Flood-proof Tiny House: Planning the Location
Whether you are building a tiny house, play house, workshop or shed on your land, you need to prepare the spot.
The first, VERY first step is to make sure your building is not going to flood. Even before you plan the foundation, you need to plan the location.
Is the location for your tiny house above flood plain? How much above flood plain? Even if the land is above flood level, does that particular area flood anyway?
If you have no other choice, even if the area floods, you might be able redirect the water flow.
Ways to Redirect Water
A berm acts as a wall or dam to divert water. It doesn’t have to be very high and it doesn’t have to be steep. As long as it is high enough and in the right place, it will redirect the water so that it won’t wash into your little house.
The photo above shows a campground with some serious flood remediation by NRCS Montana. These berms are really high. Ours are much lower. We don’t get serious flooding, we just want to redirect the water. I’m sure these berms will look much better after they get some grass on them.
The more gradual the slope, the easier it will be to mow. Some people add ornamental plants, but keep in mind that this area gets less water.
Our berms don’t show at all. They are much lower than the ones in the photo above.
A swale is a lowered place in the yard to direct water. If it is wide and shallow, you can barely tell it is there and it is easy to mow. But, when it rains, the rain is directed away from your little house.
I tried to take a photo of our swale, but it just looks like grass.
You can dig an area low enough to divert a lot of water, and then fill it with river rock. When it rains, it fills with water, instead of flooding the whole area. Make sure it runs somewhat downhill and away from anything you don’t want to flood.
You can find a lot of Dry Stream Bed Pins on Pinterest.
You can dig a ditch or trench if you need to divert a lot of water. The more water, the deeper and wider the ditch. Put a culvert in wherever you need to cross. Or lay two smaller culverts side-by-side if the ditch is wider.
Use just one of these methods or a combination.
Make these changes before you start on your foundation and keep an eye on the area during the highest rains. Then you can tell if it’s not working before it damages your new little house. You can add another method or adjust the one you’ve used. You will see if you need to make your berm higher or change the location. You might have to make your ditch or swale deeper or wider. You may find that you need to redirect the water better.
The photo above is the ditch when we first bought our land. It filled up when there was a lot of rain, then overflowed flooding the field. We had to make the ditch wider and deeper.
What if it still floods?
If it still floods, even a little bit, don’t ignore it.
If you can’t prevent flooding in the area you want to put your little house, shed, or other building it is going to cost more and take more time. Consider choosing another location.
If this spot is your only choice. Measure how deep it floods. If you are actually below flood plain, how far below?
Being below flood plain or in an area otherwise prone to flooding doesn’t make it impossible to build, but you will have to raise your building high enough to protect it.
How to Raise Your Tiny House So It Won’t Flood
You will need to raise your tiny house or other building so that it won’t be flooded. There are quite a few ways to do this.
You can build the level of the ground higher by grading, moving dirt from other areas of your land or bringing in fill dirt.
Foundation and Backfill
You can put in footers and a block foundation to get high enough. You will probably want to backfill so that the area under the house doesn’t fill with water. You don’t want your house sitting on a pond or swamp.
You can put your tiny house or other building on piers. Piers can be built out of concrete block on a cement footing or use a concrete tube form like Sonotube. This way even if water flows under and around your building, it won’t get into it or wash it away.
Sonotube concrete tube forms can be used to raise your building above flood level.
Depending on what you are building, perhaps you can use 4 x 4 posts, as if you are supporting a deck or porch. A Sonotube concrete tube form can be used make the cement footing for 4 x 4s.
Don’t skip or rush planning and preparing the location of your building.
Preparation now will save you later.
Now you can Plan the Foundation >