Making a hole in a beam?

Mauricio

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Nov 18, 2002
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I'm installing air conditioners in my living room, both above a window, a neighbor , I shouldn't perforate the beams and better install the split units lower, below the beam, which is not really practical. Any engineer that can advice if I can have a hole made in a beam to pass the tubes of an air conditioner ?

Above the window as much in the left corner as possible:

738FC852-4635-4FDC-8C37-F80044607FAF_zpsqlj6q9cm.jpg
 

ju10prd

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Typically in reinforced concrete beam design the lower half is your tension zone and the upper half is your compression zone. The induced tensions are taken by the bottom reinforcement in such a beam since steel bar works effectively in tension. Concrete is weak in tension but strong in compression and normally is working in compression in the top half of the beam.

In reference to your photograph, you most likely refer to a capping beam which should be integral with the slab above. Over the window there could be a 'drop' reinforced beam or a lintol over the window, one course of blockwork and then the capping beam.

To answer your question. A structural engineer would probably accept a small hole within a beam within the neutral zone of the beam which is that between the main tension area (the bottom reinforcement) and the main compression area (the top of the beam) which in your instance would be include the slab. Try and find where the bottom of the concrete bean is located. The bottom reinforcement would be about 2" plus bar diameter above that and any hole that an engineer may permit would be at least 2" above the bottom bar reinforcement (near middle of the beam).

That is very basic guidance. You must not damage the bottom steel reinforcement for sure. A small hole is less than 1"diameter. Every structural design has differences so if in doubt take professional advice.
 

Mauricio

Gold
Nov 18, 2002
5,607
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38
Typically in reinforced concrete beam design the lower half is your tension zone and the upper half is your compression zone. The induced tensions are taken by the bottom reinforcement in such a beam since steel bar works effectively in tension. Concrete is weak in tension but strong in compression and normally is working in compression in the top half of the beam.

In reference to your photograph, you most likely refer to a capping beam which should be integral with the slab above. Over the window there could be a 'drop' reinforced beam or a lintol over the window, one course of blockwork and then the capping beam.

To answer your question. A structural engineer would probably accept a small hole within a beam within the neutral zone of the beam which is that between the main tension area (the bottom reinforcement) and the main compression area (the top of the beam) which in your instance would be include the slab. Try and find where the bottom of the concrete bean is located. The bottom reinforcement would be about 2" plus bar diameter above that and any hole that an engineer may permit would be at least 2" above the bottom bar reinforcement (near middle of the beam).

That is very basic guidance. You must not damage the bottom steel reinforcement for sure. A small hole is less than 1"diameter. Every structural design has differences so if in doubt take professional advice.

The hole should be bigger than 1 inch, more like 5 probably to let the tubes of the air conditioner pass. I have all the drawings of my house, I think I'll try to study how the beam I would need to have perforated is actually situated. The air conditioner installer said "se hace"
 

bigbird

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May 1, 2005
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It's a split unit . The hole is just to pass the tubes.

Go for it,,,,,,,,,,

I am just a bit confused. What beam are you speaking of? I thought the walls were no more than poured concrete and rebar unless of course we are talking a "torre" where steel beams are used.
 

Mauricio

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Nov 18, 2002
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I'm completely confused myself too. Know nothing about construction. But apparently the house has beams (vigas) for the second floor to rest on the first floor. My neighbor , who's an engineer, said: you shouldn't make a hole in 'la viga' and got me scared.

Guys installing say they do it all the time...but that doesn't really mean anything I guess.
 

bigbird

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May 1, 2005
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I'm completely confused myself too. ..........


Guys installing say they do it all the time...but that doesn't really mean anything I guess.

Join the crowd. LOL

My vote goes with the installer, not that it counts.

My gut feeling the installer will not be penetrating a steel beam. Where he drills the hole will do no more than penetrate concrete.
 

Mauricio

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Nov 18, 2002
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Join the crowd. LOL

My vote goes with the installer, not that it counts.

My gut feeling the installer will not be penetrating a steel beam. Where he drills the hole will do no more than penetrate concrete.

Correct , no steal beam, just reinforced concrete beam I suppose. Anyway, I went for it as we speak and they made the hole apparently where there is no beam.

CA5C3EB2-8EBE-485C-B00A-BCE3FCACF6AC_zpsmy5skzt1.jpg
 
Last edited:

oriole100

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Oct 9, 2005
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If it is a split system you need to have 2 small holes of about 1". One for the hot and cold gas line and 1 for the condensate. If they are spaced apart it should not be a problem. Just hope you don't hit the rebar when you drill. Patch the holes when your done.
 

Derfish

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Jan 7, 2016
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Join the crowd. LOL

My vote goes with the installer, not that it counts.

My gut feeling the installer will not be penetrating a steel beam. Where he drills the hole will do no more than penetrate concrete.

I'd trust the installer, since i have been in the position of being the installer many times. Looks like he got it right. The construction I see here the blocks are laid up and then the 'voids' covered and a concrete beam with rebar inside is poured on top, so below where your hole in the picture is is thru the block and not disturbing the beam itself.
Der Fish
 

lifeisgreat

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Above every window the is minimum 4"x4" L beam that holds block above from caving down... Your A/c guy will not be drilling hole thru that I guarantee you take you two days will tools available down here. He will drill above for sure...different spans diff size 6"x4" bottom span stays same back horizontal size increase with width ..
 

Mauricio

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Nov 18, 2002
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Above every window the is minimum 4"x4" L beam that holds block above from caving down... Your A/c guy will not be drilling hole thru that I guarantee you take you two days will tools available down here. He will drill above for sure...

I had the window enlarged when I moved in 5 years ago. Whatever the guy did that made the window opening bigger I don't think he placed a beam. That's when of the guys I never ask for a job again btw.
 

Derfish

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Jan 7, 2016
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I had the window enlarged when I moved in 5 years ago. Whatever the guy did that made the window opening bigger I don't think he placed a beam. That's when of the guys I never ask for a job again btw.

n that case he probably, if he did things right slid a 1/4 steel plate across the top of the window. if not in a few more years you will start to see visible cracks in that area and then at that time a beam will have to be plate will have to be installed or something!
Der Fish
 

lifeisgreat

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If your Maestro didn't put a lentil in when he enlarged window which must overlap min. 6 inches each side he really holds a plumbers Union card!!! You will know pretty fast if you your okay first is crack as Derfish said then your window glass cracks and windows won't open ...true story ...I'm in construction in Canada yes different but principles same..
 

Mauricio

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Nov 18, 2002
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n that case he probably, if he did things right slid a 1/4 steel plate across the top of the window. if not in a few more years you will start to see visible cracks in that area and then at that time a beam will have to be plate will have to be installed or something!
Der Fish

I had cracks pretty fast but only the part that he filled up. I actually hadn't enlarged the opening but had it moved to the center of the wall and enlarged. The cracks appeared where the old window was. This was all five years ago and the window still opens fine, but I know the guy is not the best maestro in town.
 

lifeisgreat

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Sounds like your fine ...more like a mortar consistency or dried to fast from sun or Heat issue then a fail from load bearing..
 

reilleyp

Well-known member
Dec 12, 2006
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I had cracks pretty fast but only the part that he filled up. I actually hadn't enlarged the opening but had it moved to the center of the wall and enlarged. The cracks appeared where the old window was. This was all five years ago and the window still opens fine, but I know the guy is not the best maestro in town.

If he moved your window to the left, and did not install another lintel, or reinforce with rebar, then you may have drilled a hole in the worst possible location. You should borrow a metal detector to see if you can find any steel in that opening. In the DR, you could have many poor construction choices above that window.

See page 105.

https://www.sheltercluster.org/sites/default/files/docs/2015_confined_masonry_guide_sdc_eeri.pdf
 

lifeisgreat

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Here's an idea run a strong magnet along under ledge if it sticks you got steel and go across length...