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pvp
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Posts:7
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| 08/29/2008 2:29 AM |
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I am in the process of renovating a 60's ranch bank house in NC to meet the energy star rating and use alternative energy. The front of the house has a higher grade sloped towards the house and a water drainage and infiltration problem, so I am digging along the front down about 3' to the footing drain / top of footing to waterproof the foundation with polymer-modified asphalt, line with 1" EPS styrofoam for some insulation, then cover with a rubber membrane. I then will run a new perimeter drain at the bottom of the trench (and replace the bad gutter drains), then backfill the full 3' with washed pea gravel so that any water reaching the front of the house will go straight down and drain through the two pipes (the new perimeter drain pipe and the existing footing drain pipe) before hitting the foundation. However, I am concerned that gravel will substantially increase the frost depth to below the footing and the potential of adfreeze to crack the foundation or shift the footing laterally. Also, the other side of the foundation is an unconditioned crawl space with dirt, so I cannot excavate and backfill it with gravel to equalize both sides. Am I overly concerned? Are there any problems to my approach? Thank you.
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EPSFOAMCENTER
Registered Users
Posts:18
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| 08/29/2008 10:40 AM |
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| Using eps is a good way to go because it is a stable factor in the ground. The department of transportation actually uses this type of product for bridges, highways, roadways, and new road designs. If you need more information feel free to let me know and if you did not purchase your eps yet i can help you with that too if you would like. |
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pvp
Registered Users
Posts:7
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| 08/29/2008 10:56 AM |
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I have purchased the DOW 1" Scoreboard. I considered 2" but thought that it was excessive, but the work has not yet begun so I could add another 1" but stagger the boards to seal the gaps if that is warranted.
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alaskabuilder
Registered Users
Posts:14
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| 08/31/2008 3:54 AM |
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Simplest and easiest is to add dimple board after taking all other standard waterproofing measures - google dimple board or air gap membrane. SuperSeal, Delta, Polyguard are some names I remember... Price varies by total gallons per hour relief, compressive resistance, etc. Amvic and other ICF manufacturers usually have good tech bulletins on waterproof (not water-resistant) foundations. Backfill with pit run and cap the top with 12" or so of clay or other low-permeation local soil.
Proper use of dimple board means the only reason for using any kind of self-draining soil is to avoid direct pressure on the foundation from water expansion (of clay, for ex.) or frost expansion - that's a soil problem, not a water-in-the-foundation problem.
If you properly install dimple board then your next weak link will be the french drains - if I remember the data correctly, average dimple board will drain 15-20 gpm per foot of width? so you should be able to run 10 sprinklers next to the house and the membrane will drain it before head pressure ever builds to the point where water will penetrate the foundation. Anyway, if your french drains will not remove a sufficient gpm or if you do not properly protect them with geomembrane to keep them from clogging, you wasted all your waterproofing money and time...
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Klorinth
Registered Users
Posts:23
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| 09/13/2008 6:14 AM |
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All the advice so far sounds pretty good. Only remaining question is related to risk of frost heaving...
Seems to me the easiest thing to do is to use your EPS to create a skirt along the foundation. Backfill most of the way with the gravel then lay a stip of EPS along the foundation perpendicular to it. If you use at least 2' wide sheets you will help to move the frost line out away from the foundation. The wider the sheets, the farther from the foundation the frost line will get. This can also help with water drainage if you angle the EPS away from the foundation and finish the back fill with a gravel layer on top.
Google Frost Protected Shallow Foundations...
Good luck |
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Brawler
Registered Users
Posts:11
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| 09/14/2008 1:17 PM |
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Pvp
I have a ranch in NC with the same situation. The previous owners put in a french drain with waterproofing years before we purchased our house. When we first moved in we had a river in the basement every time it rained. Instead of excavating near the house i simply swalled the dirt away from the house for about 6' and solved 99% of the problem. If your slope alows it i might try to prevent the water from ever getting within a few feet of your foundation. French drains are great backups. Hope you have luck. |
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pvp
Registered Users
Posts:7
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| 09/16/2008 12:20 AM |
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| Thank you for the responses. I ended up using the polymer-modified asphalt (seems to be a liquified equivalent to dimple boards) and 2" EPS. I also added 1" of EPS perpendicular to the foundation along with 3 layers of filters for the drain system. The local inspector commented that the EPS was unnecessary given the average temperatures, but I feel the minimal cost was worthwhile. |
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