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High water table - new sump? french drain? other advice?

Posted by eoren1 (My Page) on
Thu, Jan 28, 10 at 15:54

We recently purchased a 1940's colonial in Massachusetts. We have a kitchen and basement remodel planned/in the works. A few days ago, I learned that our neighborhood has a high water table and that most homes have sumps running all day. At least 3 houses on the next street over have had french drains installed with success at reducing the sump pump on time and resolving the occasional flooding issues.
We demo'ed the basement yesterday and it actually looks pretty good without effluorescence on the walls and minimal amounts on the floor. No evidence of mold or major water leakage on the wall panels that we took out (they have been there at least 40 years). The sump runs every 5 minutes because of a very stupid design - small bucket without holes. Basically, the water fills from the top and is emptied out but it never actually empties very much.
Current plan is to install twin sump pipes and larger buckets that have holes throughout.
The basement is going to be finished with 2 inches closed cell spray foam on the concrete walls and dricore on the cement floor.
Wondering if anyone thinks a french drain would help in this situation. We had planned on digging up most, if not all, the vegetation around the house anyway. Seems like a good excuse to dig a bit deeper and drop in a pipe and sand if that would help matters.
Looking forward to your thoughts.
E


Follow-Up Postings:

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RE: High water table - new sump? french drain? other advice?

Don't limit yourself to footing drains. At the least, use a Delta MS (or equivalent) drainage membrane.

Don't just dump sand on the footers. Set on a filter fabric on coarse gravel and cover with at least two feet coarse gravel, followed by a filter fabric, then the sand or other loose fill and capped with clay, if possible, then topsoil if you're planning on sodding.

Ground water can take some odd twists. Up the street, a neighbour runs a sump pump 24 hours. I built and lived in the house literally 12 feet away and never had a groundwater problem.


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RE: High water table - new sump? french drain? other advice?

Thanks for the recommendation Worthy.
I'm wondering if we are just as lucky with this house in comparison to the neighbors. However, I would hate to see the work of finishing the basement be wasted with the first major storm. I'll take a look at the cost of digging down to the foundation and putting up the Delta product.
E


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RE: High water table - new sump? french drain? other advice?

Delta MS will not address your water table. My recommendation is the following. french drains. not the 4'' ads pipe its crap. Use 3" pvc perf. and 16"w by 26" deep poly sump pits. my rule of thumb is one pump and pit per 100 feet of footing drains. Sump pump of choice is a Zoeller. if you have a block foundation weep holes should be drilled. Now my method is a very old one and reliable. This is more a water management system and if maintaned well your basement will stay dry.

If your hire a reputable company a job which i described should only take a few days.

Here are the downsides to anything down on the exterior. first is the price. if this product isnt covering every square inch its a waste of your hard earned money and most the time the guarantee isnt worth the paper its typed on. Also any exterior work is going to be very extensive meaning, and landscaping will have to be removed, decks will have to be taking down, porches will nedd to be removed and re built, the list goes on and on. Now the dangers. removing all the earth around your home down to your footing and pushing it all back in when the job is down can result in the basement walls caving in and your home collapsing. A lot of these waterproofers who do the exterior stuff almost never tell the customers about these facts. I know from experience, it happened to us when we used to do the exterior drains. its just not worth it.

As for the pumps in your basement you can set them high so they only pump when they have to.

Hope this was helpful to you. good luck in your new home


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RE: High water table - new sump? french drain? other advice?

Delta MS will not address your water table.

The OP sees no signs of significant water problems. If there were, it would be advised to go further than suggested by treating the wall with a spray or peel and stick membrane and/or crystalline treatment etc. with special attention to the cold joints followed by Delta MS or equivalent. Or going further and removing the basement floor, and installing weepers under it, a membrane and then sealing.

Drilling holes in the foundation to relieve hydrostatic pressure on the walls does nothing to stop deterioration of the wall; it does nothing to divert water, nor does it handle water that may come in from other new cracks and imperfections in the foundation. When I see building scientists recommend such a method, I'll endorse it.

removing all the earth around your home down to your footing and pushing it all back in when the job is down can result in the basement walls caving in and your home collapsing.

Only if you have a complete idiot doing the job! (Not unknown!) But how do you think a home is built in the first place? The foundation is freestanding, a house is built on top, then the foundation is backfilled.


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RE: High water table - new sump? french drain? other advice?

Thanks for the post and the link - looks like you guys do a great job with waterproofing foundations!
At this point, I am at a bit of a loss as to whther I need to waterproof the house or just replace a sump. We have taken the wood panels down and the asbestos tiles off the floor. I see minimal efflorescense and no signs of repeated/major water damage in the panels that were taken out. I have the previous owner's assertion that they had water enter the basement 4 times in the past 40+ years and not to a great extent on any occasion. I also know that we have a high water table in this neighborhood.
Looking at the house, I see that the grade of landscaping around the house needs to be fixed (it is level at best; downward towards house on the sides). The downspouts point straight down without any diversion away from the foundation. Given these obvious areas for potential of increased water access to the basement, I'm frankly surprised that the basement doesn't show signs of repeated water infiltration or any cracks in the cement.
I'm inclined to put in dual submersibles (one at 3" depth; other at 4") in a slightly larger pit as recommended by my plumber. Then get a landscape crew to pull up all foliage around the house and regrade. Then get the gutters redone/extended away.
I would appreciate your thoughts on whether this sounds reasonable.
E


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RE: High water table - new sump? french drain? other advice?

I would go with your plan. It would be different if your foundation showed more signs of water, but why not try the asy and least expensive things first.


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RE: High water table - new sump? french drain? other advice?

Hi eoren,
I hope your basement project is going well. I also live in Massachusetts (just north of Boston) and our basement sounds similar to yours. We got water (up from the ground due to water table) during the spring flooding (who didn't!?) and supposedly it was the first time the house had flooded. We've lived there 13 months. Anyway, the basement had been finished with wood paneling. I don't like wood paneling but it did look nicely done. My husband ripped it off most of the walls (there was an extra dividing wall in the basement to make a small room, so there was extra wall space to contend with). We're still trying to decide what to do with the walls. Anyway, I know from our home inspection that the tiles on the floor are most likely set with asbestos adhesive. Knowing that, I feel that we have to proceed as if they definitely are asbestos. I don't want to hack away at them, hoping that the home ispector was wrong. (It wasn't his job to test for it, he just warned us that it was likely.)So, I'm hoping you can tell me how you removed your tiles? What was underneath? Last night I had the idea that we should just concrete over the floor but that may not be the best plan. Any advice from your project would be appreciated. Thanks!


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RE: High water table - new sump? french drain? other advice?

Hi Dwysky
Here's what we ended up doing. The basement was asbestos tile flooring with wood paneling adhered to the concrete walls. I sent a piece to a lab to confirm (it had 1% asbestos content) We had the asbestos tiles removed ($1900 for 500 square feet) and took down the wood panels and minimal framing. The black adhesive remained in place but is asbestos-free. We then reframed the entire basement and put down DriCore flooring. This serves to elevate the floor in case of some water coming in. Used closed cell spray foam insulation on the walls (which will not be bothered by moisture and does not sustain mold growth). We had berber carpet glued to the DriCore without padding in case of water getting in. We also replaced the old pedestal pump with twin submersible sump pumps. The sump hole was enlarged and the new buckets have holes throughout to pump somewhat more efficiently.
During the spring storm, we had about an inch of water penetrate the wall facing the front of the house and it remained under the level of the DriCore flooring. Haven't had any water enter since (knock on wood). There is a lot across from us that is being developed and they dug down to check the water table...hit water after 6 feet! No wonder our sump is working so often.
The basement looks great now and is in constant use. Good luck with yours!
E

ps - you aren't in Marblehead are you (that's where we live)

Here's a 'before' shot

I'll post an 'after' when I get the chance


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RE: High water table - new sump? french drain? other advice?

Hi Eoren,
Thanks for the info. Your basement looks very similar to ours! Our floor is not laid out in a pattern, the tiles are all the "reddish" color (with some other shades mixed into the blend). I hadn't thought of sending a sample to a lab, that sounds like a good idea. Part of me just wonders if we can just leave the floor as is, but it's probably not a good idea. Now that they've sat in water a bit, some of the edges are looking worse for the wear. As for walls, I'm now looking into Zen Wall, which is a foil lined inorganic wall panel. It will be great to see your finished photos when you get a chance.
We live in Medford, talked about going to Marblehead this weekend to walk on the beach! Thanks again for the advice, good to know that others are in the same boat. I actually thought we were going to need a boat when we first flooded!! Good luck with the finishing touches.


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RE: High water table - new sump? french drain? other advice?

I wrestled with the idea of leaving the floor as-is and placing the DriCore over it. Asbestos in tiles is unlikely to become airborne. My main deciding factor was that, at resale, I would have to disclose that there was likely asbestos in the basement. It only cost $2000 now (vs lost sales later) to completely abate the asbestos and allow me to say the property is asbestos-free. Any future buyers are likely to have kids and so it made sense to get this done now rather than trying to do it later after having finished the basement. If you need a rec on the company that did ours, let me know.
E


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