Protecting a house next to a stream from flooding?
June 18, 2022 3:19 PM Subscribe
I've been unsuccessfully trying to buy a house for quite a while, and there's one that I like now, but it's in a flood zone and I'm wondering if there's any way to protect it. It was built in 1930 directly next to a stream- most of the time, it's fine, but in a heavy rain I picture the water being sort of like a moat in front of the house. The front door actually has a bridge-like pathway over the stream to the street.
The basement level did flood once in the past, and the owners sealed off the doors on that level. Is there any way to truly protect it? How do mill houses survive next to water? Everything else about it is a good fit for me, and I could afford to invest a little in making it safer, if that is possible. Flood Factor rates it as a 10/10 flood risk, sigh.
The basement level did flood once in the past, and the owners sealed off the doors on that level. Is there any way to truly protect it? How do mill houses survive next to water? Everything else about it is a good fit for me, and I could afford to invest a little in making it safer, if that is possible. Flood Factor rates it as a 10/10 flood risk, sigh.
I understand your deep desire to own a home. But what Kangaroo writes above is similar to my experience. The flooding in my area is getting worse, not better. You can do everything in your power to protect a home, but what is uncontrollable is what somebody chooses to do (or not do) upstream.
posted by Juniper Toast at 4:58 PM on June 18, 2022 [8 favorites]
posted by Juniper Toast at 4:58 PM on June 18, 2022 [8 favorites]
So, first, I would speculate that buying this house, unless you have deep pockets, is a mistake. The previous owner walling off the basement is a red flag, plus all the other concerns you mention.
That said, there are a couple of ways to try and get an idea of how much risk you are taking on.
One is by digging into every oral, written, or other history available. What do the neighbors remember about floods? What is recorded in the newspaper archives, church records, or whatever else is available? This won't tell you exactly what it will look like under future conditions, but will give you a sense of what things looked like up to now.
The other would be quantitative: you would need to pay a qualified firm (in the US, that would include a professional engineer, hydrologist, and/or certified floodplain manager at a minimum) to do a hydrologic and hydraulic analysis of what the flood risk is looking like, both under current conditions and considering the effects of climate change. This will show you exactly where flood inundations are expected to reach at specific recurrence intervals (like, under the "100-year flood").
posted by Dip Flash at 5:13 PM on June 18, 2022 [1 favorite]
That said, there are a couple of ways to try and get an idea of how much risk you are taking on.
One is by digging into every oral, written, or other history available. What do the neighbors remember about floods? What is recorded in the newspaper archives, church records, or whatever else is available? This won't tell you exactly what it will look like under future conditions, but will give you a sense of what things looked like up to now.
The other would be quantitative: you would need to pay a qualified firm (in the US, that would include a professional engineer, hydrologist, and/or certified floodplain manager at a minimum) to do a hydrologic and hydraulic analysis of what the flood risk is looking like, both under current conditions and considering the effects of climate change. This will show you exactly where flood inundations are expected to reach at specific recurrence intervals (like, under the "100-year flood").
posted by Dip Flash at 5:13 PM on June 18, 2022 [1 favorite]
Bear in mind that in many places, flooding is becoming more frequent and more extreme due to climate change — and this is likely to continue for decades. If this applies to your area and the house has flooded in the past, it is likely to flood more frequently and worse in the future. Even if you are lucky personally and don't have a flood, this also means that flood insurance is likely to get even more expensive.
Mitigations are generally very difficult and expensive. In some cases, you can raise a house off the ground and eliminate the basement, but that is very expensive, if it is even possible.
posted by ssg at 5:21 PM on June 18, 2022 [6 favorites]
Mitigations are generally very difficult and expensive. In some cases, you can raise a house off the ground and eliminate the basement, but that is very expensive, if it is even possible.
posted by ssg at 5:21 PM on June 18, 2022 [6 favorites]
Response by poster: This house would not require flood insurance. I'm definitely well aware of the risks from climate change. Most interested in answers directly about potential solutions (e.g. whether inflatable plastic flood barriers help, etc). I would move everything out of the basement and not use it at all...
posted by pinochiette at 5:57 PM on June 18, 2022
posted by pinochiette at 5:57 PM on June 18, 2022
When it floods in your area how long does water stay high? I ask as some food barriers. e.g. soil/aggregate bunds will work for short duration events but then fail through leakage.
How resistant to upwelling are your soils? e.g. if this was Florida with a porous limestone base water comes up everywhere bund or no. But if your soils are silty/clayey you may have a barrier.
How much land do you have to work with? I know several houses that have a flood bund as little as a metre high and this protects them from all floods (as long as floods don't get worse).
Mill houses tend to 'work', as occupancy, if any, is on the second floor, also often situated where flood water can spread out on opposite bank.
As ssg says you could re-pile to a higher level - assuming house is timber; with current methods this is quick, plus service reconnections but still a lot of $$ - portable crane, lot of people and equipment
Is this site not controlled by local law? Like here in NZ earthquakes and sea level rise mean roading is being defunded where flooding is increasingly frequent, and all the houses effectively cut off.
posted by unearthed at 6:36 PM on June 18, 2022 [1 favorite]
How resistant to upwelling are your soils? e.g. if this was Florida with a porous limestone base water comes up everywhere bund or no. But if your soils are silty/clayey you may have a barrier.
How much land do you have to work with? I know several houses that have a flood bund as little as a metre high and this protects them from all floods (as long as floods don't get worse).
Mill houses tend to 'work', as occupancy, if any, is on the second floor, also often situated where flood water can spread out on opposite bank.
As ssg says you could re-pile to a higher level - assuming house is timber; with current methods this is quick, plus service reconnections but still a lot of $$ - portable crane, lot of people and equipment
Is this site not controlled by local law? Like here in NZ earthquakes and sea level rise mean roading is being defunded where flooding is increasingly frequent, and all the houses effectively cut off.
posted by unearthed at 6:36 PM on June 18, 2022 [1 favorite]
Best answer: I don't think anyone here can tell you how to protect this house without knowing the size and history of the creek, the type of foundation, the type of structure, the type of soil, the slope of the lot it sits on, the condition of the creek bed, proximity to groundwater infiltration from tidal bodies of water, and numerous other things. You need someone onsite, probably a structural engineer that you would pay for a consultation.
posted by oneirodynia at 7:12 PM on June 18, 2022 [7 favorites]
posted by oneirodynia at 7:12 PM on June 18, 2022 [7 favorites]
Mill houses are often damp and musty from frequent floods. I rented one and although it was beautiful, it had an unpleasant inner microclimate from the constant wetness.
posted by nouvelle-personne at 7:19 PM on June 18, 2022 [2 favorites]
posted by nouvelle-personne at 7:19 PM on June 18, 2022 [2 favorites]
This house is in Minnemopealot or surrounds, right? Oh, god... You know how the Midwest floods, right? O, pleasepleaseplease don't do it...
"I picture the water being sort of like a moat in front of the house." Oh, no. Not "in front of." In.
Your flood making a moat in front of the house picture is almost as cute as the picture I have in my head of this house with the little bridge over the little stream in the front yard. But these are not the right pictures. You don't need a cute picture when you're considering taking out enormous loans and spending ridonk money on property to which you'll be shackled for decades, you need a worst-case picture. Your picture should show the inside of the house and it should show raw sewage volcano-ing from all the toilets in the house and all of your furniture and your 'fridge floating on the newly formed tributary of the mighty Mississip' running through your front door.
So it's a two-step process. 1. Picture the flood in the house. 2. Decide not to get the house.
(At the very least, for the love of decency don't be thinking about what the city or whoever "requires." (?!) If it has flooded before, it will absolutely flood again, and it will absolutely flood worse. The house requires flood insurance, so resolve to get flood insurance.)
(How are you going to sell a house with a basement if the basement is a no-man's land? How are you going to live in a house, however picturesque, on top of a creepy empty (or... is it?) walled off basement?)
(Yes, listen to unearthed: even if the house doesn't flood, if access to the house becomes difficult and the city decides "...naaaw," you're SOL. There's a neighborhood in my tragic town whose bridge washed out and they can't get the city or the county to agree to build the bridge back so they have to park and walk with groceries and so on and emergency services can't get to them. Ex boyfriend, same town, moved his 1920s timber house out into the country and put it on pilings at enormous expense but the pilings weren't tall enough and twenty years later he was up to his hips in water in the kitchen--this just a few years after he spent ungodly money refinishing all the heart pine floors, too, sad trombone.)
(Yes, listen to oneirodynia. If you're seriously considering doing this, hire a structural engineer--chosen by you, not your realtor--to tell you whether it's a terrible idea or whether we're all overreacting.)
posted by Don Pepino at 7:26 PM on June 18, 2022 [11 favorites]
"I picture the water being sort of like a moat in front of the house." Oh, no. Not "in front of." In.
Your flood making a moat in front of the house picture is almost as cute as the picture I have in my head of this house with the little bridge over the little stream in the front yard. But these are not the right pictures. You don't need a cute picture when you're considering taking out enormous loans and spending ridonk money on property to which you'll be shackled for decades, you need a worst-case picture. Your picture should show the inside of the house and it should show raw sewage volcano-ing from all the toilets in the house and all of your furniture and your 'fridge floating on the newly formed tributary of the mighty Mississip' running through your front door.
So it's a two-step process. 1. Picture the flood in the house. 2. Decide not to get the house.
(At the very least, for the love of decency don't be thinking about what the city or whoever "requires." (?!) If it has flooded before, it will absolutely flood again, and it will absolutely flood worse. The house requires flood insurance, so resolve to get flood insurance.)
(How are you going to sell a house with a basement if the basement is a no-man's land? How are you going to live in a house, however picturesque, on top of a creepy empty (or... is it?) walled off basement?)
(Yes, listen to unearthed: even if the house doesn't flood, if access to the house becomes difficult and the city decides "...naaaw," you're SOL. There's a neighborhood in my tragic town whose bridge washed out and they can't get the city or the county to agree to build the bridge back so they have to park and walk with groceries and so on and emergency services can't get to them. Ex boyfriend, same town, moved his 1920s timber house out into the country and put it on pilings at enormous expense but the pilings weren't tall enough and twenty years later he was up to his hips in water in the kitchen--this just a few years after he spent ungodly money refinishing all the heart pine floors, too, sad trombone.)
(Yes, listen to oneirodynia. If you're seriously considering doing this, hire a structural engineer--chosen by you, not your realtor--to tell you whether it's a terrible idea or whether we're all overreacting.)
posted by Don Pepino at 7:26 PM on June 18, 2022 [11 favorites]
I might take this kind of risk, but it would be very situation dependent in a way that nobody can give you an answer for without seeing the specific property and assessing the surrounding area. And even then I'd want to know what kind of storm water regulations existed in the area. If there were none it would be a giant hell no regardless of other factors since construction upstream could seriously impact your flooding risk.
Things I'd consider are what kind of waterway, how big the overall flood plain of the stream actually is, how big the watershed feeding the stream is, whether the property is on a bend in the stream, whether it's on the inside or the outside of the bend, whether I was certain I'd have the resources to rebuild the access if necessary, etc.
posted by wierdo at 7:42 PM on June 18, 2022 [2 favorites]
Things I'd consider are what kind of waterway, how big the overall flood plain of the stream actually is, how big the watershed feeding the stream is, whether the property is on a bend in the stream, whether it's on the inside or the outside of the bend, whether I was certain I'd have the resources to rebuild the access if necessary, etc.
posted by wierdo at 7:42 PM on June 18, 2022 [2 favorites]
How do mill houses survive next to water?
I have some friends who converted and live in a house like this in France. The short answer is that the original builders arranged for the mill steam to have an overflow route upstream that would limit a floodwater rise. If you are looking for an actual mill house then that arrangement may be in place. Otherwise, if it isn’t- proceed with caution.
posted by rongorongo at 3:47 AM on June 19, 2022
I have some friends who converted and live in a house like this in France. The short answer is that the original builders arranged for the mill steam to have an overflow route upstream that would limit a floodwater rise. If you are looking for an actual mill house then that arrangement may be in place. Otherwise, if it isn’t- proceed with caution.
posted by rongorongo at 3:47 AM on June 19, 2022
I can tell you a bit about living in a house that had flooding. We bought a 100 yr old house (not picturesque) that had a double lot and a quirky little improperly capped well, with a basement apartment, freshly painted and carpeted, with a long term single tenant. She was lovely, paying below-market rent, and had a very tidy place. She had kids that would come over and she had super nicely put a plastic drop cloth under the dining table, which was in the carpeted area.
Our inspector did express concerns with the house, which was a weird disaster of a house, but we were in love with it plus it was the 3rd cheapest detached house in the whole of the east side of Toronto and the other two were visibly uninhabitable.
A few months after we moved in we went down to ask her about timing some renovations and I stepped on the plastic under the tablecloth and it…squished.
Long story short, we and our neighbours came to believe both our houses were built over an underground stream. We spent a lot of money and time on basement waterproofing and foundation work, weeping tile, French drains, and gutters. We did manage to keep the water at bay some years (stopped renting the basement for other reasons.) Each time it flooded, mind you there were cupboards and baseboards and drywall and all, we had to rip things apart. Once we weren’t renting we took the carpet up permanently.
The March my daughter died we came home after 5 days at the hospital/NICU, baby less. Opened the door to…the now-familiar scent of wet basement, musty. We couldn’t handle it right then, were funeral planning, I was physically wrecked etc. We ignored it and cracked the windows despite the cold. A few weeks later we went downstairs and…there was mould up all the walls.
(We eventually sold to a developer. When he dug down for the two houses there was 4 ft of water. Dunno how he fixed it.)
So my story is here to tell you please don’t just plan for what you can do. Plan for the times in your life you need your house to be solid because you can’t get out to sandbag it or whatever.
posted by warriorqueen at 4:37 AM on June 19, 2022 [6 favorites]
Our inspector did express concerns with the house, which was a weird disaster of a house, but we were in love with it plus it was the 3rd cheapest detached house in the whole of the east side of Toronto and the other two were visibly uninhabitable.
A few months after we moved in we went down to ask her about timing some renovations and I stepped on the plastic under the tablecloth and it…squished.
Long story short, we and our neighbours came to believe both our houses were built over an underground stream. We spent a lot of money and time on basement waterproofing and foundation work, weeping tile, French drains, and gutters. We did manage to keep the water at bay some years (stopped renting the basement for other reasons.) Each time it flooded, mind you there were cupboards and baseboards and drywall and all, we had to rip things apart. Once we weren’t renting we took the carpet up permanently.
The March my daughter died we came home after 5 days at the hospital/NICU, baby less. Opened the door to…the now-familiar scent of wet basement, musty. We couldn’t handle it right then, were funeral planning, I was physically wrecked etc. We ignored it and cracked the windows despite the cold. A few weeks later we went downstairs and…there was mould up all the walls.
(We eventually sold to a developer. When he dug down for the two houses there was 4 ft of water. Dunno how he fixed it.)
So my story is here to tell you please don’t just plan for what you can do. Plan for the times in your life you need your house to be solid because you can’t get out to sandbag it or whatever.
posted by warriorqueen at 4:37 AM on June 19, 2022 [6 favorites]
When we bought our first house there weren't water issues. But over the years we lived there the water table came up and SE Michigan now has 44% more rainfall than 30-40 years ago. Over the years we had that house we ended up rebuilding the foundation and putting in a tile field and regrading the yard. I don't own that house any more and I sincerely hope those fixes solved it but it was a LOT of money and stress to address and that was a house that we didn't move into knowing there were flooding issues.
Find a different house. I always tell people look at the basement before you look at anything else - if it's problematic walk away before you fall in love with all the nice stuff upstairs. It's not worth it.
posted by leslies at 5:43 AM on June 19, 2022 [4 favorites]
Find a different house. I always tell people look at the basement before you look at anything else - if it's problematic walk away before you fall in love with all the nice stuff upstairs. It's not worth it.
posted by leslies at 5:43 AM on June 19, 2022 [4 favorites]
Best answer: Mill houses are often damp and musty from frequent floods. I rented one and although it was beautiful, it had an unpleasant inner microclimate from the constant wetness.
If you have not had an inspection done, I would get someone licensed to take a careful look at the foundation + basement - I have friends that own a house that's ~1/2 a block from a buried/channelized stream under a road, and they have had ongoing issues w/subsurface water saturating the soil in their yard and degrading the 100+ year old foundation wall. As unearthed points out, the water you can see on the surface is often only part of the equation.
posted by ryanshepard at 6:29 AM on June 19, 2022 [2 favorites]
If you have not had an inspection done, I would get someone licensed to take a careful look at the foundation + basement - I have friends that own a house that's ~1/2 a block from a buried/channelized stream under a road, and they have had ongoing issues w/subsurface water saturating the soil in their yard and degrading the 100+ year old foundation wall. As unearthed points out, the water you can see on the surface is often only part of the equation.
posted by ryanshepard at 6:29 AM on June 19, 2022 [2 favorites]
This question reminds me of some friends who had significant water in their basement that was not covered by flood insurance because the water came UP from the ground instead of DOWN from the rain.
Also I've seen houses moved into the air, but you forego the basement entirely.
posted by aetg at 6:47 AM on June 19, 2022 [2 favorites]
Also I've seen houses moved into the air, but you forego the basement entirely.
posted by aetg at 6:47 AM on June 19, 2022 [2 favorites]
Flooding is a thing in lots of areas of the UK. Climate change means that flooding here is increasing in frequency. Here's information about how homeowners in flood-prone areas are encouraged to make their homes resistant and resilient to flooding. Reputedly, it takes most people more than a year to recover from their first home flooding, even with insurance covering much of the cost.
posted by plonkee at 7:18 AM on June 19, 2022
posted by plonkee at 7:18 AM on June 19, 2022
I owned a house that had a basement that flooded every spring. It was over 100 years old and that's just what it did. We just kept things off the basement floor and had a sub-pump and dehumidifier running all the time. We could also easily see how high the water got as it left a line on the wall of the basement (from minerals being deposited). People in my neighborhood finished their basement which must have been a nightmare for them - don't do this! Go back and look at the basement to see if there is a mineral line as to where the water has reached. If there is no line, and you know there has been flooding - I would worry that you are not being given accurate information about the house and that something is being covered up. If there is a line, then make an assessment as to what would be required to resolve it (could a sub-pump take care of it? or is it several feet and you have a real issue).
This was an area where the water table was coming up from underneath the house. Where I am living now (also with 100 year old houses) the water table is not the issue, but rather water from the street pouring down driveways into basements is an issue. For that people use sandbags and rent large fans and dehydrators. Periodically the mold-man comes to help out. This strikes me as more of a problem, but people seem to keep buying these houses and just dealing with it.
People also spend some cash to have their houses raised a few feet off the ground if they don't have a basement). Not sure what the cost is, but again folks seem to think that this is worth it and it appears to help protect the house.
posted by Toddles at 12:04 PM on June 19, 2022
This was an area where the water table was coming up from underneath the house. Where I am living now (also with 100 year old houses) the water table is not the issue, but rather water from the street pouring down driveways into basements is an issue. For that people use sandbags and rent large fans and dehydrators. Periodically the mold-man comes to help out. This strikes me as more of a problem, but people seem to keep buying these houses and just dealing with it.
People also spend some cash to have their houses raised a few feet off the ground if they don't have a basement). Not sure what the cost is, but again folks seem to think that this is worth it and it appears to help protect the house.
posted by Toddles at 12:04 PM on June 19, 2022
I think it depends on your risk tolerance,your access to cash, and your city's pro activeness to flooding. My in-laws house has flooded 3 times since 1952. Since then the city has spent a boat-load on a hideous flood control channel just beyond their backyard. Houston Texas? Nobody really cares. Houses flood, they don't have basements. They tear out 2 feet of drywall at someone's expense and move on.
I think Americans and Europeans (or older cultures) treat floods very differently. My relatives old ranch house was just a few feet higher than the river - if it floods, it floods. They weren't built nearly at tightly, they didn't care about mold as much, and they didn't have lots of expensive systems (electrical, plumbing), and they had to carry water, so a flood or two was worth the risk. So many buildings in Europe are built to the edges of rivers where as that's almost unheard of in the US, in modern buildings.
posted by The_Vegetables at 9:41 PM on June 19, 2022
I think Americans and Europeans (or older cultures) treat floods very differently. My relatives old ranch house was just a few feet higher than the river - if it floods, it floods. They weren't built nearly at tightly, they didn't care about mold as much, and they didn't have lots of expensive systems (electrical, plumbing), and they had to carry water, so a flood or two was worth the risk. So many buildings in Europe are built to the edges of rivers where as that's almost unheard of in the US, in modern buildings.
posted by The_Vegetables at 9:41 PM on June 19, 2022
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posted by Kangaroo at 3:46 PM on June 18, 2022 [19 favorites]