Excess moisture from cellar’s dirt floor can cause trouble

Q. My son lives in an old house that has a dirt floor cellar that gets damp in the spring. I was wondering what could be done about covering the floor with plastic, or maybe you have another idea. He runs a dehumidifier down there and it helps some. Any ideas would be appreciated.

A. Old, drafty houses benefited from some moisture emanating from their cellar’s dirt floor, as long as the cellar was not soaking wet. But excess moisture, particularly if the living areas have been tightened up, can result in serious problems, both in the cellar itself — rotting timbers, etc. — and upstairs.

In most cases, it is best to cover a dirt cellar and crawl space floor with plastic. The soil should be smoothed out, if need be, and any sharp objects removed. If the cellar is not used, a single layer of 6-mil plastic is often sufficient, but if the cellar is used for storage, laundry, workshop, etc., it is preferable to lay a couple layers of plastic, unless you can find heavy agricultural plastic in stores such as Agway. I got some years ago from a farmer who had to replace the plastic on his greenhouse.

You can often find used plastic on construction sites; contractors are glad to give it away to spare them having to pay to dump it. Cover the used plastic with a new, clean layer.

Walking boards can also be placed over the plastic where traffic will be heavy, or you could make sure that everyone who will be walking on it wears sneakers or similar shoes.

If there is leakage through the old stone walls, and grade corrections do not solve the problem, a small trench should be dug at the base of the walls and the dirt used to form a small berm on the inside edge of the trench. Lay the plastic only to the top of the berm in order to let any water leaking through the walls to percolate in the trench and not flow over the plastic. This applies to crawl spaces as well.

Once this is done correctly, your son may no longer need to use a dehumidifier.

Q. Our 10-year-old, two-car garage (21 square feet) faces the street, and I would like to dress up the concrete floor, which is in good shape. I have two questions:

Ÿ Salt from the winter roads have created white spots on the concrete near the floor drain. My guess is the salt has been absorbed into the concrete. I have cleaned this with standard cleaning products, but every time it gets wet the white spots come back. What can I do to remove the white spots and maybe seal the concrete?

Ÿ After I eliminate the white spots, I would like to apply an epoxy coating like UCoat It or the new garage floor tiles like Race Deck or Swisstrax.

I have read that the epoxy can peel due to moisture in the concrete. The garage floor tiles have the open weave pattern that allows moisture to flow under the tile to the drain. Do you have any experience with either epoxy or garage tiles? I am more concerned with durability and looks rather than cost at this time.

A. The white spots are efflorescence — salts left after the water carrying them has dried up. This is the same chemistry as salt flats; seawater is captured in pools and when the water evaporates, the salt can be collected.

You should be able to remove the efflorescence using a stiff dry brush, but if this is not sufficient, do so by wetting the brush.

Any paint, including epoxy, is subject to peeling if there is moisture under it.

I have no personal experience with UCoat It, Race Deck or Swisstrax. Some problems have been reported with UCoat It: peeling where car tires sit, etc. It may be due to inadequate preparation of the surface or not enough curing time before the car is parked on it.

Race Deck and Swisstrax are interesting products, and seem as if they may hold up better.

But don’t take my word for it. These floors are expensive, and it seems to me that you are taking a financial risk. Just keeping a plain slab clean is not that difficult, but it’s a personal choice.

Q. I have a question for you that I cannot figure out. This past weekend I got a frantic call from my wife who was in our lower level. My daughter was washing a load of laundry, and when the washing machine hit the rinse cycle, the utility sink — located right next to the washer — and the bathroom sink started to fill with water.

The water exit hose leaving the washer dumps into a PVC pipe with a Y connection at the inlet for the tub, and there is a vent pipe attached to the other leg of the Y. They then connect with the P-trap, which then goes horizontally through the wall and connects to the utility tub (which also has a P-trap on it) and I am assuming connects through a T connection to the sink P-trap as well.

I am not sure why this would all of a sudden occur as it has never happened in the two years we have been here. I checked the end of the initial Y that has the open end vent on it and it is clear. Could there be a clog somewhere else? The water does go down once the drain cycle is finished.

A. It does sound as if there is some obstruction in the waste line between the utility tub and the bathroom sink. The fact that the water eventually drains suggests that the obstruction is enough to cause the surge of the washer’s water to back up.

It looks like something washed down the drain and got stuck there. If you can run a snake through, it may dislodge whatever is causing the backup, but if you can’t, you may have to call a licensed plumber.

Q. I enjoy reading your column in the Daily Herald every Sunday. Looking to install hardwood floors on a slab, I have gotten different opinions on what type of underlayment to install. I do have a height problem because of French doors — also what do you think about engineered wood on a slab? I do not want laminate flooring.

A. The most important things to consider are moisture migration from the soil below the slab and how flat the slab is.

You didn’t say whether the slab is above grade, on grade or below grade — this is important to know. Since you mention French doors, I will assume that your house is built on a slab on grade.

First, using a 10-foot straight edge, check to make sure the slab is absolutely flat. In case there are some depressions, they need to be filled with a leveling compound. High spots should be ground down.

Next, you need to check the moisture content of the concrete by taping down all four sides of some 2-foot square pieces of 6-mil clear plastic with moisture-proof tape. Place several pieces of plastic on the slab, as the moisture content may vary widely from place to place. If there are no beads of water under any of the plastic after two days, it is safe to consider laying a wood floor, even below grade.

Apply a sheet of 6-mil plastic over the entire slab as an essential vapor retarder.

Since clearance at the French doors is limited, you will probably not be able to lay plywood underlayment power-shot into the slab. So look into Elastilon underlayment, www.elastilon.com, over which engineered flooring can be applied. Follow the directions carefully to obtain a floating floor.

Interesting follow-up on water heaters: “I read with great interest your answer regarding the 25-year old water heater.

“I just replaced our original water heater after 20 years. The initial reason was due to the water system changing, where the house now occasionally sees water pressure changes from the town water supply such that what equates to a water capacitor (a small tank on the inlet with about a cubic foot of air) is now required. I learned about this after seeing that the emergency pressure relief valve had released a few times per week, putting water on my floor.

“Vermont Gas informed us of that, and also pointed out that while my heater could very well be OK, given its age, it could start leaking — and particularly due to the heater’s age, the leak could progress rather rapidly.

“Since we needed to have the ‘water capacitor’ (my terminology) installed anyway, it made sense to replace the whole tank. Looking at the capital cost of a water heater being around $2 per week, it would be silly to risk a flood and an urgent replacement to save that kind of money.

“One story, which does make sense, that VT Gas told me when I was asking about warranty: When you are looking at the better models, the difference between the longest warranty vs. the second longest is probably just the model number of the water heater — i.e. the actual heater is exactly the same. The extra cost is really just an extension of the ‘insurance’ (warranty length) from the supplier.”

Ÿ Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via email at henridemarne@gmavt.net.

© 2012, United Feature Syndicate Inc.