Long story short, we ended up installing a french drain on two sides of our house, putting a drain at the end of our driveway to redirect water [from just running down our driveway to our house], having the front wall foundation rebuilt and jacked up because the footer had nearly completely eroded (1970s house), and still needed to add two 24" square drain boxes in the back yard (with buried 4" PVC draining into the creek at the back of the property) to remediate all this. It was also a tree-filled lot and the drain boxes would almost immediately clog with leaves during heavy rains, so I spent a lot of time out there in ankle to knee deep water with a rake to keep the drains clear.
This still wasn't enough! We got a so much surface run-off from our uphill neighbors that it looked like a sheet of rushing water across our backyard during heavy storms. We had a creek at the back of the property but were not allowed to mess with it because of Corps of Engineers easement regulations. At the end of the day, we finally solved our problems by getting an agreement from our neighbor to let us dig a surface water drain from the low point in their yard into the creek, and then we'd build a "temporary" (cf prior easement rules against permanent walls) berm along the property line to prevent surface water from coming into our yard at all. That "berm" was 76 bags of Qwikrete stacked three high and covered with grass clippings, yard waste & mulch. Technically we could have removed it if the city had inspected, but it was very much a cement wall.
We have never since, and never will, build or purchase a house at the bottom of a hill.
It's particularly demoralizing to see the scope of the problem when it's all that water flooding your property and know there's nothing you can do in the short term, and even the long term is just trying different things and hoping they work, knowing that it will probably take a few tries.
Perhaps the balcony over your front door is not properly constructed and is not properly shedding rain, so one day during a torrential thunderstorm you suddenly have a flood coming in OVER your front door.
Perhaps your water heater pan is not draining correctly, and one day you have a catastrophic containment failure in your water heater, causing an interior flood.
Perhaps you change the toilet in an upstairs bathroom, and the new modern toilet is not providing enough water per flush to make the long run of the upstairs plumbing. So, it clogs up over time, then one day it backs up while you’re taking a shower, and you’re standing in multiple inches of grey water. Then the water does slowly drain, but you don’t notice that the pipe has cracked above the clog and it’s actually flooding into the room below, through the light fixture.
Perhaps the main schedule 40 PVC pipe from the water main at the street slowly develops a crack, due to the roots of a tree nearby, and one day you discover that the water pressure in your house is really low and that you have flooded the whole street.
Guess which of these have happened to us?
Building codes exist for reasons. Sometimes they seem frivolous, but often they're there for a damn good reason.
I've seen a number of homes in my area where the builder received special permission to build right where the drainage needs to go. Some were beautiful and I was tempted to give it a shot, but your story reminds me that I need to trust my gut on this issue and head for high ground.
Beat it with 2 ditches, a drain, a berm and 2 pumps.
Further - if you never have a problem the value of the inspection is zero. If you do have a problem the value of an inspection after the problem has occurred is minimal. The value of an inspection that prevents a problem is something - but how to quantify that is difficult.
Topographic maps, flood risk maps, wildfire risk maps, maps of services nearby (substations, transformer locations, storm drains etc), easements, special planning/protection zones, surrounding area zoning etc.
These should all inform your decision. I've vetoed houses because they back onto nature/wildlife reserves, are too near substations, are in flood risk areas etc
Why is this a bad thing? To a naive person, it might seem like a good thing, because you get to look out into a forest rather than someone else's yard.
Essentially because nobody was allowed to trim/maintain the trees due to it being a natural habitat. It's nice to look at but when a 60m tree falls in a storm and wipes out your house it's not great. The reserve was also on the north side of the property and down here in the southern hemisphere that means that every year as the trees grow your house gets more and more shade with accompanying maintenance issues.
I should add that people may weigh that up and be happy to live there, but people should be aware of the risk/benefits before they buy. Natural light/property orientation and shading is a major issue that most people forget about.
If you personally know any architects or general contractors in the residential market, they should be able to recommend someone.
It's all pretty silly, really, especially considering the hottest markets, where you either want a house or you don't, and if you you'll probably pay top dollar with no contingencies and possibly not even your own inspection... since the seller knows if you don't buy it someone else is in line right behind you. Most of the time, houses sold this way aren't in significantly worse shape than those that are fully inspected and repairs made before the transaction.
Overall, this has led me to believe that, in most cases, pre-sale inspections don't really benefit anyone, especially since it's so difficult for buyers to seek E&O recourse/damages against either an inspector or seller after the sale closes.
We took that list back to the sellers (who were then legally required to provide a copy of that report to other future buyers), and we simply waived the little stuff. We wanted them to fix the big stuff. They didn’t want to do that, so they came down on the price by a considerable amount. He saved us tens of thousands of dollars.
Now, given the problems we’ve had since then which the inspector didn’t identify, we would have paid back more than what he saved us — Except for insurance coverage. USAA is really good about paying out on claims, when many other insurance companies would weasel out.
We love this house, we love this neighborhood. If we had to do it over again, I think we would have pressed harder to get even the minor problems fixed or to get the seller to come down even further on price. But I think we probably would have still bought this house.
I don’t blame the inspector for anything he missed. Most of those problems were well disguised, until such time as there was an actual catastrophic failure. He couldn’t have known. If I knew his name and contact details, I would recommend him to future buyers in the Austin area.
And we’re definitely sticking with USAA.
There was a ditch out back but it obviously wasn't deep enough. I did the math and ended up with an astounding amount of water flowing by (something like 20,000 gallons per minute[0]) and complained to the builder about it. They sent a couple of guys out there who installed two 4" corrugated drainage pipes and said it was good enough.
When the next big rain happened, where those pipes emptied out there was a 3 foot tall fountain of water from the pressure. It was an amateur Bellagio, lol. The yard still flooded but luckily didn't come into the house again.
Since then, the landscaping came in throughout the neighborhood which controlled the runoff. But it taught me a lot of respect for getting slopes & drains right - Always use a larger pipe than you think you'll need.
[0] The formula seems to be: V = 0.408 × Q/(D^2) where V is velocity in feet-per-second, Q is the flow rate in gallons-per-minute, and D is the diameter of the pipe in inches. I estimated the diameter based on the land profile that was underwater, and timed the velocity by following twigs/leaves floating by.
One of my friend works in reinsurance and his favourite joke is that every time the insurance company pays a claim, someone is getting fired. Obviously a joke but it seems to paint a fairly accurate picture of how the business is run.
Vanguard(the brokerage) is structured the same way pretty much, except it's the various mutual funds(like VTSAX/VTI) that own the larger corporation. So far the infection of c-suite salaries continually growing larger and larger hasn't gotten to Vanguard yet, but they are now a few CEO's removed from the original founder(Jack Bogle), so it's probably about time that shift starts to happen.
> The people in charge(C-Suite) have zero incentive to ever refund any annual profit.
For example, in 2020:
> USAA, the country’s fifth largest property-casualty insurer, will be returning $520 million to its members.
If what you say is true, why did they return any money at all? They could easily pay that to C-suite and senior execs in huge bonuses.
Also, to clarify, the correct term is "mutual insurance", which Wiki describes as:
> A mutual insurance company is an insurance company owned entirely by its policyholders. It is a form of consumers' co-operative. Any profits earned by a mutual insurance company are either retained within the company or rebated to policyholders in the form of dividend distributions or reduced future premiums.
Certainly, they're in business to make money, and helping customers is just part of the process, not their goal.
But --- it's in the customers' interest for the company to be accurate about accepting and denying claims. If the company accepts claims that should be denied, that means higher premiums. If the company denies claims that should have been paid, that may result in the company having to pay those claims after appeal/lawsuit and possibly with penalties; penalties get paid by the pooled insureds one way or another.
Insurance fills a need and is not just an evil company doing evil. Most insurance covers risks of loss that the insured would be unable or unwilling or at least unhappy to cover themselves. For most homeowners, if their house burns down, they would be unable to rebuild without insurance, unless there was clear liability from a person or company with big pockets.
> I honestly don't think consumer insurance is worthwhile
This is consumer insurance, so your typical auto, home, renter's, etc. policies. If you need commercial or E&O coverage, ask your broker to check them against the AM Best rating list.
To get a flood policy you would have to speak to a broker about whether you qualify for the National Flood Insurance Program. They won't issue a policy to you directly.
The previous homeowner put in a DIY french drain, but either he didn't do it right, or it's too flat, or it's too small, or it is clogged. We instead get surface water flow and erosion along the same path where the french drain runs.
(It doesn't help that when our neighbors got sand delivered for an above ground pool bed, the delivery truck dumped the entire pile of sand ON TOP OF the river rock exit basin for our french drain. The sand was later removed/used but I was still upset; unfortunately it was my brother in law who ordered the sand. Since the drain is above it I don't think it went in the drain, but maybe this rock basin was supposed to be a dry well.)
I am thinking of building something like your concrete berm along my back fence line, possibly modifying the french drain to just transfer the water from the far side of the berm to the exit over the cul de sac rather than trying to absorb it from the ground.
Yes he does name soil migration as the biggest problem with subsurface drains, but to be fair the video is contextualized around dams.
The spirit of my comment was intended to be helpful for folks attempting this stuff at home, not to suggest a lack of good info in the video.
I wonder, does climate change also affect those calculations, with the need to adjust those bounds upwards? I remember the (technical) term "100 year flood" getting lots of ridicule in the last years because we already got multiple "100 year floods" in the range of a decade.
Development happens faster than the flood maps get redrawn.
But that got me thinking, how often do they adjust these estimates? Was a "100 year flood" in 1950 less than in 2000, say?
Obviously it'll be different for different areas, especially between countries, but still.
The 1:100 year safety level should thus be considered a bare minimum for high impact events. In the Netherlands water infrastructure is designed to withstand the 1:10.000 year storm for catastrophic events, and e.g. 1:1.000 year storm for high impact events.
But even with higher safety standards, it is key to design not only for the current climate, but for the future climate over the design life of whatever you are building. Extrapolating 1:10.000 year events from 30 years of observations might seem sketchy already, but with all the uncertainties in climate change predictions is a bit of a stretch.
Long term observed water levels are fed into a model with normal distribution, and a 100-year flood is then defined as 99-th percentile of the model. This means that there's a 1% chance of a 100-year flooding each year.
Global warming and climate change have an effect that there's a lot more water vapour in air. Same air mass can deliver more rainfall on a given territory, pushing observed water levels into higher extremes, meaning what used to be 100-year flood is now 25 (4% yearly chance), 10 (10% yearly chance) or even 5-year (20% yearly chance) flood.
https://www.usgs.gov/special-topics/water-science-school/sci...
I wonder what building codes require, ie from engineering and inspection POV, like can the things you mention even be built today? If so isn't this a failure of the planning departments?
Yes definitely, just depends on area and your local geology / codes.
How do you incorporate this into a drain design?
A proper drain requires extensive soil testing for particle size. Video goes over this along with the issues of geotextiles.
No one is doing soil tests for these unless they are installing huge critical commercial infrastructure.
Incidentally, our roof had gutters/drainage originally. We put in our own french drain after about 8000 hours of research, and decided to re-route the roof drainage to right above the new french drain (separate pipes) because the roof drainage broke at some unknown point and was dumping water around our foundation piers (yay...). Well, our roofers came and installed gutter guards after all this, which caused the gutters to shed 60% of the water into the drainage area because of the way they're angled. If we hadn't put in a french drain, it'd be a real problem, but as it is now, it's a mild annoyance that I keep telling myself I'll fix.
The article seems to be quite clear that, for critical applications, one should not use geotextile fabric at all — instead one should use (appropriately selected!) sand.
We were a bit naive buying our new construction home. It's the only home on the street with a basement due to the high water table. One year after purchasing, Hurricane Ida hit and we had water up to the door handles in our basement. Our primary sump pump runs constantly for 18 minutes then off for 18 minutes 24/7. We have a backup pump on the other side of the basement connected via the perimeter drain, and a liberty water backup pump. The only addition since Ida is a whole house generator and superior window wells.
During Ida, the street was flooded, the drainage systems were backed up, and there was no where to pump the water to.
I'm assuming it's a fully-enclosed basement? I.e. no walk-out side?
The best you can likely do is waterproofing the basement walls + pumping out from inside or an inside-perimeter drain. But that's only racing pump_out_flow > seep_in_flow.
And that's a bad game to be in, because water under pressure (which it will be a story below ground) finds a way.
I'd make the basement flood tolerant (limit mold-hosting materials and places water can be trapped) + pump it out quickly after it floods + buy a dehumidifier, and accept it's going to happen.
French drains around the perimeter help, but you're literally fighting water from all directions... including directly underneath.
Have a perimeter French drain but a crack in the slab? Enjoy watching water bubble up from that crack once things get saturated.
There isn't a "perimeter" per se, because water is literally coming from depth (in most locals / soil types).
So drain/pump just creates drier 3d soil areas. Whether that's enough to attract all the surrounding water (at a high enough rate) that would otherwise be infiltrating depends on soil permeability (e.g. sandy or clay?).
A lot of the "handyman"-type "dry basement" shops have no idea about any of this, toss a generic solution in there, and then blame the gods if it doesn't work (and they've billed for time-consuming and expensive excavation).
It gets dicey applying internal barriers, because one needs to be thoughtful about making sure there's a place for water to go when it's actually too much (you don't want an internal barrier to be a dam holding back all the pressure), but it can be an option.
They sell them in membrane form or paint-type form.
Soil migration is the number one failure mode. This is mentioned but perhaps a bit understated in the video.
To prevent soil migration you absolutely need commercial grade geotextile fabric wrapping the gravel and pipe.
You can buy pipe with much bigger and more numerous holes than the tiny slits depicted in the video. That also obviates the need to decide what orientation the holes should be.
Void space is the most critical factor when choosing gravel. You need a lot of space between the rocks to support fast drainage. Do not use playground pebbles or anything similar. Pay close attention to the type of aggregate you’re buying.
Calculate how much water you actually need to drain. You can use the “100 year flood” values for your locale to get an upper bound on rainfall, then multiple by drainage area. This is especially important if your roof is part of the watershed.
https://www.usgs.gov/special-topics/water-science-school/sci...
Sometimes there is insufficient gradient to move the water anywhere, ie the land is too flat. In this case you may be better off building a drywell, which is constructed very similarly.
https://en.m.wikipedia.org/wiki/Dry_well