Raindrop sounds on copper clad sill 1

[Zygnoth]

Hi everyone,

I've been asked to take a look at a problem in an existing building for a friend of mine but I'm not sure of any immediate solutions and thought this would be a good place to ask.

The building is copper-clad with the seams running vertically on the building. I'm not certain who designed the building in the first place but they seem to have forgotten to put an rain drips at the top of window opes (for aesthetics?). The problem is that when it rains, the water travels down the facade, drops off when it reaches the top of the window ope and lands heavily on the window sill.

I can't think of any immediate solution but had some basic ideas:
1. A neoprene membrane on the top of the sill. This could have problems with it becoming saturated and sounding just as loud as the metal.
2. Timber sill replacement solidly fixed to the structure. This would have the sound as well but would be deadened as the timber would transmit vibrations into the building. This method could be replaceable as well in the future.
3. Infill under existing metal sill - type of sealant that would join the metal on to the structure below. I'm not sure this would work as areas between sealant would still be just as loud.

I know this is an unusual problem but please let me know if you have come across anything suitable before.

I've attached a .png which might clarify some of the issues...

Thanks,
Z

 

[Ron]

Why can you not retrofit a head flashing? Since it is copper, it could be soldered in place. As an alternative, a copper flashing could be mechanically fastened and sealed with sealant.

Considering the designer's lack of awareness of flashings, I wonder if you have water finding its way inside the copper cladding and causing damage that you can't see. I would do further investigation on this one.

Is the window frame isolated from the copper? Do you have dissimilar metals in contact?

Are the standing seams intact and how are they formed?

 

[Zygnoth]

Hi Ron,

Thanks for the message. I'm not certain I can answer all your questions without going back to visit the building. I'm actually going to be in the area around Wednesday/Thursday so might take a call in.

I don't think that there are any problems with the flashing - I visited the site a long time ago (15 months or so) before there were any fittings in place and I don't recall seeing any wetness. I'm assuming the construction from internal to external is:

- insitu concrete wall
- insulation
- weatherproof membrane
- copper cladding

The window frame is plastic if I remember correctly so I don't think there will be any bimetallic corrosion taking place...my memory of the building is that there was no corrosion taking place. I think the architects/builders did a good enough job sealing up the building but failed to consider the implication of raindrops on the sills.

I like the idea of the soldered head flashing but I don't know what type of insulation is being used (if it would react to the heat) so mechanical fixings and sealant may be a safer bet.

Do you think the sill itself is a lost cause - will there always be a heavy sound off the metal?

When I was thinking of the problem first, I couldn't recall seeing too many copper sills in my experiences - I think I might know the reason now!

 

[Debaser]

Somewhat facetious, but is this just another reason to require architects to live/work in their creations for six months or so after opening?

 

[Zygnoth]

In an industry which is always pushing for innovation, I'm surprised so much goes right during building jobs!