Hey there, time traveller!
This article was published 7/9/2003 (4620 days ago), so information in it may no longer be current.
My house was built in 1918. My foundation is constructed of limestone (rock size pieces) cemented together and of course it leaks in numerous places. In many spots the cement has fallen out of the cracks and I expect a basement such as this is constantly moving and shifting, somewhat.
I have been told new weeping tile and tar over the outside basement wall will solve the problem. Because of the nature of the basement wall I have trouble believing it is possible to fix this type of basement and make it leak proof.
What is your opinion? What would you recommend to help solve or at least improve the problem?
--Terry Schultz, Winnipeg
Answer: There are a number of things you can do to help minimize seepage into your stone foundation before attempting excavation, but they may not fully solve this common problem. It is expected that older stone foundations will leak as some point in time. This is due to the deterioration of the mortar between the individual stones. When the cement in the mortar wears away, what is left is sand, which comes loose and allows moisture to seep through the spaces between the stones.
The original purpose of a basement in a home of this age was simply a place to hold the mechanical systems within the home, such as furnace, plumbing pipes, and electrical wiring and to minimize movement due to frost heaving. It was never designed to be a living space. With changes in our lifestyles, many people have adapted their basement to accommodate a rec-room, bedroom, laundry room, or other living space. This presents a problem when water leaks through the foundation walls in the spring or after heavy rains. A damp basement is not a good environment for humans as mould, rot and other health and safety concerns may arise. This is not to say that a foundation and basement, even an older stone one, cannot be relatively dry.
There are several relatively easy maintenance tasks that can be done before attempting costly foundation repairs. The first item is to inspect the roof and eavestroughs on the home to ensure they are in good condition and not leaking or damaged. The downspouts should be directed away from the foundation for several feet to prevent localized dumping of water near the foundation. The soil and grading around the home should be raised to provide a slope away for the initial 3 to 5 feet. Finally, vegetation and trees should be trimmed back from the home to allow fast drying after rain.
Many of the problems with basement seepage are due to deterioration in these areas, and getting rainwater and snow runoff as far away from the foundation, as quickly as possible may make a large improvement in basement dryness. This may not, however solve the seepage problem if the foundation mortar has been poorly maintained and falling out. The foundation above grade on the exterior should be patched and the inside of the foundation as well. All loose material should be scraped out of the joints between the stones and then re-pointed with new mortar. A complete parging coat over the entire inside of the foundation after re-pointing may also help prevent seepage and will make it easy to identify new cracks and mortar wear.
Digging down on the exterior of the foundation, replacing or installing weeping tiles and damp-proofing the foundation should eliminate seepage. Proper damp-proofing with conventional bitumen based coatings, or tar as you have described it, is difficult due to the uneven surface of the stones. A better solution may be a foundation membrane designed specifically for foundation damp-proofing. There are several designs and manufacturers of such systems, and most are moderately priced and quite effective. These must be properly installed, after the foundation has been patched and prepared according to the manufacturers instructions, to work.
New plastic weeping tile should be installed on the exterior, along with the new membrane, and modifications may be required inside the home, as well. Many older homes with stone foundations had no weeping tile installed, or the older tile has become blocked or damaged due to movement in the concrete basement floor slab. Often, sections of this concrete slab will have to be cut out to accommodate new weeping tile installation on the inside of the basement. This new plastic piping will be connected on the exterior of the home to the new outside weeping tile and to the floor drain catch basin or a sump pit on the inside.
These repairs are very costly, but can be very effective in stopping moisture intrusion into the basement, if done properly. Careful consideration should be given to the cost and value before committing to such a large repair. Trying my earlier suggestions for ways to get the water away from the foundation and normal maintenance may provide adequate leakage protection for a much more reasonable amount of money.
Ari Marantz is owner/inspector of Trained Eye Home Inspection Ltd. and is the P. R. Rep. for the Canadian Association of Home & Property Inspectors- Manitoba (www.cahi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P. O. Box 69021, #110-2025 Corydon Ave., Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358.