ᐅ Potential defects in installed mechanical ventilation ductwork – concreting will be done today

Hello everyone,

I urgently need an assessment from someone with some experience in controlled residential ventilation, specifically regarding the installation.

Yesterday afternoon, the ducts were installed in the ceiling, the upper layer of reinforcement steel is currently being placed, and the concrete will be poured this afternoon.

Last night, I went through all the lines to check if everything looks okay. I found two issues:

1. Hole in the duct: however, it’s not possible to see inside the pipe, so I assume the duct has both an outer and inner wall and the hole does not penetrate the inner wall. My question is how serious this is: does this section of duct need to be replaced, is simply sealing it with strong tape like duct tape sufficient, or is this only cosmetic and can be concreted over as is?

2. Valve wrapped with tape: unlike the other valves, this duct in the valve is additionally wrapped with tape, and while the other valves have the second connection sealed with a plastic cap, this one uses tape. I assume a locking mechanism is damaged and the original cap is missing. Here again, how serious is this: does the valve need to be replaced, or is this just a pragmatic fix that can be left as is?

Unfortunately, my installer has been unreachable since yesterday late afternoon and according to the office is out all day today. The office is trying to reach him and has the photos I sent yesterday, but I’m thinking about what to do if the concrete arrives this afternoon before the installer can respond. If necessary, I may have to seal the hole myself with duct tape, which is better than nothing. Also, I’m worried that more holes might appear after the upper reinforcement layer is installed, which I would then have to address.

Thanks for your help.

This is not critical at all. As you noticed, there is an inner and outer pipe. You can repair it again with duct tape if needed, but it shouldn’t cause any problems as it is.

For the valve, a cover would obviously be the right solution, but the current setup will hold. The pipe was probably not properly sealed, which is why the tape is there and the other end is exposed due to the missing cover. You can open it again, place a piece of styrofoam in front of it, and then seal it again with tape.

You probably won’t be able to find a cover quickly anyway.

Thanks for the reassuring information. 🙂

The manager has now had the office assistant inform us that the hole looks unsightly and someone will come to patch it before the concrete is poured this afternoon.

However, everything is fine with the valve. Maybe the valve cover is also underneath, as it sits 5cm (2 inches) further inside, but I didn’t want to check since that would have meant breaking the seal.

I would be more concerned about the pipes being installed inside the ceiling rather than on top of it, but I suppose that has become common practice nowadays. Aside from that, the pipe will still be fully encased in concrete. So what could possibly go wrong? It will definitely be airtight then.

Good luck

K1300S

Why worry?

Calculations have surely been done, and the pipes are usually secured in concrete, so where is the problem?

K1300S schrieb:
I would be more concerned about the pipes being embedded inside the ceiling slab rather than just on top of it, although that seems to be common practice nowadays. Apart from that, the pipe will be fully encased in concrete. So what could possibly happen? It will definitely be airtight then.

Good luck

K1300S

In new builds, from what I’ve researched, it’s much more common for pipes to be fully encased in concrete rather than laid on top of the slab.

What could happen? Concrete could leak in if it wasn’t properly sealed or patched. I just received a call confirming that the hole has been patched and indeed had to be patched. So I’m relieved for now. 🙂