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-   -   Door opening in load bearing block wall (http://www.diychatroom.com/f19/door-opening-load-bearing-block-wall-80470/)

SS396 09-03-2010 06:05 PM

Door opening in load bearing block wall
 
Hello, i am working on an old house with a clay block perimiter foundation, there is also a load bearing clay block wall that runs through the center with a 40 inch door cutout in about the center. This cutout for a door is precisely under a load bearing wall on the first floor. (that holds up the floor joists for the second floor). There was no beam or lentil previously installed. The only thing holding up the two top courses of block was a 2x10 laid flat across the top of the door opening resting on about 2 inches of block on either end. Naturally, the 2x10 is now sagging in the middle and the joist that sits on the whole mess is down about 2 inches.
I am planning to jack the joists in the area, remove eight feet of block and replace the block with 2 ea 4x8x 8 ft lintels. The joists above will sit directly on the lintel. This will also raise the top of the door opening which is needed to install a standard door. My question is whether this is an appropriate use of the lentil or should i be using some other kind of beam?
Thanks so much

Daniel Holzman 09-03-2010 07:18 PM

I am having a hard time exactly understanding what you are planning to do, perhaps a scaled diagram or a photo would help. I think you are planning to replace clay block with a header (the term lintel is usually used to describe an iron or steel element placed above a window in a brick or block building). I am unclear what you are planning to use to support the header. I also cannot tell from the description how much load the paired 4x8 x 8 foot long header is required to carry.

Design of a header generally requires sizing the header for the live and dead load it will carry, plus designing adequate supports to carry the load down to the foundation, and designing appropriate connectors to resist unusual loads such as seismic, wind or impact. The design always requires careful evaluation of the maximum total load the header can be subjected to over the life of the structure.

jomama45 09-03-2010 09:38 PM

Quote:

Originally Posted by SS396 (Post 495586)
I am planning to jack the joists in the area, remove eight feet of block and replace the block with 2 ea 4x8x 8 ft lintels. The joists above will sit directly on the lintel. This will also raise the top of the door opening which is needed to install a standard door. My question is whether this is an appropriate use of the lentil or should i be using some other kind of beam?
Thanks so much


This is exactly what a re-enforced, precast concrete lintel is designed to do. If a 2x10 on flat held up to any degree, there's no question that the lintel will work just fine.

jomama45 09-03-2010 10:17 PM

Quote:

Originally Posted by Daniel Holzman (Post 495609)
I am having a hard time exactly understanding what you are planning to do, perhaps a scaled diagram or a photo would help. I think you are planning to replace clay block with a header (the term lintel is usually used to describe an iron or steel element placed above a window in a brick or block building). I am unclear what you are planning to use to support the header. I also cannot tell from the description how much load the paired 4x8 x 8 foot long header is required to carry.

Design of a header generally requires sizing the header for the live and dead load it will carry, plus designing adequate supports to carry the load down to the foundation, and designing appropriate connectors to resist unusual loads such as seismic, wind or impact. The design always requires careful evaluation of the maximum total load the header can be subjected to over the life of the structure.


Here Dan, check out page 50 for information on concrete lintels:
http://www.bendindustries.com/litera...%20Catalog.pdf

stuart45 09-04-2010 11:42 AM

Hi Joe,
Do you ever use metal box lintels? Much easier to handle and can take greater point loads when other load bearing masonry walls are on top of it.
http://www.condell-ltd.com/Page.aspx?catid=277

jomama45 09-04-2010 04:46 PM

Hey Stu,

I've never seen anything like that before, only heavy steel I-beams with a wider plate to welded to the bottom to carry block. Seems like an interesting idea, as they come standard up to 15' long. (Assuming my math is right) Any idea what they weigh per foot?

stuart45 09-04-2010 05:07 PM

Not sure what they weigh per foot Joe, but they are much lighter than a concrete lintel. Will find out for you. Two guys could lift in the big ones. They also will take heavier point loads than concrete. Catnic lintels have been around since the 70's in different forms. The engineer who invented them named them after his kids, Katherine and Nicholas(cat and nic). There are even some now that will carry the two skins of masonry for a cavity wall over a bay window.
Just looked up the weight, the CN99 is 19.5 kilograms per metre, which is probably about 12 lbs per foot at a rough guess.

SS396 09-05-2010 10:38 AM

additionla info
 
if you can visualize a 30 x 30 ft foundation with a block wall running right down the center that splits the basement into two halves. the center wall has a 40 inch door opening located at about it's center. the floor joists above run perpindicular to the center wall and rest immediately on the wall. it so happens that there is a load bearing wall located on the first floor that sits on the floor joist immediately above the door cutout. i need to install a "header" across the door cutout. i selected an 8 ft concrete lintel because i dont trust the clay block and or i wanted to give it some additional bearing surface on either side of the door cutout. the lintel will be used as the header for the door cutout. there is no room for additional block courses above the lintel. the joist with the biggest load sits immediately on the lintel and perpindicular to it, and the load will be applied over the center of the door cutout. since there are no block courses over the lintel, i guess this would be considered a point load? i hope this further explains the point of my original question. thanks

stuart45 09-05-2010 01:47 PM

Quote:

Originally Posted by SS396 (Post 496203)
since there are no block courses over the lintel, i guess this would be considered a point load? i hope this further explains the point of my original question. thanks

That is a point load. Make sure the lintels will take the load. You could use a shorter lintel with concrete padstones underneath to spread the load onto the clay blockwork.

SS396 09-05-2010 06:07 PM

ok i think you are helping me refine the question. will the concrete lintel accept a point load in the center of the unsupported 40 inch span and how could i know what tha load will actually be? should i use something other than a concrete lintel for the situation i have described?

stuart45 09-05-2010 06:35 PM

Whether the lintel will take the load depends on how much of a load it is taking. You would have to calculate the load, or get an SE to look at it.

SS396 09-13-2010 03:23 PM

Hello, i called the company that manufactures the concrete lintel and i was told that since ther are no courses of block above the lintel that i could not use the lintel for this application. (he said no load could be applied within the apex area above the lintel defined by a 60 deg triangle area above the lintel.) so then, what is state of the art for installing a header above the doorway opening to support the load bearing wall above. I guess if this were just a carpentry framing question it would be to sandwich a couple of 2x10s or lvl lumber to make the header. Is this what i should use or a steel i beam header, or what? What would be used in a new house if a load bearing wall rested on the header of the door opening of a block wall? Thanks again for your help

stuart45 09-13-2010 05:27 PM

Quote:

Originally Posted by SS396 (Post 500493)
What would be used in a new house if a load bearing wall rested on the header of the door opening of a block wall? Thanks again for your help

Here we would use a steel box lintel, or an RSJ(rolled steel joist), depending on the load it was taking.


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