Basement access through stone foundation basement may be tricky

Q. Our tiny cottage has a stone foundation with a trapdoor in the living room for access to the basement. We are getting a trifle arthritic to climb the ladder monthly to change water filters and add salt to the water conditioner — not to mention the fact that we are not the favorite site at which to work for boiler maintenance.

We are wondering if it is feasible to provide bulkhead access to the basement. An old article we read advises against it because these stone foundations are not designed to withstand the excavation from a backhoe. Also, it might be inviting a water problem where there is none now because the bulkhead would need to be placed near the driveway, which is susceptible to water runoff during storms.

Is this an extremely expensive undertaking? Are we better off just setting the money aside to hire an agile youngster to see to the monthly chores?

A. Having a bulkhead built would certainly improve your situation, and it may be possible to do. So I would recommend, if you want to pursue this idea, you contact an engineer or experienced general contractor to evaluate whether or not it can be done without the risk of damaging the old stone wall in the location where the bulkhead should go. Much depends on the soundness of the stone foundation, whether it is dry-laid or mortared, how thick it is and how sound it is. Some stone foundations have suffered from soil and frost pressure over the years, but yours may not have. The soil may be excavated with a backhoe, but stay away from the foundation and do the final work by hand. The main concern is the removal of stones to frame the opening.

It is likely to be an expensive job, and the potential water problem you mention seems to be another deterrent. The money you will save by not proceeding with the construction will go a long way toward hiring someone competent to maintain the filtration system monthly. Would the firm that installed your system, or another water filtration company, have someone come monthly to take care of it?

As for the boiler’s yearly maintenance, your situation is likely not to be the only challenging one for the HVAC contractor or fuel provider who takes care of it now.

Q. Two months ago, I had my double driveway repaved with asphalt. Several days afterward, I hosed it down and washed away leaves and twigs that had fallen from a tree nearby. As I hosed the driveway, the water began to foam and washed down to the street gutter like “foam on a stein of beer,” and when the driveway dried, it looked like someone had splashed something on it. Each time after that I got the very same result, so I called the company that had done the paving. After demonstrating to them what has occurred, they could not come up with a possible cause, and left with a “promise” to do something about it. So far, I have heard nothing from them.

Do you have any idea why this is happening? The water is the same that I use to sprinkle my lawn, and there is no foam when I do that. Is it too soon after installation to get it sealed for the winter and perhaps solve the problem? Your advice is appreciated.

I look forward to your weekly column in the Daily Herald. Keep them coming.

A. Newly laid asphalt is full of oil. When you hosed it down, you stirred the oils up. It would have been better to sweep the leaves and twigs off.

It takes two to three years for the oils to dissipate, depending on the exposure to the sun, and an asphalt driveway should not be sealed until that has happened and the asphalt has turned a light gray.

It is best for you to leave it alone and let time take care of it.

Q. Several months ago, you recommended the best radon kit to test radon. I have lost that article and was hoping you could let me know which kit that would be.

Also, my basement is divided into two rooms: a game room and a laundry room. Would I have to test both rooms separately?

A. The radon testing that I recommend is the Alpha Track one. The kit is set in the lowest living area of a building and left there for several months (so two in the basement is unnecessary). The best time to set it is in the fall and leave it over the winter, when the house is closed. Testing for radon in the summer is not the best time because windows are open and people go in and out more frequently. The reading you are likely to get is close to the radon outdoors, which we cannot escape.

Charcoal testing kits are for short duration testing and can give you inaccurate readings, as the level of radon varies constantly with differences in temperature, air exchanges in the building, wind and air pressure.

Q. I live in Colchester, Vt., on the lake. My house, which is seasonal, has a chimney made of slate/fieldstone on the southwest side. I am not sure its age, but I can see that it has been repointed in places. It is 1½ stories and faces southwest from where most summer storms arrive. This spring and summer, when we had so much rain, a white, fluffy substance appeared on the hearth mortar. The hearth and surround are also stone. I’ve been told that this is a mold created by water seeping through the mortar from the outside. The chimney is capped and I do not use it at all.

I have an estimate for waterproofing, which has been recommended, although this process will not seal any cracks in the mortar. If that is the case, then I assume the problem will continue unless I have the whole chimney repointed.

Could my problem be a one-time issue caused by the abnormal rainfall? Is the waterproofing worth the expense?

A. The white substance is not a mold, but efflorescence — salts left on the surface after water, which dissolved them from the masonry, has evaporated. These salts are harmless and can easily be removed by brushing them off.

Evidently, rain penetrated the mortar joints, or more likely, the chimney cap or faulty flashing, and carried the dissolved salts deeply into the chimney all the way through to the hearth, where you found the efflorescence.

These salts are found in bricks, mortar, concrete and cinder blocks and any other manufactured masonry products, but not in natural stones.

The chimney cap and flashing where the chimney is attached to the house should be thoroughly checked by a competent mason, and any needed repairs should be made. The mortar joints should also be carefully checked and repaired. Sealing the chimney itself is not likely to be successful if the other problems are not fixed, and you may find you do not need to go to the expense after all. But the chimney cap should be sealed with a breathable siloxane-based sealer, as this may be the source of your problem.

Q. We read your weekly column in the Daily Herald, and decided to submit our problem to you, as no one we’ve talked to has been able to solve it. We have been in our home for 15 years, with an intermittent, unpredictable seepage problem.

Current problem: During certain rains, we will get seepage over the top of the foundation (the sill?). The seepage does not necessarily correlate to wind direction or amount of rain. The problem is most noticeable on the east side of the house, under the chimney, as seen in the first attached photo. The second photo gives a close-up of the top of the sill, and you can see where I’ve replaced mortar that the previous owner had applied at the top of the foundation in an attempt to keep the water out. During a seepage event, you can see little rivulets of water spaced anywhere from three to six inches apart, trickling down the wall and pooling on the floor.

You can see from the third picture that the grade line is well below the top of the foundation, so water is not pooling and overflowing the foundation during rains.

Attempts to repair: Reapplying mortar at the top of the foundation has been useless.

We have had homebuilders, structural professionals and basement seal companies inspect the problem, and no one has come up with a solution. One of the basement seal companies tried soaking the area with a garden hose, to no avail.

We have had the chimney inspected, and the inspector said the tuck-pointing is fine.

We have sealed the annulus between the outside of the chimney liner and the original chimney cap.

Other Information: Our vinyl siding is 2 to 3 years old. The siding contractor did not note any evidence of water damage under the old siding. We do not notice water coming up through the floor, or at random places in the walls. There are no observable foundation cracks.

A. From your description and the photos, my guess is that the leakage, most prominently found at the base of the chimney, is caused by water penetration where the bricks sit on its concrete base that is forming a ledge on all three sides. You can test this by flushing this ledge with your garden hose. If it proves to be the entry point, caulk the joint of the concrete base and the bricks with polyurethane caulking compound when everything is thoroughly dry.

If you cannot find polyurethane caulk/sealant locally (Home Depot carries Sikaflex Construction Sealant, which seems identical to Sikaflex-1a), you can buy it from A.H. Harris Construction Supplies, www.ahharris.com.

Water leakage at the chimney base can follow the top of the foundation for considerable distances, which accounts for the rivulets you see farther along the foundation.

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.