ᐅ Core Drilling / Installation of Kitchen Ventilation / Assessment of Workmanship
Created on: 29 Jun 2025 17:50
M
Mike_EfDear community,
We have purchased a single-family house in which we had a new kitchen installed. Based on a family recommendation, we hired a contractor (with over 20 years of experience) who runs a home construction company (1 employee) to do the following:
- Core drilling for a 15 cm (6 inch) diameter exhaust duct for the kitchen range hood
- Construction of a drywall enclosure from the drill hole to the range hood
including installation of the aluminum flexible duct (due to tight angles, a round or square rigid duct was not possible)
Implementation:
The contractor drilled a 15 cm (6 inch) diameter hole through the exterior wall. At that time, I was not aware of the exact size of the hole. However, I clearly communicated that the exhaust duct should be 15 cm (6 inches). When installing the wall box I had provided, it obviously did not fit because the core drill hole would have needed to be larger. Therefore, the project was changed to a 12.5 cm (5 inch) exhaust duct. I also noticed that when laying the aluminum flexible duct, he simply stretched it apart, although the packaging clearly showed it should be stretched while rotating to avoid tearing.
It must also be mentioned that during the core drilling he damaged a cable, even though he had been warned beforehand that a cable runs inside the wall. We had the cable repaired ourselves by a known electrician.
Since (naively on our part without intervening) further work was not done properly, we are now so frustrated that the following questions arise for the experts in this forum:
1) Do we have to accept the smaller core drill diameter? The range hood now permanently operates with less power because it can simply exhaust less air due to the 12.5 cm (5 inch) diameter instead of 15 cm (6 inch). Should something else have been communicated, for example: “The exhaust system must be operated with a 15 cm (6 inch) duct, meaning the core drill hole must be larger accordingly, as specified by the wall box manufacturer”? I generally assume that a “building professional” with many years of experience knows that the drill hole must be larger than the duct diameter!?
2) If we wanted to enlarge the core drill hole (which of course would now involve significant effort since the kitchen is already installed), would that even be possible? If so, how could that be practically done? Remove part of the drywall? Take down the wall cabinets? Position the core drilling machine at hopefully the correct height and angle and drill through again?
3) The installation of the profiles for the enclosure was done well, but there are visual issues:
- The joint between two drywall panels is visible – I suspect the joint compound was not applied properly and was pulled into the gap
- Additionally, there are grooves visible in parts of the enclosure – likely caused by trowel marks that were left unfinished
--> See question 4)
4) Given the above points, would a reduction in the paid service be justified? Should we even consider quantifying the damages (damaged cable, reduced performance of the range hood) against the contractor?
Thank you in advance for your feedback and experience. As you can see, we had no previous experience and were therefore “at the mercy” of the above approach.
We have purchased a single-family house in which we had a new kitchen installed. Based on a family recommendation, we hired a contractor (with over 20 years of experience) who runs a home construction company (1 employee) to do the following:
- Core drilling for a 15 cm (6 inch) diameter exhaust duct for the kitchen range hood
- Construction of a drywall enclosure from the drill hole to the range hood
including installation of the aluminum flexible duct (due to tight angles, a round or square rigid duct was not possible)
Implementation:
The contractor drilled a 15 cm (6 inch) diameter hole through the exterior wall. At that time, I was not aware of the exact size of the hole. However, I clearly communicated that the exhaust duct should be 15 cm (6 inches). When installing the wall box I had provided, it obviously did not fit because the core drill hole would have needed to be larger. Therefore, the project was changed to a 12.5 cm (5 inch) exhaust duct. I also noticed that when laying the aluminum flexible duct, he simply stretched it apart, although the packaging clearly showed it should be stretched while rotating to avoid tearing.
It must also be mentioned that during the core drilling he damaged a cable, even though he had been warned beforehand that a cable runs inside the wall. We had the cable repaired ourselves by a known electrician.
Since (naively on our part without intervening) further work was not done properly, we are now so frustrated that the following questions arise for the experts in this forum:
1) Do we have to accept the smaller core drill diameter? The range hood now permanently operates with less power because it can simply exhaust less air due to the 12.5 cm (5 inch) diameter instead of 15 cm (6 inch). Should something else have been communicated, for example: “The exhaust system must be operated with a 15 cm (6 inch) duct, meaning the core drill hole must be larger accordingly, as specified by the wall box manufacturer”? I generally assume that a “building professional” with many years of experience knows that the drill hole must be larger than the duct diameter!?
2) If we wanted to enlarge the core drill hole (which of course would now involve significant effort since the kitchen is already installed), would that even be possible? If so, how could that be practically done? Remove part of the drywall? Take down the wall cabinets? Position the core drilling machine at hopefully the correct height and angle and drill through again?
3) The installation of the profiles for the enclosure was done well, but there are visual issues:
- The joint between two drywall panels is visible – I suspect the joint compound was not applied properly and was pulled into the gap
- Additionally, there are grooves visible in parts of the enclosure – likely caused by trowel marks that were left unfinished
--> See question 4)
4) Given the above points, would a reduction in the paid service be justified? Should we even consider quantifying the damages (damaged cable, reduced performance of the range hood) against the contractor?
Thank you in advance for your feedback and experience. As you can see, we had no previous experience and were therefore “at the mercy” of the above approach.
I will write from a kitchen planning perspective only:
This should have included sharing the planned wall sleeve and its specifications, rather than simply requesting a 15cm (6 inches) diameter.
Regarding the flexible duct… the planning should definitely have been reviewed or adjusted, and the use of flexible ducting avoided.
Since we don't know the location and surrounding conditions, how are we supposed to assess that?
Mike_Ef schrieb:
Core drilling for a 15cm (6 inches) diameter exhaust duct of the kitchen range hood
This should have included sharing the planned wall sleeve and its specifications, rather than simply requesting a 15cm (6 inches) diameter.
Regarding the flexible duct… the planning should definitely have been reviewed or adjusted, and the use of flexible ducting avoided.
Mike_Ef schrieb:
If the core drilling were to be enlarged (which, of course, would now involve significant effort since the kitchen is already installed), would that even be possible?
Since we don't know the location and surrounding conditions, how are we supposed to assess that?
N
nordanney30 Jun 2025 09:13Mike_Ef schrieb:
commissioned the following:
- Core drilling for a 15cm (6 inch) diameter exhaust vent for the kitchen range hood Was a 15cm (6 inch) hole commissioned or was it clearly communicated that the wall box has a 15cm (6 inch) diameter and must fit into the drilled hole?
Mike_Ef schrieb:
I had clearly stated that the exhaust vent should be 15cm (6 inch). When installing the wall box I provided, of course it did not fit because the core drill hole should have been larger. That’s why they switched to a 12.5cm (5 inch) exhaust vent. Why? It would have been no problem to enlarge the hole, right? So you accepted the 12.5cm (5 inch) size in agreement with the contractor.
Mike_Ef schrieb:
It should also be mentioned that during the core drilling the contractor drilled through a cable, even though he was previously informed that a cable runs in the wall. What else could the contractor have done? The cable doesn’t just disappear.
Mike_Ef schrieb:
We had the cable repaired by an electrician we know ourselves. Why not by the contractor? That must have involved quite some chasing in the wall and rerouting.
Mike_Ef schrieb:
Furthermore, I noticed that when laying the aluminum flexible duct, he simply pulled it apart, although the packaging clearly showed that it should be twisted while pulling to avoid tearing. And? Did the duct tear or not? If not, then it shouldn’t bother you.
Now a few comments on your questions:
1: You already agreed this with the contractor! You even provided a smaller wall box yourself.
2: Sure. Make space and drill again. Basically doing the whole job over.
3: Unfortunately, I don’t see the issues. The pictures are not showing up for me, so I can’t comment on that.
4: I would talk to the contractor. But charging for damage due to the hood’s insufficient performance? I don’t see that. Also, I cannot see the hood’s specifications; they are not showing up for me either.
125mm (5 inches) is too small for modern range hoods. Yes, it will work, but you will lose the warranty because wear and tear is significantly higher. It is also likely to be much louder.
If you order 150mm (6 inches), that is what you will get. You should have taken action when you realized the hole was too small.
The cable would have been in that position anyway. Or would you have preferred the hole to be moved? In that case, you would have needed to inform the builder.
If you order 150mm (6 inches), that is what you will get. You should have taken action when you realized the hole was too small.
The cable would have been in that position anyway. Or would you have preferred the hole to be moved? In that case, you would have needed to inform the builder.
Good evening,
thank you very much for the feedback.
I would like to respond as follows:
It was clearly stated what was planned. Of course, I did not say that I wanted a 15 cm (6 inch) hole, but that the exhaust air should be operated with a 15 cm (6 inch) pipe. By the way, the wall duct was at hand. It was immediately noted that the hole was too small. So the correct procedure would have been for me to read the installation instructions and tell him how big the hole should be (in this case at least 16.2 cm (6.4 inches)). Even with a diameter of 12.5 cm (5 inches), a drilled hole of 15 cm (6 inches) is too large. In this respect, I consider the 15 cm (6 inch) hole to be professionally incorrect.
I would also like to point out that there is no wall duct for a 15 cm (6 inch) hole, at least according to my research. I confronted the tradesman with this at the time; the reaction was "Oh, I see."
It was not communicated to me that this could be done so easily. On the contrary. Hence my inquiry here. Due to the pressure caused by the kitchen delivery, I agreed to take a wall duct for a 12.5 cm (5 inch) exhaust.
I now see that this was a mistake on my part! In a way, it can be considered as consent.
It would have been possible to simply drill 1 cm (0.4 inch) further next to it, which I had pointed out.
Correct. It was not done because the guy is not an electrician, and I know one privately who took care of it – by the way, we did not get any discount on the bill for this. Also, there was time pressure due to the kitchen delivery.
Thanks for the summary. Clear and precise. Great 🙂
It is indeed the case that the hood is approved for 12.5 cm (5 inch) or 15 cm (6 inch). However, it had to be used with a reducing adapter from the hood to the 12.5 cm (5 inch) hose. I think the warranty should be valid, but I am not sure.
I would have preferred that too, but unfortunately it was not possible due to the structural conditions.
Overall, many thanks for the helpful suggestions!
thank you very much for the feedback.
I would like to respond as follows:
nordanney schrieb:
Was a 15 cm (6 inch) hole commissioned or was it clearly communicated that the wall duct has a diameter of 15 cm (6 inches) and must fit into a drilled hole?
It was clearly stated what was planned. Of course, I did not say that I wanted a 15 cm (6 inch) hole, but that the exhaust air should be operated with a 15 cm (6 inch) pipe. By the way, the wall duct was at hand. It was immediately noted that the hole was too small. So the correct procedure would have been for me to read the installation instructions and tell him how big the hole should be (in this case at least 16.2 cm (6.4 inches)). Even with a diameter of 12.5 cm (5 inches), a drilled hole of 15 cm (6 inches) is too large. In this respect, I consider the 15 cm (6 inch) hole to be professionally incorrect.
I would also like to point out that there is no wall duct for a 15 cm (6 inch) hole, at least according to my research. I confronted the tradesman with this at the time; the reaction was "Oh, I see."
nordanney schrieb:
Why? It would have been no problem to simply enlarge the hole, right? So you accepted the 12.5 cm (5 inch) size in agreement with the tradesman.
It was not communicated to me that this could be done so easily. On the contrary. Hence my inquiry here. Due to the pressure caused by the kitchen delivery, I agreed to take a wall duct for a 12.5 cm (5 inch) exhaust.
I now see that this was a mistake on my part! In a way, it can be considered as consent.
nordanney schrieb:
What should the tradesman have done? The cable does not just disappear.
It would have been possible to simply drill 1 cm (0.4 inch) further next to it, which I had pointed out.
nordanney schrieb:
Why not done by the tradesman? That would require a proper chase and reinstallation.
Correct. It was not done because the guy is not an electrician, and I know one privately who took care of it – by the way, we did not get any discount on the bill for this. Also, there was time pressure due to the kitchen delivery.
nordanney schrieb:
Now a few words about your questions:
Thanks for the summary. Clear and precise. Great 🙂
FloHB123 schrieb:
125 mm (5 inches) is too small for current extractor hoods. Yes, it works, but you lose the warranty because wear is significantly higher.
It is indeed the case that the hood is approved for 12.5 cm (5 inch) or 15 cm (6 inch). However, it had to be used with a reducing adapter from the hood to the 12.5 cm (5 inch) hose. I think the warranty should be valid, but I am not sure.
kbt09 schrieb:
Regarding the flexible duct ... the planning should definitely have been revised or adjusted and the flexible duct avoided.
I would have preferred that too, but unfortunately it was not possible due to the structural conditions.
Overall, many thanks for the helpful suggestions!
Mike_Ef schrieb:
I would have preferred that as well, but unfortunately it wasn’t possible due to the building conditions.I find that hard to believe; perhaps an adjustment in the planning would have been advisable. In any case, the hood suffers a performance loss from having only 12.5 cm (5 inches) of exhaust combined with flexible ducting.Mike_Ef schrieb:
By the way, the wall vent box was on hand.Did you give it to the contractor before drilling the hole?Similar topics