I have a hidden room in my house that I would like to turn into a closet. The room (currently only accessible from the outside through the vent) vents the utility room to the outside. I'm not sure why it was designed this way, other than maybe because it was easy since it was already framed for a door. Since I'm going to turn it into a closet I need to change the location of the vent. There's plenty of room between the vent and the utility room to change the location. My problem is that the outside wall is cinder block. What tool would be recommended or is best to use to cut or hammer through cinder block?

2 Answers 2


Since concrete blocks are fairly thick, I'd drill several holes along the line you want to cut with a masonry bit, then use a use a mini jack hammer such as a small DeWalt with a 1/2" chisel bit. The hole will not be perfect shape etc, so you will need to fill around the vent after installed with some mortar. The pilot holes will help keep the hole in a rough shape and avoid breaking off large pieces of the block. Even it some block breaks, you can fix it up after with the mortar mix.

  • They're not cheap, but watching it used on the Holmes window well episode, that thing was cutting through everything like butter. I think this is the DeWalt version: amazon.com/DEWALT-D25899K-SDS-Demo-Hammer/dp/B0014GEY8I
    – BMitch
    Aug 3, 2011 at 12:59
  • Definitely not cheap, but I imagine I may be able to rent one. Thank you, I appreciate the answer, I'll look into it more.
    – Evan
    Aug 3, 2011 at 13:52
  • There is a gas powered block cutting saw that you could use, but it has a 10'' blade so cutting the sides of your vent hole would not be pretty. I would do a shirlock homes suggested just be careful either way.
    – lazoDev
    Aug 3, 2011 at 15:54
  • Thanks lazo, I think I'm going to go the route of the mini jack hammer. I know someone that has one, so that will save me quite a bit of money.
    – Evan
    Aug 4, 2011 at 13:44

A diamond concrete saw blade.

To do it right, you're going to need a specialized saw, possibly with water cooling. Otherwise the blade just melts. These blades are not cheap, so you need to protect them with a first-class water cooling system (A garden hose with a Skilsaw will not work, as you will have the additional risk of electrocution).

If you do use a dry saw you're going to need a respirator (you don't want to be inhaling that silica dust).

  • This was my first guess, but the more I thought about it I wondered if I was going to be able to do this myself. It will be interesting to see what I come up with. Thanks for the post.
    – Evan
    Aug 3, 2011 at 13:53

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