Draining outdoor shower / foundation?
I’m adding an outdoor shower to a vacation home, which is less than 10 yrs old. I’m looking for advice on protecting the house/existing foundation from the drainage of the new shower.
Existing:
The existing (concrete) foundation and footing appear to code (highly likely given the builder’s reputation), with fabric covering gravel out 4′ from the footing, sloping away from the foundation. I’ve excavated down to the fabric (about 22″ from grade), and the exterior foundation shows the original waterproofing. The existing crawlspace is very drive, despite pacific northwest winters. I haven’t dug down to the footing, but assume that it is there. The soil is generally soft clay. There is flex pipe running underneath to drain the rain gutter, but I don’t know if that is perforated for the drainfield… but I assume that it is.
My plan is to fill this area (8′ long, 4′ wide and 22″ deep) with 5/8″ gravel and lay pavers on top of it. Given the volume (48 cu ft) I’m assuming that even long outdoor showers will drain adequately into this space (through the gaps in the pavers) and then percolate down through the existing rock/fabric, into the perf pipe, and on out into the yard.
1. See any problems with my plan generally?
2. Specifically: Should I add additional mastic or other waterproofing to the foundation exterior wall “just in case” over the existing waterproofing? rubber sheeting starting with a ledger above grade and extending down the 22″ to the cloth layer over the drainfield? Or just leave as is, and hope for the best?
Thanks in advance; any comments, advice or flames welcome!
Replies
Hi David,
I would not add any additional water that close to the foundation. I seems to me that the excavation in clay type soil would form a pool for all water sources to gather.
I'd try to catch the shower water and drain it away from the house to a similar area in the yard away from the house. More work at first but why risk a wet foundation and all of those headaches?
Good luck
Garett
David,
Did something similar on my outdoor shower. I have a 16' x 16' patio with a 4" - 6" sandbase under brick pavers except at the shower. This area(aprox. 4' x 4') consists of a 2" sand base sloped to the center for drainage (think pre-slope for indoor shower pans), 2 layers of 6mil poly with 3" of pea gravel, filter fabric, 2" sand base and pavers. The poly follows the contours of the sloped sand base to essentially create a 4' x 4' shower pan. I put in a 4" drain and connected this to a 4" perforated pipe that slopes away from the house to a crude drywell: 3'D x 2'W whole filled with rocks and covered with filter fabric, topsoil and lawn. Has worked okay so far.
I'm not sure you want, or need such a large collection area that close to your foundation. I would think you want to channel it away.
Edited 8/20/2005 11:02 am ET by TGNY
Edited 8/20/2005 11:03 am ET by TGNY
Thanks guys for the feedback.
There is excellent existing drainage immediately below the 4'x8' area of the shower, given the fabric/stone/perf draining away from the house.
I think what I'll do, given your input, is establish 6mil plastic "sides" for each of the 4 dimensions, so that the water will be encouraged to flow straight down into the existing stone/perf to drain away. Kinda like a 22" high shower pan!
I'm also going to re-waterproof the exterior foundation wall in this area, just for additional insurance behind the 6mil plastic.
What size stone would you recommend for the "22in shower pan"? Unlike your approach TGNY, my plan is NOT to use sand for the pavers, but put the pavers directly on the stone. I don't want anything to slow the draining of the water...
Thanks again!
David.