may also have been saturating the brickwork leading to some moisture penetration in that corner.
Moisture can rise up through slabs and walls when membranes have failed and realistically the best way to deal with this is to seal whatever is possible but also remove as much water as possible from the area.
Sounds like things are working for you now so keep us all in the loop!

[ivanptr]

Hi everyone, 

The plumber we hired only built an agdrain channel from the corner of our house. Shorter than we what we agreed upon. It should be longer aligning with the retaining wall We have learnt a lesson about how we should make it clear on the quote. 

 

And because of the water table, under ground water is still flowing from the neighbors higher ground to our bedroom.

 

Its a bit of frustration. But we wont give in.

So now, we are planning to make an agdrain channel to keep the rainwater from coming in:

Agdrain -＞attached to a drainage pit -＞ then through a pvc pipe

2) For measurement of concrete humidity, what is the best way ?

We are getting contradicting signals from different methods-

Moisture meter: whenever it touches upon any concrete the reading reaches 90%, we selected masonary in the setting

Plastic bag : visually NO moisture trapped 

Rust and mould : not quite relevant, since they have been around long before we moved in. And since moved in, we hv already fixed : broken downpipe outside the bedroom + installed a ag drain. 

So we want to know if things have been improved after our projects.

Carpet : This is the most mysterious sign we just dont understand,  the carpet was occasionally wet . And yet , if plastic bag on the concrete didnt trap any water...

3) We are going to dump this old and dirty carpet and replace it with vinyl plank. Is it a good idea? Seems the carpet can faciliate mould growth easier than plank.

Lastly, many thanks for any advice and thought, or ideas. We will keep fighting until this problem get solved.

 

[EricL]

Hello @ivanptr

My vote goes to the traditional moisture indicator the plastic bag. It will always show you if there is any hint of moisture as the plastic will have water droplets trapped on the surface. If you decide to use vinyl plank make sure that it is the waterproof type or as they call it the hybrid type. A good example is the HanWood Home 5mm 2.64sqm Capella Oak Hybrid Waterproof Flooring. This 100% waterproof flooring solution can be installed in high moisture areas including kitchens, laundries and bathrooms.

Let me call on our experienced members @Vis-á-vis and @Adam_W for their recommendations.

If you need further assistance, please let us know.

Eric

[ivanptr]

Thanks so much Eric,

Its a relief to hear your vote goes to traditional plastic bag approach.

Then , the situation might not be as bad as we think.

The moisture on carpet might be due to condensation and indoor humidity.

Ok, the Hanwood planks will be on our to buy list. And today we will remove the whole carpet. 

And stick more plastic bags on the whole concrete floor, to make sure the mositure did not come from the concrete.

Do u hv any tips on how to get the rusted carpet nail out? We used a prybar but ended up taking out some bits of concrete out , as well.  Not too good.

We are thinking to use angle grinder to grind the nail head. Any good ideas?

 

[MitchellMc]

Using an angle grinder sounds like the most effective method @ivanptr. I'd then be inclined to pick up a can of Zinnser B.I.N Primer Sealer Stain Blocker and apply a squirt over the remains of the rusty nails. This should stop any rust stains from bleeding through into your new flooring. I wouldn't expect that to happen, but better safe than sorry.

Mitchell

[Vis-á-vis]

Hi Ivan,

So much information here and have not had time to read it thoroughly but get the general idea of your ongoing issues. Below is some general information that you may or may not already be aware of. A decent waterproofing professional should be able to unpack your specific problem and offer a solution.

1. With any water ingress it is always best practice to deal with it from the positive side. In your circumstance that is outside.

2. Aim to drain as much water away from the area as possible.

- I can see you have already attempted this and the drainage looks to be in a good position - away from and slightly below the strip footing.

- Personally, I would never use flexible Agi pipe as it is prone to silt build-up and clogging which is very difficult to clear in later years. I would always use solid pvc pipe with slots cut underneath and an inspection/cleaning upright (at 45ish degrees) finishing above ground level so you can clean that pipe out later without excavating.

- Above that drainage pipe should be free-flowing aggregate - scoria or similar - and ideally a crushed rock/pebble/concrete overlay.

3. If you have earth or aggregate up against an exterior wall that is higher than your interior finished floor level you MUST have a waterpoof barrier in the form of a liquid or sheet membrane system to stop lateral damp.

4. If you have earth up against an exterior wall that is lower than your interior finished floor level then you need a damp course either installed in the brickwork or retrofitted in the lowest possible course above the earth level outside.

5. Even having done all of this you can have residual moisture in your walls that can take many months to disappear. This is what you may now be experiencing. 

6. If you have moisture (but not running water) entering through masonry or concrete on the interior then you can stop this by applying a two-part epoxy vapour barrier. Products I use are Gripset E60, Ardex WPM 300 and Fosroc Nitoproof 310 which are all excellent products but must be applied carefully and with some knowledge/experience.

7. If you have more than moisture (rising water) entering via a concrete slab then really the only option is to inject either hydrophilic or hydrophobic (dependent on the exact situation) to fill any voids within and/or under the slab. Again, a decent waterproofing professional should be able to advise.

8. Not wanting to rain on your technology but the moisture meter you have is completely useless for what you are trying to achieve. It will not give you an accurate indication of moisture in concrete and only a very very rough idea of moisture in timber. In my job, I use a couple of moisture meters, the two of them are close to $3000, and still struggle with certain situations. For example, my Tramex X5 is specifically designed for concrete but can only measure to around 7% moisture so anything above this is basically measured at 100%. What you are using will only mislead you.

Feel free to ask any specific questions.

[EricL]

Hi @Vis-á-vis

Thank you so much for that in-depth list of recommendations. Let me tag @ivanptr to make sure they are aware of your suggestions. Water ingress I think it's one of the hardest things to fix. Especially if it has not been repaired for many years. Moisture is now heavily embedded into the masonry wall and floor and will take quite a while for it to all go away.

Eric