Moisture ingress in below ground living area

[John the builder]

Incondo
the comment on waterproof concrete was in respect to water getting to rebars?

You didnt address internal specialist coating solutions?

[Merlot Mike]

Any opinions on liquid coatings vs torch-on type membranes for the external waterproofing?

[Incodo]

John: The action of water into rebar is complex but in a nutshell a) unless the problem building is in the corrosion zone ie right by the sea the rate of deterioration will be exceptionally slow. Rebar is protected by the alkalinity of concrete. This is lost over time by a process called carbonitation whne concrete gets wet and dry repeatedly over years, becomes brittle, loses strength and it's pH drops. That leads to corrosion and as the rebar swells it blows the concrete off such as you see on old wharfs. Protection has to come from the outer face, but being wet in itself doesn't cause corrosion - that's why concrete piles under water often perform better than the structure that gets wet and dry that they support
Merlot MIke: Sheet coating are usually thicker and inclined to last longer than liquid. If you want authoritative independent info relevant to NZ Google -Grayson Wagner membrane NZIA- and look for the free paper. Torchdowns tear and currently there are about 30 on the market imported from reputable and less so manufactuers and some are in my view rubbish, we've even found roof grade ones that rotted within 7 years. They are OK on roofs but hugely dependant on the applicator's skill. I prefer the peel and stick polythene faced modified bitumen types. Key reason is that laps seal so much better than welded or glued joints, and as mentioned they sort of self seal if cut Many feel butyl rubber and EDPM have had their day and tougher TPO type materials are finding favour. Liquid membrane performance over time is usually proportional to the thickness and that's related to cost. It may be only as effective as the thinnest and worst bit of application.
Regards
Incodo 0272800036

[Incodo]

HI John the builder
Sorry re Internal specialist coatings
The risk with water coming into a basement is that it can be driven under pressure - hydrostatic head effect. In winter as the ground water levels tend to rise pressure increases and can blow surface applied coatings off the wall. Sure you've seen blisters with efflorescent salts under them. The liquids only have a limited ability to bridge cracks - they may be OK for bridging existing cracks but inevitably will have less ability to bridge new cracks. For the same reason sheet internal membranes are a non-no and even more so.
Crystalline grouts can penetrate 12-16 mm from the external face but work best on monolithic materials such as concrete, but they only penetrate a couple of mm when applied on a wet inside face. Our experience is that they can slow water entry or move the point of ingress just to the side of where the application stopped. Bit like the boy plugging the dyke. Fix it one place and it comes in another.
Given this job that started this thread is concrete block I'd still suggest a) remove the gib to take a look b) check the filed drain is clear c) bite the bullet and do the outside once and well
Regards
Incodo 0272800036

[Merlot Mike]

Merlot MIke: Sheet coating are usually thicker and inclined to last longer than liquid. If you want authoritative independent info relevant to NZ Google -Grayson Wagner membrane NZIA- and look for the free paper. Torchdowns tear and currently there are about 30 on the market imported from reputable and less so manufactuers and some are in my view rubbish, we've even found roof grade ones that rotted within 7 years. They are OK on roofs but hugely dependant on the applicator's skill. I prefer the peel and stick polythene faced modified bitumen types. Key reason is that laps seal so much better than welded or glued joints, and as mentioned they sort of self seal if cut Many feel butyl rubber and EDPM have had their day and tougher TPO type materials are finding favour. Liquid membrane performance over time is usually proportional to the thickness and that's related to cost. It may be only as effective as the thinnest and worst bit of application.
Regards
Incodo 0272800036

Excellent info. Are the bentonite membranes (aka Swelltite) different again from the above mentioned types?

[Incodo]

Hi MIke - The clay type membranes concern me as a) they can easily get damaged in installation and there goes your waterproofing (invariably in some position you can't easily access from the outside) and b) they seem to lack the ability to retain integrity over high movement areas such as between columns and tilt slabs or concrete block infills.
Just been asked to review consent drawings for a 2 mil job and note they are using brush on bitumen as the tanking material. LAMs ( liquid applied membranes) are only as good as the applicator who unfortunately will be the labourer who hates the dirty job.
And of course every tanking product technical expert is a salesperson and they all always only sell the best eh ? Something to be said for getting independent advice. The free specification offered by many paint and membrane applicators - well there is no such thing as a free lunch
Essentially my preference is something thick, tough as, waterproof under real tests and also sticks to walls and itself like crazy. Why do less given the risk
regards

Paul at Incodo

[Merlot Mike]

Essentially my preference is something thick, tough as, waterproof under real tests and also sticks to walls and itself like crazy. Why do less given the risk
regards

Paul at Incodo

I see you're based in Tauranga which is a shame as I would book you for a consultation if you were in Auckland. Which company/installer can you recommend up here?

[mrsaneperson]

Thanks Paul at Incodo for sharing your specialist knowledge . much appreciated.

Ardex Hydrapoxy 300 i guess is still not a 100% bullet proof coating solution?

[Incodo]

Merlot Mike: Sorry we don't to recommend companies for work but the type of material we prefer trade under names like Bituthene and Protectowrap and their are others with equally good very similar products. We work NZ wide, mostly commercial / institutional and stick to investigative only.
Mrsaneperson: When you look at the tech sheet for the material it states 300 micron wet film application but its water based and solids percentage is 44% so after water has dried off film thickness is 132 microns or 0.13 mm. However the materials we prefer are 1.5 mm i.e 10+ times thicker - gotta be good for you For wall tanking a decent area, the fact that a) the surface for modified bitumen sheet does not have to be flushed as perfectly as for a LAM b) you're only applying a primer and then single coat c) plus performance advantages discussed earlier .....

Hey being a newbie on this forum - observation - lot of discussion on rentals, markets, etc but not much on property physical issues and relatively little on legislative requirements, PCBU. BC, PM obligations or Court eg Blackdog claim, HCC v Alura, Crafer Crouch case, etc.
Regards
Paul at Incodo 0272800036

[mrsaneperson]

Thanks for the reply back.

I think in my situation the council recently improved the stormwater capacity as the drains nearby were always flooding in the event of a heavy storm I'm guessing that would help reduce the water table as well and bring down the hyrostatic pressure sitting behind the breeze blocks.

[Merlot Mike]

Hey being a newbie on this forum - observation - lot of discussion on rentals, markets, etc but not much on property physical issues and relatively little on legislative requirements, PCBU. BC, PM obligations or Court eg Blackdog claim, HCC v Alura, Crafer Crouch case, etc.
Regards
Paul at Incodo 0272800036

I agree... I too am a fan of Building Science.

[Merlot Mike]

What's interesting is that despite all of the differing opinions on these myriad waterproofing systems I see that many are "BRANZ approved"... I wonder what that tells us.

[GLin]

Like many have said already, inside waterproofing is not bullet proof, water is still trapped inside the blocks, and will find a way to seep out in other places.

Best solution is a combination of both exterior excavation, exterior membrane, exterior toe plus surface drainage, and inside waterproofing.

[Incodo]

HI Mike Merlot
Ummm I think you'll find BRANZ don't "approve" products they issue "Appraisals" and they're not warranties
Check the Conditions of Appraisal at the end of a recent one (eg No 447) . "BRANZ makes no representation or warranty as to - any guarantee or warranty offered by James Hardie. BRANZ provides no certification, guarantee, indemnity or warranty to James Hardie or any third party.
Arguably a Codemark is better backing but the certification industry - well some feel it should be mre objective and robust. Personally I'd prefer a Consumer magazine type analysis with products compared and rated

[mrsaneperson]

Can anyone really trust BRANZ appprovals after some of the scenarios read about in the media?

Aren't they just some monopolistic body, more or less churning in dollars for appraisals?