Uneven Basement Floors

Most good contractors and crews are busy unless a big recession hits. Sometimes mistakes are made that go unnoticed by both inspectors and the homeowners. These could include not finishing up a closet or failing to adjust a door, small stuff in most cases. However, there are some miscalculations that creep up on the homeowner later on. And one of these is an uneven cement basement floor.

A basement floor that has imperfections is not the end of the world but it is annoying and leads to higher costs when it comes to framing and finishing. A good carpenter can make cuts to allow for the bumps and hollows on the floor and ridges can be ground away. But what about flooring?

If the basement is used mainly as a storage area a slope or hollow won’t really have an effect on the area. However, it’s when flooring is put in that the real test begins. If the subfloor is to be framed then the studs can be shimmed. A leveled line suspended over the area will show where the frame has to go to be leveled. Once the subfloor is down the finished flooring or tile can go right over without fear of sloughing or cracking.

If the cement floor itself is the subfloor then leveling the floor must be done with a leveling compound. This is a cementitious mixture which is mixed wet so that it will find the hollows or slowly build the floor up the high spots. The leveler is mixed in a cement mixer and poured on to the floor where it finds all the low places. Then with a gage rake or leveling squeegee the slurry is distributed. It dries in 15 minutes but needs 24 hours to harden. Any high spots that are left can be chipped away or ground down.

Now you are ready for your subfloor.

Cracked Cement Floors

The basement floor, or home pad, is usually the last cement work performed on the home – after the footings and foundations. In some cases the contractors are trying to make up time and do not compact the floor area enough. This produces cracks in the floor as the house settles.

By its very nature concrete contracts about 1/16″ for every ten feet. If the mixture is wetter (again, to save the contractor time) the shrinkage is even more. And because this shrinking process causes tension within the slab cracking is more likely to occur. This usually happens within 30 days of the pour. This is because concrete is extremely strong when compressed but only 1/10 as strong when forces are pulling it apart.

To alleviate cracking steel mesh is added to reinforce the pad. Another good way to do this is by adding plastic fibers to the cement. This is done at the cement plant and provides another way to relax the pressures.

The key is to ask your builder questions but know the answers beforehand. How? By reading up on cement and asking reputable cement companies before the pour is made. This may require going out to the plant office and asking questions. As a business they want to put their best foot forward and will give you ammunition when interviewing your builder.

If your floor is already cracked, and there is no vapor seal below the pad to prevent water or radon gas from seeping in, you can do this yourself. Rent a diamond circular saw and saw along the crack, making a nice groove. You can buy a thin foam rope which you can press into the crack. After this is done apply a polyurethane sealant and smooth over.