New Construction Basement Waterproofing (foundation, laminate, drains, painting)

[PS90]

We are building a new house with a daylight basement. One of the concessions that we made with the contractor to save money is that I will be doing the basement waterproofing myself.

This is going to be fairly important as our land has a very high water table, especially in the spring, and I expect the below-grade side of the daylight basement will be subjected to a fair amount of pressure from water.

We have decided on a fairly simple French drain using perforated flexible pipe in washed rock at the footings, but I have basically no clue what's best to waterproof the concrete walls.

It seems that options include:

1) An elastomeric coating - basically a rubbery coating that is very waterproof, but apparently these tend to de-laminate and/or wear-out within 8-10 years.

2) A dimpled membrane - these provide a gap between the membrane and concrete so water can easily drain to the French drain. Seems like a good idea, but I've heard that they tear easily during installation and/or backfilling.

3) A crystalline coating - basically a paint-like coating on the outside that is made up of cement and little crystals that fill-in the pores of the concrete and make it totally waterproof. The downside appears that - if the concrete cracks at some point - then the crystals can't bridge the crack if it's bigger than 0.4mm (that's pretty small).

At this point I am planning on using the crystalline coating, but I am open to others' opinions on what is best for making sure that our basement stays dry.

Thanks!

[MrRational]

Originally Posted by PS90

We are building a new house with a daylight basement.
...our land has a very high water table, especially in the spring,

One of the concessions that we made with the contractor to save money
is that I will be doing the basement waterproofing myself.

Stop right there. You've been snookered.

[PS90]

Originally Posted by MrRational

Stop right there. You've been snookered.

Why? It was my idea to do this ourselves to save money. I admit that I've never done anything like this before, but I've certainly done excavation work and painting, and the techniques themselves don't look overly difficult - I'm just not sure which technique/approach is best.

Or are you saying that there are some Super-Secret-Contractor techniques that random idiots like me will never know?

[villageidiot1]

Originally Posted by PS90

Why? It was my idea to do this ourselves to save money. I admit that I've never done anything like this before, but I've certainly done excavation work and painting, and the techniques themselves don't look overly difficult - I'm just not sure which technique/approach is best.

Or are you saying that there are some Super-Secret-Contractor techniques that random idiots like me will never know?

At least you will know that it is done right. I bought a newly constructed house and a few months later, we started getting water in the basement. Spent a couple years arguing with the builder over whether the French drains were installed correctly. I inspected a few other houses he built in the neighborhood and it appeared he just push dirt in over the perforated pipe. The bigger issue is where the French drain and your downspouts drain to.

[MrRational]

Originally Posted by PS90

Why?

Warranty is the main reason.
You've allowed the builder to shift that entire range of responsibilities onto YOUR shoulders.

If you can't afford to HIRE the contractor-builder to do a job that can be guaranteed...
then either pick a different site or a different foundation type; like a raised crawl.

[Ted Bear]

Membrane leeching into French Drain is the way to go. Probably want to seal the external walls with a waterproof coating first. Run gutters and down spouts to daylight well away from the foundation given the already existing high water table .


If it is really serious, place a collar drain around an internal floating slab and have it empty in a sump pump basin. Again, run the effluent from the sump pump well away from the foundation.


You can't afford to mess around with this area of your project. Consider it part of the 10% reserve you put aside for "changes".

[JonahWicky]

I think you're making a huge mistake. This is a critical part of the building envelope. It's not the right place to learn a specialized skill, and definitely not wise to absolve the builder of responsibility for a dry basement. He's going to point the finger directly at you if there is ever any type of foundation problem.

If you have experience with excavating and painting, why not do the underground utility trenching or the interior painting instead? Leave the important stuff to the pros with big insurance policies and lots of resources.

[PS90]

Originally Posted by Ted Bear

Membrane leeching into French Drain is the way to go. Probably want to seal the external walls with a waterproof coating first. Run gutters and down spouts to daylight well away from the foundation given the already existing high water table .


If it is really serious, place a collar drain around an internal floating slab and have it empty in a sump pump basin. Again, run the effluent from the sump pump well away from the foundation.


You can't afford to mess around with this area of your project. Consider it part of the 10% reserve you put aside for "changes".

Thanks very much for the advice.

I have actually been thinking about doing either the rubber waterproofing coating or the crystalline waterproof coating and then cover that with the membrane. But then I was thinking that was overkill - but maybe not?

[K'ledgeBldr]

I won't continue the lambaste- if you haven't "heard" it by now, you won't ever.

So, on to the question- an elastromeric coating with either a wicking protection layer, or a channeled protection layer. Concrete can do weird S#!T- Be Prepared!

The perimeter drain you have selected is/will be a very weak point of the entire drainage system due to the ever present high water table. In this case I'd probably use 6" PVC drain tile (perf'ed pvc), sleeved or wrapped; not perf'd corrugated. Perf'd corrugated can become clogged very easily when constantly subjected to water and fine sediment.

It may even be worthwhile to add one or two standpipes to finished grade for cleanout.

Grade is very critical- I'd probably err on the side of caution and increase it abit- and pipe downspouts to the street if possible.

[chet everett]

Originally Posted by K'ledgeBldr

I won't continue the lambaste- if you haven't "heard" it by now, you won't ever.

So, on to the question- an elastromeric coating with either a wicking protection layer, or a channeled protection layer. Concrete can do weird S#!T- Be Prepared!

The perimeter drain you have selected is/will be a very weak point of the entire drainage system due to the ever present high water table. In this case I'd probably use 6" PVC drain tile (perf'ed pvc), sleeved or wrapped; not perf'd corrugated. Perf'd corrugated can become clogged very easily when constantly subjected to water and fine sediment.

It may even be worthwhile to add one or two standpipes to finished grade for cleanout.

Grade is very critical- I'd probably err on the side of caution and increase it abit- and pipe downspouts to the street if possible.

Originally Posted by PS90

Why? It was my idea to do this ourselves to save money. I admit that I've never done anything like this before, but I've certainly done excavation work and painting, and the techniques themselves don't look overly difficult - I'm just not sure which technique/approach is best.

Or are you saying that there are some Super-Secret-Contractor techniques that random idiots like me will never know?

Originally Posted by PS90

We are building a new house with a daylight basement. One of the concessions that we made with the contractor to save money is that I will be doing the basement waterproofing myself.

This is going to be fairly important as our land has a very high water table, especially in the spring, and I expect the below-grade side of the daylight basement will be subjected to a fair amount of pressure from water.

We have decided on a fairly simple French drain using perforated flexible pipe in washed rock at the footings, but I have basically no clue what's best to waterproof the concrete walls.

It seems that options include:

1) An elastomeric coating - basically a rubbery coating that is very waterproof, but apparently these tend to de-laminate and/or wear-out within 8-10 years.

2) A dimpled membrane - these provide a gap between the membrane and concrete so water can easily drain to the French drain. Seems like a good idea, but I've heard that they tear easily during installation and/or backfilling.

3) A crystalline coating - basically a paint-like coating on the outside that is made up of cement and little crystals that fill-in the pores of the concrete and make it totally waterproof. The downside appears that - if the concrete cracks at some point - then the crystals can't bridge the crack if it's bigger than 0.4mm (that's pretty small).

At this point I am planning on using the crystalline coating, but I am open to others' opinions on what is best for making sure that our basement stays dry.

Thanks!

The issue is NOT that there is some "super secret" way to waterproof the foundation of a newly built home BUT that any builder who is trying to foist this CRITICAL ELEMENT of the construction onto the owner IS NOT BEHAVING IN AN ETHICAL OR TRUSTWORTHY MANNER! Especially given that the area has "a high water table" the builder is basically saying they are not optimistic that this won't be a potential area of grief.



If the OP is foolish enough to relieve the builder of the responsibility of ensuring this home has a dry basement if the OP also willing to take on the HUGE potential cost of unearthing the perimeter drains and waterproofing AFTER the home is complete and paying a real professional to do things properly?



While it may seem like this "down in the mud" type work is all about careful labor and proper material selection the fact is LOCAL CONDITIONS are a big factor -- that includes soil composition, site topography, climate, and even local custom / expertise. The evolution of techniques and materials means that you might end up spending a whole lot more than is necessary and /or putting forth much more work to get inferior results. Cost is ultimately not as important as effectiveness and in areas where the specific situation is challenging the experience is really the key to effective waterproofing!



It would be one thing if the OP has experience with this sort of thing, or maybe has family / friends who do this sort of work for a living. I also would have no problem if the OP was just doing a bit of generic research so they'd have a context to understand the recommendation of their contracted builder. Instead my fear is that these vital steps in ensuring a well built home are not something for a generally competent but not specifically knowledgeable homeowner to DIY...