Sunday, 27 July 2014

Interior Weeping System: Day 1 - The Plan and Chipping Out a New Sump

When it rains, we get water in our basement.  It has been manageable but it's pain.  Day 1 was all about chipping out a better sump.  You can skip ahead and read about chipping the trenches or installing the Waterguard by clinking the links below.

Day 2 - Chipping out the perimeter trenches
Day 3 - Installing the Waterguard and Membrane
Day 4 - Plumbing the sump
Day 5 - Concrete pour!
Day 6 - Membrane and lower shelf
Day 7 - Final shelf and panelling


The usual disclaimers apply -- I'm not a professional and this is total Do It Yourself (DIY) project.  Seek professional input prior to attempting this project.  It is NOT an easy project and requires a significant amount of work, knowledge and capability.  Make sure you fully understand all relevant design, structural, and geotechnical aspects, including the building code and applicable bylaws prior to starting.  Any doubts, hire someone qualified :)  We've had good success (so far), but that isn't a prediction of success at other sites.

The Setup 

Our basement is founded directly on bedrock, with around 1-2" of parging to level to floor.  On one wall, the bedrock actually encroaches inside the house, and during rain storms, water flows through the bedrock fractures and into the basement.  It pretty much negates exterior water proofing unless I want to spend a significant amount of cash.  When it really rains, the hydrostatic pressure builds up outside the foundation wall and water seeps in as well.

Photo of the bedrock:

The previous owner was a bit of a hack and while his waterproof parging on the bedrock and levy directing water to a small inadequate sump works to some extent, the parging is failing more and more with each rain storm and the problem seems to be getting worse and worse.  After a really big last rain storm and the most water to date in the basement, we decided it was time to implement our master plan.

Research and Planning

I researched products and techniques for interior water proofing.  I called 5 contractors, 4 of which came to see the house and provide quotes.  Of those 4 contractors, 2 had no idea what to do although one in particular really pretended he did.  One guy proposed a solution I was 100% sure what do absolutely nothing.  One guy set out to fleece me from the get go.  Of the original four contractors, only one returned a quote.  They had a great plan but unfortunately for them, between the original site visit and the quote, we found a few leaks in the roof and any extra cash we might have had got re-allocated to a new roof.

My original thoughts:

I do need to thank one contractor who planned on a making usable space with a small wall and bench. He didn't get me a quote which is too bad, but the rain isn't stopping so I'm moving forward!  Here is my bad attempt at showing the new "bench" I will create.  Eventually, I will create a second bench higher up, and we'll have built-in shelving (if only a tiny bit awkward)

Step in, which sells Waterguard.  The owner Ray also replies to emails quite promptly.  I selected Waterguard instead of a traditional perforated piping because of what I hope will be savings in terms of my time and less effort for installation.

For example: given that I will have to chip out the interior trench around inside of the perimeter walls, using Waterguard requires only a 4" deep trench as opposed to say a 4" perforated pipe which would require a deeper trench (to allow for granular cover over the pipe). For Waterguard, for a 10 m [50'] x 0.10 m [4"] deep x 0.15 m [6"] wide trench, I calculated that to be around 520 kg of stone assuming a bedrock density of 2,220 kg /m3.  This is bedrock I will have to chip, load into buckets, carry upstairs and dump in a dumpster.  If I went with a 4" pipe and a 6" x 8" trench, I was looking at around 1,040 kg.  Right off the bat, saving 520 kg of material to be moved made the extra cost of Waterguard worth it in my mind.

The manufacturer, sent me a detail on how to incorporate a membrane I had planned:

Chipping Out The Sump

The original sump was small and inadequate.  To kick this project off, I chipped out a larger well for the Flood-Buster sump which I currently have on order.

Original sump, maybe 8" deep and 12" in diameter:

I marked out the new sump, which will be around 18" square on top, 20" deep and a 13" round bottom. The manufacturer indicated the hole should be 4" wider all around, so the new sump was actually marked out at 22" square on top so there would be room for 3/4" clear stone.  I used a 65 lbs breaker.  Quite a beast but very effective.

I drilled the perimeter with 5/8" holes to 12" deep using a SDS max drill.  I thought that this would help to keep the sump from chipping inwards as I went.  In the end, I'm not 100% sure it was worth it.  The 1" chisel bit on the jack hammer was faster and easier.

A quick video of the chipping.  It's hard to keep good posture, especially as the sump get's deeper and deeper.

The drilling in the picture above took around 20 minutes.  The chipping in the picture below was around 5 minutes!

After getting started, it was just a matter of taking out around 4" lifts of bedrock rock.  The top 12" or so was really weathered and went quite fast.

You can see the sump pit progressing.  At around 12" deep, I started tapering in the sump so I would have less material to remove.

The sump is done!  Total time was about 9AM to 1PM, with 20 minutes for lunch, and a few stretching breaks.  I really didn't want to get hurt using the jack hammer.

With the sump done, I turned my attention to starting the trench along the inside wall.  I didn't plan on doing too much of the trench but I wanted to see how hard it would be.  I marked the trench along the wall, and also where the Waterguard discharge pipe will enter the sump.  I put a piece of electrical tape 4" high on the 1" chisel blade so I knew when to stop chipping.

The part went *really* fast, the top part of my floor can almost be dug by hand once you get through the top 1-2".  The 65 lbs jack hammer was really overkill for this.  I learned that this part should go well, but a smaller jack hammer is needed, I think the 25 or 35 lbs jack hammer.  Otherwise I could see myself getting really exhausted constantly moving the large jack hammer to make all the holes.

At this point, I stopped and cleaned up.  The sump took 3 hours or so with the large jack hammer. I'm really glad I had the big one.  Trench took 10 or 15 minutes.

Read about chipping the trenches or installing the Waterguard by clinking the links below.

Day 2 - Chipping out the perimeter trenches
Day 3 - Installing the Waterguard and Membrane
Day 4 - Plumbing the sump
Day 5 - Concrete pour!

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