Crawl Space Sump Pump Install
Sump Pump Install
Like many cabins and homes built in the 1950s, our cabin has a dirt crawl space. And, like many dirt crawl spaces, ours is a damp, musty, fairly disgusting place.
The first time I ventured into our crawl space, there was standing water in the space. Not good. Knowing that the ideal crawlspace mimics that of the conditioned living space of your home, I knew we had a lot of work to do. And I knew a sump pump install was just the beginning.
The perfect crawl space is clean, dry and sealed. Ours was not. To remedy our sick crawl space, I planned to first address the standing water and excess moisture in the space. Later I plan to install a vapor barrier over the crawl space to further reduce moisture and soil gas transmission into our living space.
Crawl spaces often have several reasons for excess moisture. Our crawl space was no exception. The floor of the space was very close to the existing water level, we have no rain gutters on the cabin, and much of the yard slopes improperly toward the home. All of these issues need attention, but as a start I plan to add a sump pump to get the current water out of the space.
Common Causes of a Wet Crawl Space or Basement:
- Floor of space lower than ground water level
- Roof run-off and rain entering space (no gutters, blocked or leaking gutters, slope issues)
- Condensation of moisture from humid air in space (ventilated crawl spaces, condensation on cool surfaces or ducts)
- Lack of moisture barrier between soil and space
- Leaking plumbing
The above illustrates many of the issues contributing to our damp crawl space. Installation of a sump pump is a fairly straight forward project. Read on to see how I did it in our cabin crawl space.
How to install a sump pump
Preparation and Materials
- Level: Intermediate
- Time: 1 – 2 Days
- Cost: $300 – $500
Project Big Picture
- Plan placement.
- Dig sump pit.
- Dig / Place drain tile (optional)
- Place sump basin.
- Place sump pump in basin.
- Install sump pump plumbing.
Materials – Sump Basin, Pump and Drain Tile
Sump Pump Install – Tools / Supplies
- Shovels, hoe, rake and similar tools to dig sump pit, trenching for drain tile and aggrigate application and leveling
- Hand tools to pipe discharge, mount hangers, install basin
- Hole saw or similar to cut drain pipe access holes in sump basin
- Tools for PVC discharge pipe circuit install
- Drill, hammer for installing foundation pin fasteners
- Tools, supplies for PVC circuit install
- Bucket(s) or similar for dirt removal
How to install a sump pump – Step by Step
- Organize tools and supplies.
Gather sump basin, sump pump, sump check valve, drain tile, aggregate, tools, plumbing materials, and light source.
- Prepare crawl space.
Access your crawl space and remove debris, old lumber, and trash.
- Choose sump basin location.
Survey the crawl space to determine the best sump basin location. In general, locate the basin in the lowest portion of the crawl space where water will naturally drain to.
In addition, consider a location that allows for easy access, unit servicing and drain tile connections. For this project, I located the sump at the lowest point in my crawl space, where I had previously found standing water.
- Plan drain tile layout.
Determine the desired area of the crawl space to be drained by drain tile installation. For me, most of the water was concentrated at one end of the crawl space, so I started with installing drain tile just in this area.
I do plan to expand the drain tile coverage over time.
- Prep for sump basin and drain tile install.
Dig sump basin hole and trenching for the drain tile.
When digging, oversize the trenches and sump hole to allow for aggregate placement under and around the basin and drain tile pipe. This aggregate bed will encourage water passage into the tile and sump basin.
You may also want to drill holes in the side and bottom of the sump basin to allow for direct water drainage into (and out of during dry periods) the sump basin. When trenching for the drain tile pipe remember to slope the trench toward the sump basin.
Trench drain tile parallel to the foundation wall, 12 – 18″ away from the foundation. Dirt should not be disturbed next to foundation walls or footings and do not dig under these structures.
Foundation wall forces are distributed in parallel and at angles to the wall and its footings and undermining foundation wall support can compromise your structure and risk structural collapse. Generally, you should stay the same distance away from the footing as the height of that footing.
Contact a structural engineer if you have any concerns when digging in your crawl space — this is important!
- Prep sump basin.
Cut holes into the sides of the sump basin to allow for passage of the drain tile pipes that will empty into the sump basin. I cut these with a heavy duty 1/2″ drill and appropriate size hole saw bit.
You should also check that you can get the sump basin into the crawl space through the access you have. In my case, the access was too small for a full size sump basin. I needed a way to get it into the crawl space, and decided to cut the basin into two halves and re-assembly once in the crawl space.
To allow for re-assembly of the sump basin, I attached 1/4″ aluminum stock and the waste discs from the tile access holes (they work perfectly as their profile matches the curve of the basin) with stainless sheet metal screws to one of the two halves prior to placing it in the crawl space.
You may also want to drill holes in the side and bottom of your sump basin (I did) to allow for water around the basin to easily drain into it without having to go through the drain tile pipe. Drilling holes in the bottom allows the basin to drain if the water level falls below the level of the basin.
- Install drain tile and sump basin.
Lay down several inches of aggregate in the base of the sump basin hole and at the bottom of the drain pipe trenches. Aggregate can be anything from sand to gravel. Smaller aggregates are likely to be more stable, but tend to get into the drainage pipe and sump basin.
I used small river rock and pea gravel, and covered the drainage holes on the drain tile pipe with aluminum screen to help keep the aggregate out of the drain pipes and sump basin (you can also buy filter sock covered drain tile). When installing the drain tile pipe, slope it toward the sump basin and pass it through the basin access holes several inches to allow it to drain into the sump basin.
Once the drain pipe is installed and passed into the sump basin, cover drain tile pipe with aggregate (I used pea gravel) to bring it level with the surrounding dirt.
- Install sump pump.
Place the submersible sump pump in the sump basin.
The sump pump will sit in the bottom of the sump basin and discharge the accumulated water that enters the sump basin. Most pumps are activated by a float trigger and will not pump until the water level in the basin is high enough to trigger this float switch.
Prior to placing the pump in the basin, I attached the discharge PVC pipe to the pump, as this is much easier to do prior to the pump being placed in the basin. This pipe should be long enough to pass through the sump basin cover and allow for connection of a union / check valve.
Additionally, most pump manufactures recommend drilling a drain hole (3/16″) in the discharge pipe, at a level just above the top of the pump (Read the install documents for your pump). The purpose of this hole is to allow drainage of the discharge system after the pump stops.
Prior to setting your pump in the sump basin, you should clean out any aggregate that has found its way into the sump basin.
Once the basin bottom is free of rock and the discharge pipe is attached, simply lower the pump to rest on the bottom of the basin. The pump is not attached to the basin, but the weight of the pump and the plumbing attachments will keep the pump stable.
You may need to adjust the position of the pump once the sump cover is on and the plumbing attached to ensure the pump sits flat on the floor of the basin.
- Attach sump cover and connect sump discharge plumbing.
Pass the discharge plumbing stub throught the sump basin cover.
Attach this discharge pipe to a combination union and check valve (green vavle in photo below) and plumb the remainder of plumbing for the discharge circuit. The rubber fitting of the union / check valve prevents backflow into the sump and provides a break point for the discharge plumbing.
Next, pass the power cord for the sump pump through the basin cover (use supplied rubber seals for the cord) for eventual connection to a suitable power supply. Secure the sump cover with supplied bolts /screws. (Many covers ship with a rubber seal that should be attached to the underside of the cover before attaching to basin top.)
- Install vent plumbing and connect power cord.
De-watering sump systems should be vented and venting may be required by state and local plumbing codes.
To vent the sump basin, I used the same 1.5″ pvc pipe and incorporated a rubber coupling to serve as a disconnect if needed. The vent pipe simply needs to pass through the sump cover and vent the basin to the outside air.
Once both the discharge and vent are in place, run them to the desired point to pass them through to the outside of the house. I ran the plumbing for this project allow the floor joist and through the rim joist to the outside of the craw space.
- Finish ground work around sump basin.
Using aggregate (pea gravel), I leveled the ground over the drain tile and around the sump basin to encouraged rapid water drainage.
- Complete plumbing passing it outside the crawl space.
To pass the plumbing out of the crawl space I drilled holes through the rim joist using a heavy duty 1/2″ drill fitted with a hole saw bit and bit extension.
Once the plumbing was passed to the outside, I added a rodent screen (pvc drain guard) to the vent circuit and a right angle hose attachment fitting to the discharge circuit to temporarily direct discharge water away from the house.
Eventually, I will create a drain system for use with the rain gutters that I can direct this discharge water to as well. To finish, I sealed the passage holes with exterior caulk.
- Connect pump to power supply.
Check the requirements of your pump, but most pumps will require a 20 amp circuit and should have ground fault circuit interruption (GFCI) protection. The GFCI protection can be at the receptacle or at the circuit breaker.
I wired mine with a GFCI circuit breaker to allow for easier re-setting of the circuit if needed. For the 1/2 HP pump I’m using, I wired a dedicated 20 amp GFCI circuit to use for the pump. I also added a utility light for the crawl space from this circuit.
- Enjoy a dryer crawl space. Consider encapsulation of your crawl space.
Switch on your power circuit (if not already on) and wait for the next downpour. Your system should be functional and will operate periodically as the sump basin fills and triggers the sump pump to empty the basin.
With the standing water issue solved, I now plan to encapsulate the entire crawl space with a vapor barrier and active evacuation system to reduce moisture and solid gas emission and entry into our cabin.
As a followup, this system was installed in the spring of 2012 and has far exceeded my expectations! This system pumped out hundreds of gallons of water throughout the spring and summer. I highly recommend the Zoeller M98 pump — it’s quiet, and more than powerful enough to quickly empty the system even during heavy rains.