Advice to replace cinder blocks in wall

Old 04-20-05, 06:27 AM
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Advice to replace cinder blocks in wall

My intention was to post this in this forum but yesterday I accidentally posted it in another forum. I am reposting it here because this forum fits the best.

My house is in Florida and there is a wall air conditioner unit in a bedroom that I want to remove. The wall is a cement block wall. Before I start, I would like to know what I need to do and any problems that I could encounter.

This is my plan:
Remove the a/c unit.
Knock out any cement blocks that were partially cut when the a/c was installed. I think this is needed in order to have the new blocks staggered with the old blocks for strength.
Use cement to place the new blocks into the wall.

There are some questions that I have:
What tools should I use to knock out the partial blocks and old cement?
Should I use any rebar or any other items to make the wall stronger?
Should I fill in the blocks with cement to make them stronger?
What type of cement should I use?
Any other hints, suggestions or cautions that you may have?

Old 04-20-05, 04:57 PM
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Just replace the blocks that were removed, make sure the hole is square and fit in the blocks, use type S motar, the other blocks are probaly not filled solid a small hole for an AC does not hurt the integerty of the wall, triyng to cut out the other blocks will cause more damage
Old 04-20-05, 05:47 PM
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The only thing I might add to Frank99's reply, is to purchase a tuck pointing tool (long and narrow) so that you can really tuck the mortar inbetween the blocks so that it's got some strength. No rebar or solid pouring is needed- just a well packed joint. Don't mix the mortar too thin or it will be weak- a stiff putty consistancy is just right. Wet the blocks so that they don't suck up all the moisture right away. If you have trouble getting the top block in, dry fit it using some wood shims as spacers- then tuck point around it and pull the shims out when you have the block packed in there good and solid and repair the holes the shims left.

Strike the mortar joints smooth with a curved joint tool once it has begun to set up- this will smooth the cement and make the joints stronger as well.

If you do need to knock out some blocks- (if they were indeed "cut" they may have been cut in a bad spot as far as your layout is concerned) you just need a small 5 lb hammer and perhaps a wide cold chisel to remove all the old mortar. Remove the cement block, then work on the mortar. Tap lightly- you don't want to crack any of the good blocks.

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