Cellar floor replacement
I would like to replace my cellar floor. currently the floor is very uneven and a mix of concrete and dirt. I don’t need to increase the ceiling height in the cellar but I would like to put in a nice flat floor so that I can use the space as a workshop. I think that what is needed is removing the old floor, then sealing it up and put in a new floor. Am I correct?
What type of contractor should I be looking for to do a job like this? Any recommendations?
davbrook
in General Discussion 3 years and 10 months ago
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20 replies
dorkofwindsor | 3 years and 10 months ago
cookthebooks – I think you can dig down to the top of the footers. usually an exploratory hole needs to be dug in advance to determine depth and feasibility.
workisfun | 3 years and 10 months ago
Knockout Masonry
andriywww1990 | 3 years and 10 months ago
my aunt has a sump pump. my mother has two sump pumps. ALL of these pumps were put in after the concrete slab was in and these folks later realized they needed one. in a way, from my thinking, it is easier to install after watching where the water settles as that is were the pumps goes. however, a good concrete finisher can slope a floor just enough in the direction of a waste line or convenient place to place a pit and discharge the water. i am not sure how much slope is required to make water flow across smooth finish concrete. 1/16 a foot over 10′ would give you a drop of like 5/8″ . not sure if that would work.
my aunt’s floor was so level that water stood in places like the middle. so the company that put hers in cut channels in the concrete (where the water sat) and they drained into a sump at the back of the house. these channels are covered with something and i forget what, like mortar (its been years but i used to reach into the sump pump pit to clean out plant growth; it was a horrible task and she now pays someone). i do believe this pum p has some sort of battery back up and it recently failed and the entire basement flooded.
the pumps in my mother’s house: the heating system is down stairs and she is against the water on long island. any storm pushes water into her back yard (from a salt marsh, this is not a luxury home) and because she does not remain for these storms, to monitor things, she has one pump on a stand by generator and another is battery operated. i am not sure who situated what where and how they decided to do that (i might be able to ask, she deals with these contractors and she asks a lot of questions and might have been part of the decisions).
one very interesting thing i saw a customer do with a sump pump. most of the basements that require sump pumps need a dehumidifier, even in the dry season. a customer of mine set her pretty big dehumidifier over the sump pump pit so it would drain into the pit and when that pit fills, the sump pump sends the water out through the waste line.
the sump pump should be near the waste line if you can make that work. if not, a proper pump with proper npt fittings can be piped by a real licensed plumber to drain anywhere and backflow valves can be put in the lines so water does not roll back to the sump. we had one on a job once that was piped to a waste line across the building. i am not sure how plumbers make the actual tie in to the waste line as most of these i have seen were on long island and they dump it out on the lawn – sometimes using just a garden hose but if you have any larger sort of pump, it will be a larger line with pipe threads and by the way, when i was first in NYC we needed a sump pump in a building and i wanted to put in one the back of a building with hose that we would have to unfurl when ever it rained and we would sneak it into another building’s lot (they had a giant lot with all sorts of drains) and my boss let me know that in NYC that is not something we do – even if it looks like it is ok to do.
solehappy | 3 years and 10 months ago
curious how contractors determine how far you can dig down before needing to underpin/bench
davbrook | 3 years and 10 months ago
tell me more about the sump pump – where should it be placed? sounds like a good idea
davbrook | 3 years and 10 months ago
Thanks for all the comments. the space is about 850 sqft after I remove the walls, stair well and the boiler room (we don’t want to touch that). I don’t think we want to dig out the space, I have almost 7 feet now. I brought a contractor in and he said they would come in an remove the old concrete floor which is a total mess. they could go down maybe 4 inches and then they would pour concrete in. The plan would be in two stages as we move stuff in the basement from one side to the other. I don’t have a quote yet.
I don’t think we want any floor covering, maybe we would polish the concrete or put down epoxy.
Any recommendations on contractors?
Do I really need to get permits to replace a floor?
kassie319 | 3 years and 10 months ago
My scope was pretty much what Cate described: Remove ~3″ of rat slab/ compacted dirt, install a vapor barrier and 4″ slab. No gravel fill, additional drainage, plumbing or electrical. No work in boiler room or in area beneath two oil tanks so I would say +/-650sq.ft or so.
hasibur.rahman07 | 3 years and 10 months ago
Not to say it can’t be done but really depends on the scope of work. In OP’s case, it sounds like the concrete layer is not consistent so perhaps breaking it up is not as much labor. Pictures would help then it could be estimated by the work required.
andriywww1990 | 3 years and 10 months ago
vard, i ran the numbers using what we paid for concrete to be put down in our lane way and if my lane way were the size of a brownstone basement it would have been $16,000. so not factor in a four days of heavy labor breaking the old floor and excavating a foot down and all those things augustiner suggests (which is the way it should be done, i am sure) and you are correct 20k sounds low. when we consider that labor and the concrete pumping, minimum looks like 30k.
hasibur.rahman07 | 3 years and 10 months ago
It would be very helpful if the estimates listed exact scope of work. 20K is barebones given my experience One has to think about all the other stuff that Augustiner is mentioning: gravel, insulation, barriers, drainage, walls and ceilings, electric etc
Augustiner | 3 years and 10 months ago
Sure you can do it for 20k, but that’s a bare bones job without any extras. Also, Cate and chinatownred forgot the additional 4 inch for gravel inc. digging 4 inch more 😉 you need it to level and avoid cracks. You may want to install a radon fan later which sucks out the gas under the slab, which simply doesn’t work without the gravel layer. I would recommend to test for Radon if you want be in the cellar frequently. Do it in winter on a cold day, you’ll be surprised.
maybe you want to get permits if necessary, pay a reliable guy who doesn’t leave you hanging half way. Clean up, paint the walls, close the coal hatch, put in a door to the front hatch, maybe put in a Sheetrock ceiling or a new cellar door….
kassie319 | 3 years and 10 months ago
I did what Cate describes recently and it was ~20K
didierlc | 3 years and 10 months ago
The estimates seem accurate. We did something similar, including sump pump, lighting, some electrical etc. to make the cellar more usable. Came to around $40k
didierlc | 3 years and 10 months ago
The estimates seem accurate. We did something similar, including sump pump, lighting, some electrical etc. to make the cellar more usable. Came to around $40k
Lurker | 3 years and 10 months ago
That pricing is on par in my experience. Also, if they’re excavating at all you likely have to get soil core samples and special inspections and engineering documents and energy efficiency and final inspection etc. It’s indoors and presuming your building is a rowhouse your doing this work can effect your neighbors. Certainly some people just roll in and get it done without permits and stuff but I would be surprised if you’re allowed to do that and the penalties for unpermitted work are now sizable.
cate | 3 years and 10 months ago
So digging up the existing rat slab, putting in a vapor barrier, and then 4 inches of concrete in a 20×45 townhouse cellar (doing half the room at a time and taking care to not destroy the boiler) will cost 30k-50k? Seriously? Has anyone else had a different experience?
markwalker | 3 years and 10 months ago
We had that done. You will need a concrete specialist not a flooring installer.
You may wind up with a bigger job than you might suppose at first, for several reasons.
To level a floor, they usually choose the highest point and bring the rest of the floor UP to that level. It’s much easier than excavating it. Unfortunately Many old houses are surprisingly lower at one end than the other. So that lvel floor will be closer to your ceiling, especially under soffits etc.
Leveling the floor will also possibly interfere with things that rest upon it such as doors, staircases, drains, pipes, etc.
My advice is to have some qualified peopke look at your space and discuss the consequences of what you want to do. I’m not saying it is not going to work but it can become a big project, and not cheap.
Augustiner | 3 years and 10 months ago
Remove 1 foot = 25 yard.
Put back 4 inch Gravel, then 5 mil plastic foil, wire mesh on top and 4 inch concrete. To finalize pour self level concrete and finish as desired.
While you do this take the opportunity to install a sump pump with 2-3 drains.
About 2 week work for a 4 person crew. Cost somewhere between 30k and 50k
workisfun | 3 years and 10 months ago
If you’re using the space as a workshop, consider insulation below the new floor.