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Robert Lamoureux: Water seepage through walls can be hard to fix

Your Home Improvements

Posted: January 1, 2010 10:01 p.m.
Updated: January 2, 2010 4:55 a.m.
Hi Robert,
We have water seeping through our subterranean garage wall along approximately 120 feet.  Pieces of concrete are starting to come off in some places, which is the cause of great concern for us. We have spoken to three contractors about how to repair and they each have a different opinion. They are suggesting either Xypex, Dry Lock or a coring injection. We would very much appreciate sharing your views on this matter as we feel it is now an emergency.  Thank you very much.
Charles R.

Hi Charles,
The injection system is where you would stand inside your garage, core holes in the wall and inject a waterproofing agent through to the other side of the wall.  This material would then spread between the dirt and exterior face of the wall to create a waterproof coating.  Based on my experience though, the injection system does not work that well. There always seems to be a problem.  

Xypex is a material that is applied to the inside of the wall, which we call negative waterproofing. First you would chip and groove out any visible cracks and patch with hydraulic cement. After those repairs have cured, you clean and wet so the chemical can penetrate the surface more easily. If the wall has a smooth finish, you will need to etch or rough it to provide a good bonding surface.    

On a wall that size, you could use a push broom for the application. You want an even coat at approximately 1/16 inch thick. The second coat goes on before it cures, while it is still green.     

Xypex suggests applying water to the new surface three or four times a day for two or three days to cure properly, which is important
for the growth of crystalline formation.

Drylok comes available is different colors and is available in both a latex and an oil-base. You basically just paint it on the inside of the garage wall, so it is also negative waterproofing. According to Drylok, once applied, their product will withstand 10 pounds of hydrostatic pressure which is greater than a wall of water 22 feet high.  

For the application, you would first sandblast the wall to make sure it was perfectly clean, hose it off and let dry for 48 hours.  Then apply two coats of Drylok.  

If you were only considering the options you mentioned, I would choose Drylok, but negative waterproofing is not the “correct” or best repair because it still permits the water to come in through the back side and permeate the block. It may prevent water from seeping out into your garage, but it keeps the block saturated and, in time, the concrete will spall and the internal steel will rot.  

The right way to do this is to apply a positive waterproofing system. This would require you to excavate and expose the length of the exterior garage wall.  When you waterproof from the outside, you are preventing any water from getting into the block and seeping through.  

I would contact some larger construction companies and ask them for a bid.    Excavating 120 feet of wall for positive waterproofing is going to be expensive, but consider your long term options.

Hi Robert,

I have a patio made from brick pavers. I swept sand in between the bricks to keep them stationary, so they don’t move from side to side, but they sink. Every couple of years I pull up one corner, spread some dirt, and then put the bricks back. Is there a way to not have this problem?
Victor G.

Hi Victor,
It’s a compaction problem. It’s settling and you’ll probably never get away from that, unless you put in a concrete base or pad. 

Then you can either set your pavers in a sand bed or in mortar.  

Keep in mind that if you use mortar and your concrete cracks, it will transfer up and cause your pavers to crack also. If you stay with a sand bed, the cracks will not transfer through.   

The same is true when you are setting tile. You always put a slip sheet down.  This way, the tile won’t crack when the concrete slab does.  

Hello Mr. Lamoureux,
I’ve got a question about space heaters. I always hear that they are responsible for many fires every year, but how? All the ones that I have will automatically turn off if they tip over. I like using them and see them as being very safe. Thank you.
Alex W.

Hi Alex,
Space heaters are among the most common causes of house fires. There are precautions you should take and dangers you should be aware of before using them. 

Here are some safety tips as recommended by the U.S. Consumer Product Safety Commission:
Only use heaters that have been tested and certified by an OSHA recognized testing laboratory like Underwriters or Wyle.  
Make sure that your heater has a protective guard around the flame or heating element.   
Children or animals should not be left alone in a room with a space heater.
Like the labels say, keep the heater at least three feet away from everything.  
Don’t place the heater under something that may drop on it from above, like a towel.
Always turn the heater off before going to sleep.   Many fires are started each year by a pillowcase or sheet coming in contact with the heating element while sleeping.   
Never place anything directly on the heater. Some people will dry clothes or shoes on them.  

Specifically for electric space heaters:
As you mentioned, use only newer heaters that have the automatic shutoff switch.
Don’t use electric heaters in the bathroom or wet areas due to possibility of electric shock.
Never run the cords under rugs or carpeting. This can cause the cord to overheat.  
It’s always best to plug a heater directly into the receptacle. Only use an extension cord, a heavy duty # 14 or # 12 AWG, when absolutely necessary.  

For Gas or Kerosene heaters:
Always buy the proper size heater for the room.  The wrong sized heater might produce too many pollutants.
If you use an unvented fuel burning heater, keep the doors to your home open to help vent the pollutants.
Do not place gas or kerosene heaters on rugs or carpets and only use 1-K grade kerosene in a kerosene heater.

Robert Lamoureux has 25 years of experience as a general contractor, with separate licenses in electrical and plumbing contracting.
He owns IMS Construction Inc. in Valencia. His opinions are his own, and not necessarily those of The Signal.
Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor, after that contractor has made a thorough visual inspection. Send your questions to


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