Need waterproofing input

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Posted by: from Pefferlaw
4/4/2016 at 9:36:17 AM

The house is 100 years old. We dug the ground outside to reveal the wall to waterproof but it turned out there is only like a foot or two of flagstone acting as a footing to hold the house up (meaning there is no wall to apply a product to). Behind that is a crawlspace about 20 odd ft long to an inside wall.

The question is as follows.

1: There is no way of waterproofing the outside and has to be done from the inside by busting the floor and putting perf pipe in with stone into a sump and then parging the wall (meaning filing in the cracks) correct or not true?.

2: By digging the outside you would be ruining the integrity of the structure on the house by releasing pressure on the dirt holding the flagstone footings correct or not true?.

3: Is there some new product out there to waterproof the outside of the house when there is no wall to apply the products to?

4: When water has been penetrating the house for over 5 years hydrostatic pressure builds up under the floor and can cause the floor to crack at anytime and there is no way to predict when this could happen or even how it could correct or not true?

I appreciate your input in this matter and if you can follow the format for me to understand that would be great.

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Date/Time4/4/2016 at 11:00:49 AM

Keep in mind that I have not seen the home however if it were my house:

1) Remove the perimeter concrete inside the crawl space.

2) Dig a shallow trench of 10 inches down around the perimeter where the concrete was removed.

3) Install weeping tile with its slope to a sump pump.

4) Attach the dimple board to the foundation walls making sure it is long enough to meet the weeping tile.

5) Use a vapor barrier over the weeping tile such as the dimple board. Place fine gravel over the tile to act as a filter. Replace the concrete.

6) If the center of the floor is heaving then make a weeping tile run to that area to relieve the water pressure.

7) Wall cracks / holes should be repaired on the outside.

Your basement will be and stay dry after a proper installation has been done.


Edmonton Waterproofing

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Eric in Pefferlaw
Date/Time4/4/2016 at 12:29:13 PM


There is no way of digging in the crawl space as it would be dangerous to the structure. Can you answer the questions I posted? I understand what your saying its as the proper way of doing it.

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Date/Time4/4/2016 at 1:10:25 PM

The issue of water pressure and be controlled a the foundation line or 2 to 4' to the outside of it.

Option 1 ) dig no more than 4 feet long (to avoid structural risk) at a time. minimum wide posible 4, 5" as deep as needed. place EPDM sheet agains the stone wall and then fill the gap with medium density spray foam insulation 2 lb/ft3. this will help to keep the structural presure over the foundation wall and 2 provide thermal insulation to the craw space and house. repeat the system 4' at the time. This is the way used to dig holes beside existing buildings.

Option 2. dig a trench around the house 2 feet away from the exterior wall and using EPDM waterproof all the way from the wall to the trench and go a food deeper than the level of the foundation. you will need to put a draing at fill the trench with gravel. What you are trying to accomplish is to avoid water penetration 2 to 3 feet away from the house. I need to sketch something for you. to explain it better.

If you have any more info please free to text me at 604 836 6323 or email


HerNan Alvarez B.Arch, MBA

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Eric in Pefferlaw
Date/Time4/4/2016 at 4:19:26 PM

I know the fundamentals of waterproofing but if someone can explain the questions I asked, that would be great.

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Date/Time4/5/2016 at 12:21:44 AM

1. side way drilling under house and install drains to an outside sump pump

2. yes

3. not yet, if I understand what your saying the foundations are just dirt and stone

4. true

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Date/Time4/5/2016 at 10:11:55 AM

If I under stand this correctly:

1: Floor and pipe correct, parging NO, this will prevent water from escaping freeze/thaw and break rocks.

2: digging outside True, but also a waste of time the foundation is not deep enough to prevent water from entering.

3: Yes and No, most of the time 6mm or more plastic, some newer stuff is out there, google crawl space waterproofing (images) white plastic.

4: Yes. However the idea is to have a dirt floor below grade in a footing no below the frost line, covered with plastic and a sump to clear the water and stop vapor from rotting your wood house. cement for slab on grade construction. The idea is to control water not fight with it.

Hope this helps.


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