Recommended: Directing water away from the home either through grading or drains.

Not Recommended: Channeling water towards the house or neighboring homes.

Trench Drain. Image Credit LDHP Cynthia J Steward.

Trench Drain. Image Credit LDHP Cynthia J Steward.

Part of the task of keeping water out of a historic building is to direct the water away from it. This is done by keeping roofs, gutters, and downspouts in working condition and channeling water collected by these into appropriate subsurface drainage. Grade the soil so that water drains away from the building. Point downspouts away from the building and onto splash blocks when grading alone is not sufficient. Catch basins, trench drains, or perforated French drains may be needed in some cases. For these retrofits, it may be necessary to consult a landscape architect or a civil engineer who can visit the site to determine the best course of action.

Trench drains with grating covers can be a good option for difficult to drain sites. These differ from French drains in that the bottom of the drainage channel is not

French Drain. Image Credit LDHP Cynthia J Steward.

French Drain. Image Credit LDHP Cynthia J Steward.

perforated. It is possible to empty downspouts into a trench drain. A trench is dug and a drain pipe is laid in the trench to carry water away from the structure. French drain pipes may also be wrapped in filtering fabric or filled with gravel to assist in keeping them free of silt and other debris that will hamper their effectiveness. Drain pipes must slope away from the house and empty into a storm drain, ditch, or field that can handle the additional water. Water should never be diverted toward another structure.

References

Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures (Third Edition), FEMA

Stop Floodwater in the Yard, LSU AgCenter

Additional Resources

Homeowners Guide to Drainage, City of Scotsdale


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