Go Back  DoItYourself.com Community Forums > Exterior Improvement Center > Roofing, Gutters and All Waterproofing Anywhere
Reload this Page >

Can French drains and downspouts share a common solid line?

Can French drains and downspouts share a common solid line?


  #1  
Old 05-27-15, 11:06 AM
B
Member
Thread Starter
Join Date: May 2015
Location: USA
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
Can French drains and downspouts share a common solid line?

I live in a ranch home that was built in the 1950s. The home is essentially 25'x50'. One short end of my home is at street level with the basement fully underground. The other short end of my home has the basement fully exposed because of the slope of the ground. I have an attached garage that goes directly into the basement.

A few years ago I connected two of four downspouts to 3" PVC at a depth of about 18". It crosses the short side of my house and runs down the long side to daylight into a gigantic rose bush on my property. It has a strong slope of about 1' per 10'.

Recently, I decided to add a French drain; I get a little water in my basement after several days of heavy rain or the spring thaw. I dug it below the frost line (36" near Pittsburgh). I would like to French the short side of my house, tying into the existing PVC that carries the downspout water away. I will have two parallel lines (over-under: one receiving roof runoff and one French drain water). I would like to connect them beyond the frenched part around the side of my house and have them both share a solid line carrying water from the foundation of my house.

In short, can I connect my downspouts and French drain down the line, AFTER the French part, or is it necessary to run two completely separate lines to daylight?

As a side note: the water comes into the basement through the footer. Can a deep French drain fix this (36') [i.e. caused by surface water] or must I dig down to the foundation [i.e. caused by subsurface water]?

Thanks.
 
  #2  
Old 05-27-15, 01:14 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
Received 38 Upvotes on 30 Posts
Generally it is better to have gutter drains separate from sub-surface drains. However, if I understand your situation you want the French drain to enter into a portion of solid (non-perforated) gutter drain in a manner where it will be free-flowing to the daylighted outlet. As long as the entry is such as to preclude the gutter drainage from backing up in the French drain during normal operation I see nothing wrong with your plan.

Where I would object is if you had the French drain and then dropped the gutter drain directly into the French drain. Doing it in this manner almost guarantees failure of the French drain and negating its usefulness.

As for:
As a side note: the water comes into the basement through the footer. Can a deep French drain fix this (36') [i.e. caused by surface water] or must I dig down to the foundation [i.e. caused by subsurface water]?
I have no answer. Maybe someone else can help.
 
  #3  
Old 05-28-15, 12:03 PM
B
Member
Thread Starter
Join Date: May 2015
Location: USA
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
Furd:

Thanks for the input. That is exactly what I want to do. However, I stopped by my local family-owned hardware and spoke with the owner. He said it's never a good idea because under severe conditions water can back up and make a bad situation worse. I have to dig about an additional 40', but it's better to do it right once. (Hmmm.... should I dig down to the foundation?) Back to DIGGING!

Thanks.
 
  #4  
Old 05-28-15, 01:53 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 25,935
Received 1,756 Upvotes on 1,569 Posts
To do it by code in my area they both must be separate to daylight which I did for the new construction of my home. They all ran to a point right next to each other 20 feet from the house. After my inspection the inspector said "now you can tie them together and finish the run to woods". So, my foundation drains and several gutters now share a common 4" PVC drain pipe, non-perforated so not a French drain. But it's worked fine for over 11 years.

I suppose you could have a situation where your gutters provided more water than the drain pipe can handle or if the pipe became plugged which would allow water to back up into your foundation drain. So, I can understand where the code for totally separate lines is coming from.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: