Hello,
a multisplit air conditioning system was installed in the attic of our house (built in 1993). The work was done very neatly, with the pipes routed through the attic, and the system is working perfectly.
One thing has been bothering me a bit, though. The installer drilled the holes through the drywall from below. In the living room, he hit a load-bearing beam and drilled a side hole into it from below. From the attic, he then drilled sideways from the edge into the hole made from below, creating an almost 90° channel through the beam, or rather along the edge inside the beam.
The beam dimensions:
Width: 155mm (6 inches)
Height: 330mm (13 inches)
Length: 5,800mm (19 feet)
The hole diameter is 75mm (3 inches).
My gut feeling says it should be okay, since the hole is only 75mm (3 inches) wide/deep into the beam, and the height of the penetration from below is roughly 110mm (4.3 inches).
Attached you will find a photo and a rough cross-section of the area. The photo was taken the day before the air conditioning pipes were installed. The attic floor is made of cold flooring.
What is your opinion? My assessment is that since the entire width of the beam was not drilled through—roughly half of the width is still fully intact—and the beams above (indicated in the section) essentially rest on the intact half of the beam, this should be acceptable.
(Blue = load-bearing beam, red = drilled area, brown = beam diagonally above)
As I said, drilling through the full 155mm (6 inches) width would certainly be a different matter.
Nothing has occurred in the last two weeks since installation—no cracks in the drywall below, etc.
It is also important to mention that this location is quite close to the start of the beam (about 300mm (12 inches) from the end), so not in the middle of the span.
What do you think?
Edit: The hole is located precisely at the beam’s edge, as indicated in the section. It goes 75mm (3 inches) into the 155mm (6 inches) width, so about 80mm (3 inches) of width remains intact. The hole at the beam edge is approximately 110mm (4.3 inches) high, 75mm (3 inches) wide, and 75mm (3 inches) deep. The whole is located about 300mm (12 inches) from the support (or angle bracket on another beam).
a multisplit air conditioning system was installed in the attic of our house (built in 1993). The work was done very neatly, with the pipes routed through the attic, and the system is working perfectly.
One thing has been bothering me a bit, though. The installer drilled the holes through the drywall from below. In the living room, he hit a load-bearing beam and drilled a side hole into it from below. From the attic, he then drilled sideways from the edge into the hole made from below, creating an almost 90° channel through the beam, or rather along the edge inside the beam.
The beam dimensions:
Width: 155mm (6 inches)
Height: 330mm (13 inches)
Length: 5,800mm (19 feet)
The hole diameter is 75mm (3 inches).
My gut feeling says it should be okay, since the hole is only 75mm (3 inches) wide/deep into the beam, and the height of the penetration from below is roughly 110mm (4.3 inches).
Attached you will find a photo and a rough cross-section of the area. The photo was taken the day before the air conditioning pipes were installed. The attic floor is made of cold flooring.
What is your opinion? My assessment is that since the entire width of the beam was not drilled through—roughly half of the width is still fully intact—and the beams above (indicated in the section) essentially rest on the intact half of the beam, this should be acceptable.
(Blue = load-bearing beam, red = drilled area, brown = beam diagonally above)
As I said, drilling through the full 155mm (6 inches) width would certainly be a different matter.
Nothing has occurred in the last two weeks since installation—no cracks in the drywall below, etc.
It is also important to mention that this location is quite close to the start of the beam (about 300mm (12 inches) from the end), so not in the middle of the span.
What do you think?
Edit: The hole is located precisely at the beam’s edge, as indicated in the section. It goes 75mm (3 inches) into the 155mm (6 inches) width, so about 80mm (3 inches) of width remains intact. The hole at the beam edge is approximately 110mm (4.3 inches) high, 75mm (3 inches) wide, and 75mm (3 inches) deep. The whole is located about 300mm (12 inches) from the support (or angle bracket on another beam).
Thank you for your assessment. Even though the height in that area is basically reduced by about 110mm (4.3 inches)?
So, starting right at the edge on the bottom, there is a 75mm (3 inch) hole drilled 110mm (4.3 inches) into the beam. Then, from the side at the top end, it is drilled out with a 75mm (3 inch) hole. In other words, at this point, 110mm (4.3 inches) of the 330mm (13 inch) height and 75mm (3 inch) of the 155mm (6 inch) width are removed. This is all observed over a 75mm (3 inch) beam length, about 300mm (12 inch) away from the support.
Is that acceptable so far?
So, starting right at the edge on the bottom, there is a 75mm (3 inch) hole drilled 110mm (4.3 inches) into the beam. Then, from the side at the top end, it is drilled out with a 75mm (3 inch) hole. In other words, at this point, 110mm (4.3 inches) of the 330mm (13 inch) height and 75mm (3 inch) of the 155mm (6 inch) width are removed. This is all observed over a 75mm (3 inch) beam length, about 300mm (12 inch) away from the support.
Is that acceptable so far?
The 110 mm (4.3 inches) seem larger than they actually are structurally in that location. So close to the support, the area below hardly matters as long as everything above remains intact. The spot appears to be a very local intervention, nothing that seriously damages the beam.
Thanks for your assessment, that helps me sleep a bit more peacefully 😉.
In the end, it was luck in misfortune. It would have been better if the beam hadn’t been hit at all, but the fact that it was damaged so close to the support, and only right at the edge for about 75mm (3 inches) in diameter, 110mm (4.3 inches) vertically upward, was basically the "unintentional" best outcome that could have happened 😀.
In the end, it was luck in misfortune. It would have been better if the beam hadn’t been hit at all, but the fact that it was damaged so close to the support, and only right at the edge for about 75mm (3 inches) in diameter, 110mm (4.3 inches) vertically upward, was basically the "unintentional" best outcome that could have happened 😀.
Hi, I have one more question.
Besides bending, which is relatively low near the support, there is also shear.
This should be rather uncritical since about half the width still has the full height, and above the opening there is roughly 2/3 of the height remaining, right?
This is different from a full hole entirely going through the beam. Here, there is a vertical hole DN75 (3 inches nominal diameter) drilled 110mm (4.3 inches) deep into the beam from below, located right at the edge, about 30cm (12 inches) from the support.
Besides bending, which is relatively low near the support, there is also shear.
This should be rather uncritical since about half the width still has the full height, and above the opening there is roughly 2/3 of the height remaining, right?
This is different from a full hole entirely going through the beam. Here, there is a vertical hole DN75 (3 inches nominal diameter) drilled 110mm (4.3 inches) deep into the beam from below, located right at the edge, about 30cm (12 inches) from the support.
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