Landscape for drainage - narrow lot

scrapndoodleAugust 20, 2011

Here's a diagram of my house and lot: From August 20, 2011

The house was built in the 1880s in an urban setting with little land. In the 1980s, the entire backyard was set as a brick patio. The brick patio is above the wood framing of the house (for the frame portion, shown in yellow). Because water doesn't drain off easily from our land locked lot, this has slowly caused the sill plate in the wood frame portion to rot. Unfortunately, our home inspector missed this, so we are going to have to take care of the foundation work in the next few years.

When we do the foundation work, we would like to address the water as well. It's our understanding that, if we did nothing for the water but were diligent about keeping the area sealed, the problem might not require additional remediation in our lifetime. But, if we can come up with some modifications that are livable and beautiful solutions as well, we want to explore them.

One suggestion made was a trench drain along the west wall (the wall adjoining the patio) of the house. The problem with this is that it would require permission from our neighbors (running through their planter bed) and permission from our City to run the pipe through the sidewalk to drain at curb (otherwise it would daylight on the neighbor's driveway - not a workable result).

Another suggestion made was a french drain tied into a sump pump, although it's still not clear how we would drain it. (our sewer line runs in the alley on the east side of our property). We have a very shallow crawl space and no basement.

We would be willing to consider a more permiable patio material, particularly on the more narrow area by the frame portion of the house. But I'm not sure if this would help or hurt (if water permiates, where will it go?). For the main part of the patio (approc. 24' long by 7' wide), we would be open to some changes there as well if it would help the situation but would want to make sure we had a stable surface for a small bistro table as well as good pathway out the door, to the back gate, and to the tool shed.

Any creative ideas?

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scrapndoodle

There was a problem with my link. If you click the "August 20, 2011" link you'll be able to get to the picture album and from there a larger version of the diagram.

    Bookmark   August 21, 2011 at 9:20AM
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karinl(BC Z8)

Thanks for clearing up the link; it was refusing access. I may be a little slower than most, but I find I am still unable to fully grasp the problem because I don't see any grading information, not just for your lot but for the neighbours' as well.

Some photos from street level might help to augment the information in the plan view, or just some sketches from those perspectives?

I don't know if some information about your climate (indicating things like rainfall and snowfall) would also help me and others. For me at least, I find I am still floundering in a bit of an information vacuum, and I think those are the major missing items :-)

KarinL

    Bookmark   August 21, 2011 at 8:15PM
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missingtheobvious(Blue Ridge 7a)

Also in the interest of clarification:

If I understand correctly,
East = top (sewer easement)
North = right (back alley)
West = bottom
South = left (street)

Currently, water collects on the bricked patio and cannot leave the property:

= to the sewer easement (east; top of diagram) because your house is in the way/abuts the entire property line on that side;

= to the back alley (north; right side of diagram), because the back alley is higher in elevation than your property;

= to the street (south; left side of diagram), because your house is in the way/abuts the entire front property line.

That leaves the west (bottom of diagram).

What is it that currently blocks water from draining off the bricked patio to the west? Is that neighbor's property also higher in elevation than your bricked patio, or is there a wall involved: and if so, is it the side of the neighbor's house or a wall between the two properties -- and if the latter, is it on your property or his?

Does your house have gutters or any provision for drainage from the roof? Where does the roof water go?

    Bookmark   August 21, 2011 at 9:17PM
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bahia(SF Bay Area)

The new concrete foundation adjacent the brick patio will need to extend above the height of the exterior finish grade by at least 6-8"or what your local codes require for new construction, and also be waterproofed on the outside if you can't provide positive drainage. It would seem as if a new drain line to the street utilizing the adjoining neighbor's planter would be the easiest fix, and could utilize a sump pump if necessary. Or,while doing the foundation work you could run a new drain line below the house to hook into the sewer if your local codes allow storm water drainage to be tied into the sanitary sewer,(many cities don't allow such hookups for new construction). If you don't already have gutters and Downspouts which remove roof water from this enclosed area,you really will need to either dig a dry sump to drain to as far away from all structures as possible, or remove it to the street via a sump pump and drain lines. Do not leave exterior grades higher than interior wood framed walls as a permanent situation as it will be subject to eventual dry rot and termites. Brick over sand paving is already relatively permeable to rain except under heavier rains. If you do have rain off the roof impacting this area, you'll need to address this first, it can't be ignored...

    Bookmark   August 21, 2011 at 9:46PM
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scrapndoodle

Thanks for your replies so far.

Here is some clarification:

THE DIAGRAM:

East = top (sewer easement)
South= right (back alley)
West = bottom (neighbor's fence)
North = left (street)

GRADING:

I do not have measurements but the lot is very flat. It is graded slightly to drain South to North. The area of South (back of house) is built up about 6" or more in places above our property with dirt, gravel, etc. for a parking pad owned by a neighbor that starts past the 4' alley shown on the diagram. The patio is again fairly flat but graded slightly East-West to drain toward the neighbor's yard. Some water does drain but not particularly effectively. Between our yard and neighbor's yard is a wood privacy fence. The slats go all the way to the ground without a gap at the bottom. Also, there are leaves and woodchips in the neighbor's yard next to the fence.
GUTTERS:

We have two primary downspouts. The first is at the SW corner of the frame portion of the house (near where 3'3" is written). This downspout takes water from the frame portion of the house. The roof is fairly flat and runs roughly N-S. We have a concrete splash block that carries water about 2' away from the house toward the fence. When there is heavy rain, it cannot drain to neighbor's yard quickly enough and pools up.

The second downspout is at the SW corner of the brick part of the house. This takes water from the brick part of the house. The roof is a shed roof that drains East-West toward the patio. We experience some pooling during heavy rain here as well.
CLIMATE:

We are in garden zone 7A. Our average snowfall is 14.7". My experience has been we usually get much less (around 5") or much more (closer to 30") rather than close to the average each year. Average rainfall is about 40" with about 3.5" per month.

    Bookmark   August 22, 2011 at 12:08AM
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karinl(BC Z8)

So I wonder if as you wrote this, the same things occurred to you as when I read it. Seems MTO and Bahia were right to zero in on the roof water. Is there any reason why your gutters cannot be rejigged to drain to the east, where I presume there is (or will be) perimeter drainage to the sewer line?

Secondly, without fully understanding site conditions I am not clear on whether your patio slopes toward the house. Perhaps that is also the origin of your problem. Can you put a retaining wall at the lane, going lower than the end at the house, and slope the patio away from the house?

KarinL

    Bookmark   August 23, 2011 at 12:32PM
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Yardviser

I hope you do not mind my reposting the diagram at a larger size so we don't have to jog back and forth.
As far as drainage of the patio

    Bookmark   August 27, 2011 at 4:52PM
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Yardviser

hmmm...scrapndoodle, I think you have my old house! Fortunately, due to a divorce I was forced to sell it, thus solving the problem! (for me, at least.) I am partially kidding, I did have a house with basically the same problem. The repair is quite a tear-out and requires a re-do of sill and part of wall. During that mess, I would consider extending the foundation high enough that it did not permit rot of sill and wall in the future...of course, with all the proper waterproofing, etc.

How can I be delicate about this?....by all means, I am not suggesting in any way, shape or form that you create an unpleasant situation/relationship with your nearby neighbor. But it looks like you have a zero lot line situation and therefore sometimes things require some cooperation between neighbors. You may have legal rights that you're unaware of, but that come into play in this type of situation. Whether you need to assert your rights (if you have them) is an entirely different question than what I'm addressing. But I would be looking at this problem as though I could get some kind of cooperation (hopefully completely voluntary) from my neighbor. I question whether they are permitted to block drainage from your patio. One fact is that your patio must drain somewhere. As your house looks to be on the pline, the ONLY place you can drain is in that narrow strip you're calling the neighbor's planter bed. Where is the back yard of the neighbor on the other side (above) of your property draining? I'm going to guess right down the middle of the 28" wide strip between the houses. One way or the other you have to find out which side of you're house you're legally entitled to drain and then base your plans on that.

Sometimes one must become very creative when solving these problems. And the best solution may depend on MANY factors. As others have pointed out before me, you may have other things (gutters & downspouts, etc.) that may be part of the problem.

If at all possible, I would keep drainage on top of ground rather than in a pipe. Maintenance is easier and failure is minimized. What's happening to elevation at the front of the lot. is there room to bury a pipe and have it empty into the front yard? If storm water needs to go into a pipe, what's your soil like...full of rocks...tree roots, or not. Is it difficult to dig? Boring, while it sounds major, might be one of the easier ways to install a pipe. (I've only personal experience with boring for small diameter pipe, but it was MUCH EASIER than I thought it would be.

    Bookmark   August 27, 2011 at 5:28PM
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