Waterproofing of basement floor - recommendations needed
Hi,
We’d really appreciate any advice about our basement floor waterproofing!
We’ve had our basement flood twice when the city sewer system could not handle a torrential downpour; the rain came down hard and fast over a period of an hour or so and backed up in our shower and through the backdoor from the drain just outside. Unfortunately, our roof rain empties into a gutter at the back of the house and passes under our house into the sewer, so we can’t install a backflow valve, as the roof rain would have nowhere to go.
The last flood destroyed our basement carpeting and now we want to replace it with something waterproof. Right now, the carpet is removed and we have a thinish slab of a few inches thickness that is bumpy in areas and not level.
1) We’re thinking to replace it with porcelain tile with cement board behind PVC baseboard. Are there any problems with this idea?
2) What is the best way to prepare the bumpy slab surface for the tile? Must we level the floor first, which would mean shaving inches from our basement height? Is it possible to jus t grind down the bumps and lay the tile with thinset directly on top?
3) Will the tile look good if the floor is not level, but smooth? We really want a seamless look to the tile, with very small grout lines. We’d like to use 12×24″ or 24×24″ tiles.
4) Do we waterproof underneath the tile? How exactly? With a liquid membrane, or a physical one?
5) Can anyone recommend a good, reasonable contractor or tile installer for this job? We have a couple of estimates but not sure we are in the ballpark.
Thank you!
msre
in General Discussion 2 years and 3 months ago
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workisfun | 2 years and 3 months ago
When we moved in to our home, we had flooding from various sources in the “basement”, which is a legal living space, in our case. Water was coming through the bath drains, floor drain, and sinks (among other places and causes). When we removed the rat slab, we found that a long segment of the main line was backpitched to the stack. Also several cracks along branches. We installed a French drain to sump pump, our second sump. We corrected the back pitch, replaced the broken waste branches, and installed back flow preventers after both bathrooms, at the front of the house, and one at the back where the rainwater drain enters the house. I laid down 1-1/2” insulation, then 15mil vapor barrier, then 1,700 ft of hydronic radiant loops, and then poured a new slab. Couldn’t be happier.
lindaaponte | 2 years and 3 months ago
We used https://www.hrcwaterproofinginc.com/ after our basement flooded. They are amazing and I can’t say enough good things about Ray.
colonialrevival | 2 years and 3 months ago
Instead of adhering directly to the rat slab, I’d recommend putting down some form of vapor barrier that can then have thinset and tile applied directly to it. SunTouch has an interesting vapor proof membrane that also can hold their electric radiant wire, and allows tile to be applied directly on top via a bed of thinset. The installation instructions recommend a layer of cork beneath the vapor barrier to insulate, when applying directly to concrete. I’m considering this for my own basement.
It sounds like you are comfortable with finishing the space to be flood resilient, but I’d recommend you take action to fix the root issues before doing any finish work. If your back drain has standing water it usually means that your house can’t get rid of the water quick enough. I’m not sure on the motivations behind having a shower in the basement but perhaps that is something worth reconsidering as well.
justinromeu26 | 2 years and 3 months ago
lombardi 516-322-9060
i just reread your questions and i looked at the website for superior that roliner posted. if you call them or lombardi, they will not get annoyed at your questions and even if you do not ask them, they will know their jobs so well that as they talk to sell you the job, they may answer them anyway and after they are done with what they have to say, if they have not answered them, ask the questions. they will understand your concern and will respect you.
i know i said above “i can find answers for you” what i meant to say was “but you have to…” you are on the right track to manage something you know nothing about. i really do not know that much about this to suggest brands or types of membrane. i would have to read like you might have to and honestly, i hate concrete and tile work and would rather read about something else – like widget manufacturing or something.
also, i had to call lombardi to verify his number and wanted him to know i was mentioning him here. i told him briefly about your situation that maybe you want something you can clean up easily with something impervious up the sides a little. that might work. as far as pumps that roliner suggested, if the money is there, that may be the way to go. i have family that have sump pumps on long island but they have water issues for several months out of the year, daily. if it were me here, i would just put something impervious up the sides. a good contractor can figure out what you need and make suggestions.
in so far as using the less skilled contractors (they tend to drift into tile work, painting, and roofing because they think it is easy) you can get away with managing something like this (as a contractor i can do it) if you really know the process and what is right and what is wrong and when they are trying to bs you. and then you have to babysit them and when you do they get annoyed. this is because if you stand there telling them how to do things correctly, it will slow them down and cost them money which they do not have in the job because they underbid the job anyway. a lot of times when they get into something they cannot manage in a situation like this, they will walk off the job and you won’t see them again because they know they cannot get through it. they will vilify you though as unreasonable as this breaks down. happens all the time.
i will ask my better half who we used for the entry but i do not think they are into this in a big way to do walls and basements. i think they were more a floor finishing contractor (tiles and rugs) as decorative elements. you have other concerns and potential water.
msre | 2 years and 3 months ago
@roliner Was your flooding due to the sewers backing up, or was it overflow through your walls or floor from water saturation? We don’t have a problem from water through our walls or floor (except for a small area along our wall inside a closet, which we think is from our neighbor’s basement water situation). Our big problem is from city sewer backups, which we can’t control :(. We’ve been totally dry since September, for example. But I may give them a call Superior anyway to see what they can do for us — thanks so much for relating your experience and giving the recommendation.
msre | 2 years and 3 months ago
@HomeInspector, thanks so much for taking the time to answer so thoroughly. Yes, I like to do my research, and this is an effort at that, and yes, I’m one of those “difficult” (or “meticulous”, as one contractor said) homeowners who asks a lot of questions. I figure, if you’re confident in your work, you won’t mind.
Yes, we have a thin slab, a “rat” slab, so what product would we need to self-level it in the low spots if not mortar? Also what membrane do you recommend?
A contractor told us that they can straighten the floor, but that it will not be level from front to back without ripping out the slab and redoing it ($$$), or adding a self-leveling product to it, forcing us to lose height. Does that make sense? I’m thinking they mean that it could be on a slant in places but without bumps. How would tile that is spaced tightly look in such a situation?
Please do send me contact info for the contractor who did your entry and for Chris Lombardi.
Thank you!
msre | 2 years and 3 months ago
@cate I don’t know where the roof water can go if the valve is closed because water is coming in from the street. The shower and backyard drains were overflowing because all the water coming down from our roof was unable to exit via the sewer. In fact, we’re thinking of trying to rig some kind of temporary rain cistern we could divert roof water to, to store it temporarily before diverting it somehow to the back of our yard.
eatshoppaybills | 2 years and 3 months ago
We had flooding in our basement during the big storm in September and we hired John at Superior Restoration to waterproof our basement. The basement was finished, and we ended up tearing up the entire floor, installing French drains, a second sump pump, and a membrane around the entire foundation’s walls. We also have porcelain wood-look tile installed on the floor. The project was not cheap (~$40k in total) but I know that they were the best contractors for the job. So far it’s been incredibly dry and we’ve even seen a decrease in bugs as a nice side effect.
justinromeu26 | 2 years and 3 months ago
someone on here will know something about this but this is not something that a lot of people on here do and the contractors who write on here don’t seem to discuss these things (me included).
first. if you are talking to competent contractors who know and understand this and do this everyday, they should be telling you what (and how it) has to be done. if you have already spoken to some contractors and they cannot answer the questions you posed above, they are the wrong “class” of contractors (you are swimming in the wrong pond and people who swim in the wrong pond – contractors and customers alike – are perpetually unhappy). find those who can answer your questions without trying to evade them and then check what they are saying by going on the internet. (i am a contractor as well as a home inspector; when people call me for wood work, i WANT them to take notes and WANT them to check the internet behind me; that is how i sell jobs; they verify what i am saying). The questions you posed are EXACTLY what i would ask people I were sourcing for a job i know lit tle about. and the answers better come fast (even if they are not in perfect english).
the cement board sounds like the direction to go. miles above the green drywall. i have a leak now where i have some tile on cement board and it has been there for years and the tiles are holding. but maybe someone has a better idea? mortar over lath? or a combination and a course or two of tile up the wall? even though i do not do this for a living, i can find the answers for you. you have to find a contractor that can put two or three options before you and advise you as to what is the best, second best and worst and justify why.
the concrete can be ground down. there are bigger machines for this and hand held stuff. the use of water when doing this will old dust down. also, there are levelers that can be put down in spots to level it out. but again, people have to be careful and use the correct product. regular old mortar, which is cheaper, will not adhere if it is applied too thin as a leveler. some clowns will try to save money by not paying for leveler (they will underbid the job to get it and the plan is to take shortcuts; in the end, you pay with a crappy job). thinset mortar can be problematic if it is applied too thick.
if i were going to level, i would investigate a membrane that can either be over it and under the thinset to hold it all together and help slow movement which could dislodge tiles, especially if you do not know how thick your slab is (some people on here call them “rat” slabs, they are thin, maybe too thin to support a pricey tiling job). don’t guess at this. too many people working in industries like this one “think” or “guess” and i am always telling them “wrong answer, you have to ‘know'” (i am not kidding about this).
we had tile laid in our entryway and they put a mesh membrane down because we did not have what we thought was a thick enough mortar bed (the professional we called TOLD me what had to be done and he knew i was a contractor and knew what he was saying better be spot on because i did go behind him and read after i called someone i knew).
if there is no water coming in from below, i am not sure sealing would add any benefit. but again, if someone has been doing this longer than 6 mos, they should be able to advise you. i cannot advise you here.
Know this: ALL of your questions are legitimate. if you run into people who dismiss you as “difficult” or turn away from you because you ask them what you have posed here, understand that your questions do not make you difficult (coming from a contractor, these are the INTELLIGENT questions you should be asking). first, if you are female and they do this to you, end the discussion right there. but understand, i have been hiring these trades for decades and i am male and they will try to dismiss me as well; when that happens it is because they are not trained in what they do. Incompetent people get that way when you corner them (they will blame you for asking).
Chris Lombardi does a lot of tile work. people say he is expensive but if you were to call him, you would understand when you talk to him that this is WHAT he does for a living. if you can’t find his number and want it, ask.
do not shop for the cheapest contractor for something like this unless you want headaches later.
steve
brownstonehomeinspection.com
cate | 2 years and 3 months ago
My understanding of a backflow prevention valve is it won’t stop your storm runoff and sewage from flowing into the city sewer, but it will stop water from the city sewer flowing back into your house.