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Discussion Starter #1
Do I need one for a cinder block basement wall that's filled with concrete?

I'm installing a door. Some have told me its not nessesary wih concrete filled blocks. Not sure why.

If I need one, can I use a piece of angle iron? Does the angel iron have to be the thickness of the wall?

Thanks
 

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quik answer - only if you don't want the blocks above the door to fall down,,, yes, angle iron can be used,,, ( ooops, ' angel ' iron :laughing: ),,, if it were our home, 'd use 2 pieces - i inside & i outside :yes:

you're welcome !
 

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Discussion Starter #3
quik answer - only if you don't want the blocks above the door to fall down,,, yes, angle iron can be used,,, ( ooops, ' angel ' iron :laughing: ),,, if it were our home, 'd use 2 pieces - i inside & i outside :yes:

you're welcome !
Thanks alot. Figured that, just wasn't sure why so many others said a a lintel wasn't necessary in an application like this. Some said the the way the blocks are staggered and laid automatically carry the load away from door. Rather than straight down.
 

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Some said the the way the blocks are staggered and laid automatically carry the load away from door. Rather than straight down.
What they mean is that the bond of the blockwork tends to help it to be self-supporting over a certain height (put simply; if you cut one block out of a wall, the wall above won't collapse because there will be the 'cantilvering' effect of the two adjoining blocks wedged together above).

BUT, if you are cutting out for a door, your opening will be probably be at least two blocks wide, so you will need a lintel to support the block(s) above, otherwise they will come down.

As i.r.c. suggests, better with two angle irons (one inside and one out) or you could even try angel irons if you can find any :).

Can you use pre-cast concrete lintels? Might be a bit heavy and you might need to cut blocks because of course-heights, but there wouldn't be the rust problem you get with steel.
 

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Discussion Starter #5
What they mean is that the bond of the blockwork tends to help it to be self-supporting over a certain height (put simply; if you cut one block out of a wall, the wall above won't collapse because there will be the 'cantilvering' effect of the two adjoining blocks wedged together above).

BUT, if you are cutting out for a door, your opening will be probably be at least two blocks wide, so you will need a lintel to support the block(s) above, otherwise they will come down.

As i.r.c. suggests, better with two angle irons (one inside and one out) or you could even try angel irons if you can find any :).

Can you use pre-cast concrete lintels? Might be a bit heavy and you might need to cut blocks because of course-heights, but there wouldn't be the rust problem you get with steel.
After some inspecting, the block wall is full of concrete with vertical rebar. Does this have any bearing on not using a lintel? I bought some 3 1/4" angle iron for my lintel.
 

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Discussion Starter #7
If it's reinforced, it could well be OK, but if you've got the angle iron, wouldn't hurt to put it in, just incase.
THANKS Tony

Another question I have is the door frame lumber. The cinder blocks are 8". Would it be best to use 2x6? Also, how do I determine my rough opening?

When I look online at doors at the store, they have RO dimensions.

Such as a 30" x 80" door has an RO of 32x82. Is it typical to have an RO 2 inches larger than door? These are pre-hung doors.
 

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sometimes concrete block walls are actually a partition wall where the cells of the block are not filled with concrete. you'll have a column every so often and a lintel (also called a bond beam) that run across the top of the concrete blocks that is load bearing. The steel in the column ties into the steel in the beam such that the blocks are not carrying any of the load.

they may have meant since the cells are filled you do not need a lintel (across the top of the wall). you certainly need one for openings within the wall.

Not sure that's what they were talking about, but it's the only guess I can make ......
 

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tony,

always enjoy your sketches, who says an engineer can't have an artist hiding inside .....
 

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After some inspecting, the block wall is full of concrete with vertical rebar. Does this have any bearing on not using a lintel? I bought some 3 1/4" angle iron for my lintel.
THANKS Tony

I have no idea how you can tell that there's vertical rebar in the grout, but it won't really have much bearing on your situation anyways. Unless you can somehow verify that there's adequate horizontal rebar in the right location, in the right course, right over you new door opening, it's best to install a lintel.


Another question I have is the door frame lumber. The cinder blocks are 8". Would it be best to use 2x6? Also, how do I determine my rough opening?

When I look online at doors at the store, they have RO dimensions.

Such as a 30" x 80" door has an RO of 32x82. Is it typical to have an RO 2 inches larger than door? These are pre-hung doors.
Typically, it's easiest to fill the entire width of the block opening with lumber. Considering an 8" block wall should be 7 5/8" wide, you'd need to buy a treated 2x10 (1.5"x9.25") and rip it down to 7 5/8" wide.

RO's on prehung doors are generally 2" to 2.5" bigger than the actual door opening. MO's (masonry openings) are generally another 3" bigger than this, to allow for one treated 2x on each side. With a sawed-in masonry opening, I'd suggest at least 2.5" (5.5" for MO) bigger, as it's much harder to saw existing walls with a heavy concrete saw, thus they tend to get a little more "wavy" than if you were simply installing a few wood studs.......
 

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Discussion Starter #11
Typically, it's easiest to fill the entire width of the block opening with lumber. Considering an 8" block wall should be 7 5/8" wide, you'd need to buy a treated 2x10 (1.5"x9.25") and rip it down to 7 5/8" wide.

RO's on prehung doors are generally 2" to 2.5" bigger than the actual door opening. MO's (masonry openings) are generally another 3" bigger than this, to allow for one treated 2x on each side. With a sawed-in masonry opening, I'd suggest at least 2.5" (5.5" for MO) bigger, as it's much harder to saw existing walls with a heavy concrete saw, thus they tend to get a little more "wavy" than if you were simply installing a few wood studs.......
Good info!

I'm contracting out the work, so I would hope the cuts are pretty straight.

I wasn't thinking. If prehung doors are normally 2" bigger than the actual door, it would give me 1" in each side for shimming? Right?

Making it 5.5 makes sense. With the one treated 2x on each side that would eat up 3 inches and then give me 1.25 inches of play on each side. Am I calculating this right?
 
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