Flushing can help old weeping tiles perform their job

Hey there, time traveller!
This article was published 17/07/2005 (7418 days ago), so information in it may no longer be current.

QUESTION — I have to have the weeping tile replaced on two sides of my house and the foundation wall waterproofed. At this time I can only afford to have two walls done. Is it possible to clean out the tile on the other two walls while the corners are exposed without digging along all the foundation walls? This would be a temporary measure until I can afford to have the other two walls done.

Is there a product that could be inserted into the existing weeping tile that was cleaned at this time to control future clogging of the existing tile?

–Barry Blair, e-mail

ANSWER — This is a very timely question, as many homeowners are finding that the recent heavy rains and saturated soil conditions are causing basement leakage. Many foundation contractors are inundated with work due to these unusual conditions for this time of year. I will attempt to answer your question while giving an explanation of what repairs you may need to undergo.

Most homeowners in southern Manitoba have heard about weeping tiles but most are not familiar with their form or function. The style and operation of the weeping tile is largely a function of the age of the home. Older homes may have concrete or clay weeping tile that is much more subject to blockage or damage than modern plastic drainage-tile systems. The older weeping tiles are simply round cylindrical tubes that are placed near the footing at the base of the foundation, after a foundation is poured. These tubes are placed end to end around the entire foundation and are connected to similar tubes that run beneath the concrete basement floor slab. The individual tiles will have small gaps between them and the adjoining units, which will allow excess soil moisture to seep into the tile system. This water will flow, by gravity, to the termination of these crude pipes, inside the catchbasin and floor drain in the basement.

This older system may work well for many years, but often will fail due to blockage of the tubes with clay soil due to shifting or physical damage. Modern plastic weeping tile is corrugated, continuous pipe and is not subject to crushing, like older ones. Because these plastic pipes are continuous on the exterior of the home, they are much less likely to plug with soil. The outside drainage tile is perforated to allow water to enter and is attached to non-perforated pipes below the basement floor slab.

When you have your foundation excavated and damp-proofed, an integral part of the repair is to replace the older weeping tile on the exterior with new plastic lines. This will ensure proper drainage that may have been lost with the older system. If you are repairing only two of four walls, you may be limiting the effectiveness of the system. This will depend, however, on the function of the other older weeping tile on the remaining two walls. If they are not damaged, it may be possible to clean or flush them out and roughly connect them to the new system. This will depend largely on the condition of the older tile below the floor slab and whether this will be replaced along with the exterior tile. This clearing should only be done by flushing with water, although other methods are sometimes used. A Roto-rooter system is sometimes used to clean out plugged tiles, but can damage the older tile. The old tile may be brittle and the cutting knife on the rooter can break weak tiles, allowing them to collapse and become useless.

If the tile below the floor slab does not drain properly when attached to the new plastic tile on the exterior, they are likely damaged or crushed. To function properly, sections of the concrete basement floor slab will have to be cut and the old damaged tiles replaced with new plastic. It may be possible to do this with the entire internal tile regardless of whether it is being replaced outside. Once installed, it may be possible to partially clear the old exterior tiles by flushing them with water through the new exterior and interior tile. Again, this is completely dependent on the integrity of the old tiles outside the foundation walls. If they are crushed or damaged, there is no hope that they will function without replacement.

In that situation, replacing only half of the system will improve drainage considerably, but may not be a complete solution. Excavation and upgrading to the weeping tile on these other walls will likely be required in the future. It may not be as critical depending on grading and drainage of the lot in relation to location of the other walls. If seepage is noticeable only on two walls at this time, I suggest doing the repairs on these to start. Future repairs are likely, but are not essential if no water is seen in these areas or no visible cracks are seen.

Foundation, damp-proofing and weeping-tile repairs are ideal if the entire job is possible, but can be done at varying times. Even a partial repair may improve the situation considerably, often eliminating troublesome seepage.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of 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.

trainedeye@iname.com