another basement waterproofing question?


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Old 08-30-07, 11:39 AM
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another basement waterproofing question?

i dug the trench and have laid all the pipe and gravel for the internal drain. now im drilling weap holes into the block. my question is how far apart do the holes need to be? thanks
 
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Old 08-30-07, 05:14 PM
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The holes should go into each of the voids in the blocks. That way if any water gets in there it will be able to drain.
 
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Old 08-31-07, 06:57 AM
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so you are saying to drill a drain hole in each block all the way around? cause some i have spoke to say only every 3-10 feet apart.
 
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Old 08-31-07, 09:25 AM
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another basement waterproofing question?

The spacing can depend on how the block were laid.

If you have vertical reinforcement in the wall, you must have tubing between the rebars.

For the common unreinforced basements, some contractors will lay the block in a full mortar bed where there is mortar under 100% of the faces shells and webs of the block.

Other contractors will only put mortar under the face shells, leaving a longitudinal opening on the center of the footing so any moisture can flow to any exit or drain. In fact, some contractors will use a special block that has the holes for the tubing.

Knock out a face shell or two on some of the block on the footing to see if there are mortar barriers at the cross webs. If there are none, you can space the tubing to every 2 or 3 block or so.

You should not have to drill all the holes. Often, you can use a heavy rebar and drive it in where the block and footing meet. The block face shell should be about 1 1/4" to 1 1/2" depending on the block manufacturer. I have even seen some people use a hose to flush out any debris in the cores and make sure the system drains before covering.

After you have the holes, insert your tubing about 1 1/2 to 2" and use mortar to close the hole and hold the tubing in place until you pour the concrete on the footing that patches/levels the floor.

Just a note - It is always good to keep some braces between the wall and the slab to prevent the wall from sliding in the case of unexpected rains.

Dick
 
 

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