exterior basement waterproofing questions?

I am looking into installing an exterior basement waterproofing system myself. I have two questions though. First I have exterior basement stairs with a Bilco door. How were these installed? do the blocks around the steps go down to the same footer level as the rest of the house? If not where do you run the exterior drain?
Also the water table is pretty high and the lot is almost level according to the perc test. This means I need an exterior pump. Any idea if its the same as an interior sump pump or something different?

 

I would not worry too much about the Bilco system. It is pretty much sealed at the footing and along your wall professionally.
What type of waterproofing are you considering? We consider water proofing as making the basement impervious to water infiltration by external layers of water proof membranes and solutions. From your post it appears you are running a weep pipe system around the house.
Fill us in on your method.
Where is the lowest point of the yard without encroaching on neighbor's property? Do you have a nearby storm drain system installed?

 

So are you saying the stairs have a footing at the same level as the rest of the house? Trying to understand how these stairs are installed.

I am not 100% sure what I want to use. I think I will coat the wall with eco-flex. From there I think I want some type of sheet material. Either one of the dimple like products or a simple plastic adhered to the eco-flex. Then some foam board for protection and insulation. At the footing I would put down some filter fabric and then lay a pipe pitched toward one corner of the house. Then back fill with gravel up to about 18" to 24" from grade level. Put down more filter fabric. Then put topsoil on top.

The lowest area of the yard is the river. Its about 50' from the side of the house and only 2-3 feet lower then grade level at the house. The basement floor is around 6 feet lower then grade level. Which is why I need a pump.

Any thoughts on the plan?

 

So I figured I would update everyone on what I decided to do. It took me a long time to decide what I wanted to do but the hurricane in September really pushed the issue. I was all set to do the work except I didn't trust my self using an excavator around my house. I called up a septic guy I use to wire septic pumps for. I didn't realize it but he did waterproofing jobs as well. Figures if you can install a system to put water into the ground you can install one to take it out. We finally settled on the following:
1. Dig all the way to the base of the footing around the outside of the house.
2. Install a 4" PVC drain all the way around.
3. Set a 2' diameter pipe as a sump pit about 3' away from the house, and about 2' below the footing. Put holes in the side of the pipe and fill the area around it with gravel.
4. Put a sump pump into the pit and pipe the discharge 15' away from the side of the house towards the brook.
5. Apply Tuff & Dri and Warm & Dri to the exposed walls.
6. Back fill with crushed stone over the pipe and then dirt raising the level around the house to provide more of a grade.

We found out two things during this process that made me glad I did it this way. First I have a monolithic pour. The basement floor and footing were poured in one shot, then the block walls were built on top. Busting open the basement floors would probably not have been a good idea.
Second the bilco door was made wider at one point. They kind of just put a little concrete on the side to make it look good but the frost must have been getting under it and pushing things up. We fixed the broke blocks and then built out the wall all the way down to the footing so the frost wouldn't damage it again.

Here is what the door looked like:



Drains installed:


Waterproofing on and backfill started:


Pump pipe:


Turned out to be less of a DIY job then I was planing but I just wasnt comfortable using an excavator next to my foundation. There was some big rocks in there that would have ended up in the basement if I was doing it. The spray stuff seemed like a better product then anything I could buy locally and install myself and the price was about the same. I did get to wire in the pump and clean and repair the foundations though.

So far its worked really well. My dehumidifier stopped running entirely. I'll know better in the spring but so far so good. If I forget remind me to update this.

The number one lesson I learned in this process is the waterproofing companies are big rip-offs. This project cost less then the lowest bid I received from all those companies that wanted to do it inside. Sure its a muddy mess outside but I wanted to redo the landscaping anyway.

 

I do not recognize the insulation boards that you used. Are they XPS foam or is it something else? it almost appears to be rigid fiberglass boards which could be a problem below grade. just curious.

 

Warm N dri is the product: http://www.buildsite.com/dbderived/o...ived238388.pdf
It is a fiberglass board. From what I've read the water should drain through it.

 

thanks for the link. I was not aware of this type of system. it is all EPS foam in our area.

 

That tile system will be a nice improvement. With your situation concerning footing and floor level at same height the bar was raised for you to overcome the water problem. Instead of the water hitting a stop below floor level,It gave the water that followed the wall down to footing level a launch ramp through a vulnerable bottom horizontal block or poured wall joint. That was because the footing that extended beyond the outside of the wall stopped the water at the floor levelinstead of 4" below that as is the case with most basement floor levels. In your situation water could just make it's turn beneath any cracks in the mortar joint voids the block. But you have now created a path of lesser resistance to your tile. I'm sure while you had the chance you saw to it the bottom block horizontal mortar bed was well sealed or even coved.

Good work and I am sure your situation has definitely been improved.

bs5

 

I wanted to ask, how did this turn out? Did it seem to resolve your problems so far? I have the same sort of situation and was thinking about doing this.
I need to find out the cost of having someone excavate. I can do everything else but dig up all the dirt.

 

Sparky -

You really do not have a "monolithic" pour of the floors and walls. You have separate pours of concrete with joints between them. To my knowledge the only thing similar would be floating home in Amsterdam recently in a plant and the old Russian precast units because they rarely used concrete outside a precast plant (few delivery trucks and qualified field placers and finishers).

Any way you cut it, you still have a cold joint (days or weeks apart in construction)between the slab and wall. Definitely not a continuous monolithic concrete structure.

Dick

 

so far so good. This spring has been rather dry so we haven't had a real good test. But the difference since it was done is very noticeable. It use to be so damp in the basement I would need to run the dehumidifier almost constantly. Now Ive packed it up and put it away, every thing is bone dry. Really the excavating and backfill is probably the most work, laying pipe is quick and easy. I dont think its worth applying the coating your self. This spray on Tuff N Dri seems like a much better product then anything you could have applied yourself. Renting a mini-excavator is probably the best way to save money on this project, but it could also cost you a lot if you screw up with it. Let me know if you need any other info.

By "monolithic" I mean the floor and footing were poured together. Usually the footing is poured and then the walls are built on the footing and then the floor is poured on top of the footing. In my case they only form up the outside of the footing, then they pour the floor and the footing together. That leaves the inside edge of the footing kind of undefined. Then they set the blocks right on the floor. When done this way the cold joint between the footing and the blocks is at the floor level instead of lower then the floor as it would be if they were poured separately.

 

"By "monolithic" I mean the floor and footing were poured together. Usually the footing is poured and then the walls are built on the footing and then the floor is poured on top of the footing (Sparky)
================================================

But did your floor/Footing end flush with the bottom outside of the first course of blocks or poured wall or did it extend beyond the corner of the house foundation?

bs5

 

The footing/ floor extended beyond the edge of the block by about 2". In other words they set the first course of blocks 2" in from the edge of the slab. There was a small cove plastered onto that corner to help prevent water from sitting on the slab and leaking under the cold joint where the block mates with the floor.

 

So did you actually physically dig yourself? You said earlier you didnt want to excavate due to possibly screwing up and damaging something.

You posted earlier about not applying the stuff yourself. Id think thatd be the easy part, applying it yourself. And did you end up using Eco-flex at all? The stuff looks really good. Im not familiar with the products you mentioned.

For the drain from you exterior pump, you just ran it underground a way from your house? How often does it run? I dont have a brook or anything near by so Im thinking of digging a dry well 20 feet or so away.

I dont plan on doing the entire perimeter around my house, at least not this go round. I really only seem to have problems on one side and part of the rear of the house where the bilco door is. I figure if I can take care of that, it will help tremendously and Ill finally be able to start fixing up my basement and making it a livable area. Ill be thrilled if this works out. Especially since the Basement Systems companies that want to put an inside system in, want to charge $7k or more.
This may be some hard work, but the most youd pay would be for excavation if you go that route.

 

No I paid some one I knew that was very good with an excavator to do the digging. Initial thought was to dig my self but chickened out. I guess you could try digging by hand but they dumped all types of big rocks against my foundation. There was no way I was getting them out myself. Its not that expensive to rent a mini-excavator. If you have the place to practice, you could do that. Your working in tight locations so you need to be good. One mistake and you could punch a big hole in the wall or break a gas line.

Well initially I was looking at Eco-flex and just rolling it on by myself but my excavator recommended tuff-n-dri. TUFF-N-DRI H8 - Tremco Barrier Solutions
It is sprayed on with special equipment so you cant do it yourself. It goes on very heavy and seemed like a much better product then anything I could roll on myself. I was also having dificulty locating any local suppliers that would carry any good roll on product. I also compared the cost and it was almost the same to have them come out and spray it as it was for me to buy some other material.

Yep we just ran the pipe about 8" underground with a small pitch. Eventually the ground slopes enough that it came out above ground so we ended it there. About 25' from the house. I am not sure if the pump has run yet. No way to tell from inside right now. Ive been thinking about hooking up an indicator light but I haven't. Really the pump will only run once the water table starts to rise to the point it comes into the pit. Right now since it hasn't been really wet the sump pit acts like a drywell. It just gives the water coming down around the foundation a place to seep into the ground below the level of my basement. Do you have any grade at all on your property that you can run the sump discharge out above the ground at some distance from the house? I guess a drywell could work but the sump pit is sort of a drywell as it is. The purpose of the pump is to get the water out when the water table is high. If the water table is high in your drywell where is the water from the pump going to go?

I think that could work. If not you can always keep digging and working your way around the house. But why only the one wall I wonder? Is it the way your property is graded?


Those places are ripoffs. If I subtract the extra I paid for the 2" insulation and the mason work to fix the broken block around the door I paid about that amount for about 100 linear feet of basement wall. I dont understand those inside systems. 1. the walls are always damp. 2. they direct the water inside so they can pump it out. Then they charge you extra for battery backup pumps and things like that because once that thing stops working your basement is filling with water really fast because the water is directed inside. With the exterior system the idea is to keep the water out. If my pump fails water is still going to have a hard time getting in.

 

Sparky67- thanks for sharing your experience.

I also want to do something similar, and I'm in the initial research stage. I'm in a flat land area with a high-water table. I'm hoping a drain pipe around the perimeter would help me.

I have a few questions ?

1. Since, the drain pipe will be about 5-6 feet deep, do I need to use the thick 4" PVC pipe, so that it doesn't get crushed ?

2. Where should the holes on pipe be at ? I've read about a pipe just having holes in the bottom, others at sides only...really confusing..? What did you do ?
Does the pvc pipe come with holes? - I didn't see it in my nearby box stores in NJ/NY area.

3. Did you use a sock on the pvc pipe? used gravel underneath and on top of the pvc pipe and wrap it all with geotext fabric? Or is the sock enough ?

thanks,
Acie66

 

I think its schedule 20 PVC. So not real heavy but not the black flexible stuff either.

The holes should be on the bottom.The pipe comes with two rows of holes at like the 5 and 7 o'clock positions if you look at a cross section of the pipe The lower the holes the lower the water level. Really a lot of the water will probably travel through the crushed stone under the pipe to the pump but the pipe helps open it up some. I got the pipe from a landscape supply. Its readily available, I think the big box stores even have it.

No sock or fabric around the pipe. We put about 6" of crushed stone under the pipe and then filled the hole with probably 3 feet of crushed stone above and around the pipe. We did put filter fabric between the stone and the dirt to help slow the migration of the dirt through the stone but its probably not really necessary. The stone acts like a filter. Try it. Lay a pile of crushed stone on the ground. Then put some dirt on top. Spray it down and then see how far the dirt went into the stone. It actually will only get an inch or two into the stone. Of course over time it will work its way deeper but not very fast. I doubt it will get through all that stone in my life time. I understand that the correct way of doing it is to use a correct mix of different size stone matched to the soil type as the filter. That would require a geo-engineer and lots of expensive gravel. I dont think it would be worth it. some 3/4" crushed stone and some filter fabric should last a long time.

 

Thanks for your reply, sparky67.

It just seems counter-intuitive that the holes go at the bottom of the drainage pipe, but so be it.

Were you able to do everything in one day ? I'm hoping I can do it in 2-3 days, considering that I'll probbaly have to repair foundation wall cracks or at the very least apply a layer of cement on the foundation walls, while I'm at it.

Since I have a sump pump in the corner of my basement, I may connect a pipe beween the foundation drain through the wall into the sum pit. I'm still debating this over putting an external pump outside.

It should be an interesting project, for sure.


thanks for your help.
Acie66

 

If the holes were at the top, you could have 4" of water setting below the the top of the pipe before any would go into the pipe. With the holes at the bottom, the water drains to the bottom and the little bit of pressure it has forces it into the pipe thru the holes where it has a unobstructed exit away from the foundation.

 

No. It took over 2 weeks but we lost like 2 or 3 days becouse of the weather. It takes time to dig that close to the house. I think it was three days for digging and seting the pipe against the foundation and the sump pit. A day to repair the steps. A day to wash the foundation and let it dry. Another day for the tuff-n-dry application. A weekend for that to dry. Then another two days to backfill, run the gutters and sump discharge away from the house and replant the bushes.

Well you would probably have to try to tunnel under the footing. Probably not that easy. The whole idea of doing it outside is to keep the water out. Directing it inside seems like a bad idea, but then again you already have a pump pit inside so you are in a different situation then me.

 

Normally, an exterior pvc drainage pipe (never use the cheap corrugated stuff) is placed level with the invert (bottom) at or slightly below the bottom of the footing and the perforations at 4:00 and 8:00 with several inches of a well draining mix of fine rock and clean sand after a filter fabric is laid on the exterior of the excavated area.

Dick

 

Thanks for the info...

Let me se if I got it right ?

So, I should excavate about 9-10" below the bottom of the footer. Apply a filter fabric on the excavated area, then add a mixture of sand and fine gravel for about 6" depth. Then place the 4" pvc pipe with holes in bottom half of pipe, such that the top end of the pvc pipe is even with the bottom of the footer ? Then apply about a foot of 3/4" gravel or so on top of the pvc pipe and wrap the filter fabric sitting on the excavated area over the one foot of gravel ? Is this correct..

Then I just backfill it.

The mixtire of sand and fine gravel, is it a straight 1:1 ratio ?

I also need to provide a slight pitch so that the water travels to the desired sump pit location.

Did I miis anyhting ?

Thank you all for your guidance.

 

Almost got it. Try to avoid digging bellow the bottom of the footer. You dont want to undermine the pressure area around the footing. I think the recommendation is that you should not dig below a line drawn on a 30 degree angle from the bottom outside corner of the footing. My footing was like 10-12" thick so I just went to the bottom and then stopped.

We used almost 3 feet on top of the pipe. Putting stone against the foundation helps relieve the water pressure so the more the better. Just dont go so high that surface water is directed straight down along the foundation. You only need about 2 feet of dirt on top of the stone to do that.

I am not sure on the gravel sand mix. My understanding was you build a filter by putting the filter fabric down then a layer of sand, then fine gravel, working your way up to courser and courser stuff. Like I said I didn't do this but its probably the right way to go. Also my dirt is mostly sand anyway.

I put no pitch on the pipe. The water will seek its own level so I just set it level with the top of the footing. If you pitch it you will end up below the footing at one end or too high on the other.

I would apply the waterproofing to the footing before installing any piping and gravel. We did not because of the weather we wanted to have some gravel and the pipe in. The top of the footing got a good coating but it didnt really get down the side.

 

Thanks, Sparky67.

I'm a newbie at this, so I'm sure I'll have lots of questions.

I have two sump pumps in my basement in opposite corners of house. I bought house 2 yrs ago and owner said there no water problems....yeah right.. The front sump pump is inactive until the Irene storm this past year..then it was full throttle. The sump pump in the back of the house is highly active year round. It always has water and even today in NJ, with no rain in past couple of weeks, it still has water in sump pump, and it pumps out about twice per day. During Irene, both pumps were active non-stop and I still got 6-8" of water in my basement. I also got water seeping in through the botom 3 feet of basement walls everywhere...That was rather a shocking experience for me.

So, I hope adding fondation drainage pipes and waterproof membrane on walls will help. I also need to cut patio concrete to get drainage pipes up to the stairs. I'm skipping drainage pipes around the stairs in front and back. Too much hasle with sidewalks & patio concrete...

I'm also strongly leaning towards putting an external sump pump.

Anway, thans for your help. I'm sure I'll have more questions as I get closer...I'm hoping of doing this in early summer..I need the high water level to be at its lowest to work better.

Acie66

 

Wow, that's a really bad case. I definitely wouldn't be piping more water into your basement. It sounds like the pumps have a hard enough time as is. You see that's the problem with interior sump pumps. You have a 18" hole in the middle of the floor with nothing stopping the water from coming right into your house. You can only hope your pump can pump it out faster then it comes in. Really not sure an exterior system can solve your problem since you already have the hole in the floor. It definitely would help especially the walls but I dont think it is going to really change the volume of water trying to come in through the sump pit. Sounds like you need a bigger pump to solve that problem. Double check your gutters and make sure they are not piped into the sump. My guess is if you have water now the water table must be really high where you are.

 

I may have a problem getting something like this done due to a small porch in the back. Again, I really dont intend, at least initially, to do around the entire house. The only trouble areas I have are from one side and partial of the back side.

There is only a small foot and a half gap on one side of the bilco door and where concrete is at for the small porch. I wouldnt have a problem tearing up a bit of that concrete but that corner seems to support part of the roof structure.

I also have a sewer line going out the back and I dont know how where it runs once it leaves the back of the house. Though Im more worried about the one side of the bilco door. If Im going to do this, redoing the frame of that door is a must and I have to figure out how I can get that side of it.

 

Do you know if the footing on the porch is as deep as the rest of the house? Its possible it is if it was built the same time as the house. My guess is it looks like it was added later so you may not be so lucky. I definitely wouldn't be ripping it out unless you absolutely have too. If you need to you can temporary brace the roof before you remove the concrete.

Looks like you have a radon fan on the out side of the house. That's just another reason to avoid putting another pump in the basement floor. I think your existing pumps should have a sealed top as well to prevent the radon from getting in.