Concrete basement floor - advice? - PeachParts Mercedes-Benz Forum

cornblatt · #1 06-07-2009, 08:40 PM

I have a concrete basement floor that is ~95 years old. It resembles the surface of the moon; it's lumpy and uneven. The 'craters' range in diameter from 1" to about 1', and their depth is between 1/2" and 3/4".

In addition to being unsightly, it's impossible to keep clean because the pits trap dirt and little bits of concrete grit, and it is not pleasant to walk on. I would like to smooth out the surface to address these issues.

The local concrete specialty shop recommended a self-leveling compound (this one: http://www.mapei.it/Referenze/Multimedia/NovoplanEasy_TDS_EA.pdf) but it is $24 per bag, and I'd be lucky if a bag will do more than 10 square feet. For an 800sf basement, that's about $2000. Plus, the floor is not level from end to end, so when I dump in the $2000 worth of leveling compound, it may all end up in one corner of the room. And, it doesn't appear to be marketed for use as the final floor finish; they say it is just an underlayment. The products that are marketed as a final floor finish are twice the price. So, I think this is not an option for me.

Someone else suggested that I make my own sand mix (1 part portland cement, 2 to 3 parts sand) and just trowel it on. This would be less expensive, and the surface would only be as good as my troweling abilities, but it would probably do the job. I am not sure if it would be strong enough in areas where it is thin though - I don't want it flaking off if it doesn't bond well to the existing concrete.

I'd also like something that provides a bit of a moisture barrier (it's not damp to the touch, but if you leave a cardboard box on the floor for a week or two, the cardboard gets soft). A third person told me that there is some sort of penetrating sealant product you can paint on, but they didn't recall the name of it.

Do you guys have any thoughts or ideas on how to tackle this project? I don't want to spend a lot of money on it (a few hundred $ max) because the basement is dumpy and only used for storage. The ceiling is too low to ever turn it into a usable living space.

Hatterasguy · #2 06-07-2009, 08:53 PM

I'd paint it with some epoxy basement paint and call it good. Thats what I did to an old house I sold last fall, it came out pretty good. Cost me $150 and a days work. Roll it on heavy, don't be shy.

The only way to really fix it is a ton of work. Jackhammer the old slab out and pour a new one. My uncles partner did it once on a house in West Haven, its horrible work.

If you get water in the basement, no paint or sealer is going to fix it.

t walgamuth · #3 06-07-2009, 09:08 PM

The dampness will make it tough to get paint to stick I think.

Although its a lot of work I would advise breaking out the old concrete, leveling the earth, putting down visqueen vapor barrier and wire mesh and pouring a new floor.

If that concrete is really 95 years old (I doubt it) it will probably break out pretty easily. Get a large pry bar (6' or so) and start in a soft spot and just get under the slab and pry.

You will spend mostly labor here but you will get a new floor and a vapor barrier. It will add value to the house too.

mpolli · #4 06-07-2009, 09:22 PM

I wonder how much to grind it smooth? That's a pretty big area. You might get a quote on busting it out and repouring. I don't think I'd want to do that myself.

pawoSD · #5 06-07-2009, 09:27 PM

I'd bust it up and re-pour (myself)....might be icky work, but the smooth nice end result would make it all worth it.

t walgamuth · #6 06-07-2009, 09:42 PM

Quote:

Originally Posted by mpolli

I wonder how much to grind it smooth? That's a pretty big area. You might get a quote on busting it out and repouring. I don't think I'd want to do that myself.

I bet it would cost more than digging it out and replacing all the concrete.

jt20 · #7 06-07-2009, 09:43 PM

dry-loc is one of those sealant /paints.

Personally, if I wanted to finish the floor in the future, I would set up a matrix of level strings across the floor and determine my high and low spots with respect to the overall tilt of the entire floor. If the entire floor has a natural slope to it... leveling it is out of the question.

But this would help you do what T Walg. suggested: Take out the high spots, and fill in the low spots according to what your future plans are. If all you want is to paint it, getting one that sticks will make cleaning the floor and its imperfections much easier.

Chas H · #8 06-07-2009, 09:55 PM

Talk to your local concrete mixers. There are smooth flowing, self-leveling mixes for radiant heat floors that may be applicable for your case. And be very careful about removing a basement floor as it likely stabilizes the foundation; in fact the floor may well be part of the foundation.

t walgamuth · #9 06-07-2009, 10:06 PM

If that floor stabilizes the foundation heaven help that foundation.

If you can explain how to pour a foundation and floor together I would appreciate it.

Hatterasguy · #10 06-07-2009, 10:12 PM

Quote:

Originally Posted by mpolli

I wonder how much to grind it smooth? That's a pretty big area. You might get a quote on busting it out and repouring. I don't think I'd want to do that myself.

Probably to thin, those old slabs are often skim coats. Concrete is heavy when doing it by hand. So the old guys often cheated, at least from what I have seen.

Can you get a cement truck close enough to pour it? Can they get the shoot in? Mixing that much concrete is for the birds, buy it by the yard off a truck. Its not that much.

Just remember the trucks weigh 80k pounds, so they will do some damage to your driveway, like break it into ruts...

Its a horrible job, so I would pay someone to break it up and shovel it out. Than load it into the dumptruck with the backhoe myself. I wouldn't dig out much, since you could undermine the footings. Just lay down some plastic and rebar and pour a new 4in slab. Pouring concrete sucks, I'd have our concrete guys do it.

jt20 · #11 06-07-2009, 10:12 PM

right. The most it could be is a footing for the walls. Who knows what they did 95 yrs ago.. but that is not common practice these days. It would crack in no time.

Chas H · #12 06-07-2009, 10:12 PM

Quote:

Originally Posted by t walgamuth

If that floor stabilizes the foundation heaven help that foundation.

If you can explain how to pour a foundation and floor together I would appreciate it.

The house is 95 years old for starters. Who knows how it was constucted.
Have you never heard of a raft foundation. You can do the search.

Hatterasguy · #13 06-07-2009, 10:15 PM

Quote:

Originally Posted by Chas H

Talk to your local concrete mixers. There are smooth flowing, self-leveling mixes for radiant heat floors that may be applicable for your case. And be very careful about removing a basement floor as it likely stabilizes the foundation; in fact the floor may well be part of the foundation.

Not on most homes. The footings are what holds the walls in place. The floor is just a 4in slab poured over the lip of the footings, just to finish it so your not walking on dirt.

Most older homes had dirt floors, and they poured a concrete floor much later...sometimes 300 years later...to finish it off.

BTW I doubt his concrete floor is 95 years old. Usualy 1930ish is when you start seeing poured concrete in homes. Until than it was all mason work. Or if it was a cheap house, wood poles and a crawl space.

Chas H · #14 06-07-2009, 10:21 PM

Quote:

Originally Posted by Hatterasguy

Not on most homes. The footings are what holds the walls in place. The floor is just a 4in slab poured over the lip of the footings, just to finish it so your not walking on dirt.

Most older homes had dirt floors, and they poured a concrete floor much later...sometimes 300 years later...to finish it off.

When building a new house you pour in the following order...footings, walls, floor.

BTW I doubt his concrete floor is 95 years old. Usualy 1930ish is when you start seeing poured concrete in homes. Until than it was all mason work.

The weight of the house and the first floor diaphram hold the walls in place.
I live in area where many houses and in some cases entire villages are 100+ years old. I posted my caution about removing the basement floor based on local experience.

MS Fowler · #15 06-07-2009, 10:24 PM

Why not place a wooden floor, ( 5/8" OSB) over a 6 mil poly vapor barrier right over the concrete? You could use 2X4 as joists to let you shil it level if you want. Leave the concrete like it is.