Galvanic reaction between Aluminium and Galvanised sheets if any.

[gordon_s1942]

We're in the process of repairing a shed/garage/storage and I have several 'preloved' Aluminium windows and I thought of installing them into the shed walls for light and ventilation.
While we dont want it to look like the Taj Mahal, neither do we want it to be an eyesore either.
The shed walls are galvanised/zincalum custom orb (corrogated) iron of varing age and I wondered if there are any precautions needed apart from general waterproofing when using disimilar metals together.
There is no timber being used in the repair for framing, its all 'C' shaped Galvanised purlins and pipe construction but there is no reason why timber or any other material cant be used as long as its exposure to weather is minimised to frame in the windows.
This shed is being repaired by that well known family group called 'Jerry' and using the expertise of the Dodgey Bros (son and friend) as designers and builders.
I simply stand offering rarely well received gratuitous suggestions while maintaining a safe distance from any actual effort in assisting them so all advise on my query is welcomed.

[beer4life]

We're in the process of repairing a shed/garage/storage and I have several 'preloved' Aluminium windows and I thought of installing them into the shed walls for light and ventilation.
While we dont want it to look like the Taj Mahal, neither do we want it to be an eyesore either.
The shed walls are galvanised/zincalum custom orb (corrogated) iron of varing age and I wondered if there are any precautions needed apart from general waterproofing when using disimilar metals together.
There is no timber being used in the repair for framing, its all 'C' shaped Galvanised purlins and pipe construction but there is no reason why timber or any other material cant be used as long as its exposure to weather is minimised to frame in the windows.
This shed is being repaired by that well known family group called 'Jerry' and using the expertise of the Dodgey Bros (son and friend) as designers and builders.
I simply stand offering rarely well received gratuitous suggestions while maintaining a safe distance from any actual effort in assisting them so all advise on my query is welcomed.

Preventing galvanic corrosion

There are several ways of reducing and preventing this form of corrosion.
One way is to electrically insulate the two metals from each other. Unless they are in electrical contact, there can be no galvanic couple set up. This can be done using plastic or another to separate steel water pipes from copper-based fittings or by using a coat of grease to separate aluminium and steel parts. Use of absorbent washers that may retain fluid is often counter-productive. Piping can be isolated with a spool of pipe made of plastic materials or made of metal material internally coated or lined. It is important that the spool has a minimum length of approx 500 mm to be effective.
Another way is to keep the metals dry or shielded from ionic compounds (, , ), for example by painting or encasing the protected metal in plastic or epoxy, and allowing them to dry.
Coating the two materials or if it is not possible to coat both, the coating shall be applied to the more noble, the material with higher potential. This is necessary because if the coating is applied only on the more active material, in case of damage of the coating there will be a large cathode area and a very small anode area, and for the area effect the corrosion rate will be very high.
It is also possible to choose metals that have similar potentials. The more closely matched the individual potentials, the lesser the and hence the lesser the galvanic current. Using the same metal for all construction is the most precise way of matching potentials.
or other plating can also help. This tends to use more that resist corrosion better. , , silver and can all be used. Galvanizing with zinc protects the steel base metal by sacrificial action.

[allover]

Industrial rooves, you can have galvanised roofing draining into zincalum gutters, reverse the process and the gutters will last about 3 years!! best of all is colorbond gutters (3 coats of paint and then the zinc to get thru)

[fromaron]

Zincalum and Aluminium are very close materials with almost the same Anodic +VE values and therefore galvanic currents shouldn't really exist.
Look at site for compatibility chart.
Just to make sure you fulfil your duties as the SUPERVISOR make sure there are no cavities in between two materials exist where water can accumulate and stay for prolong period of time. Just get them to fill all the cavities with silicon for example, that will ensure no corrosion happens for a long time.

[tytower]

Colourbond roofing and sides and Zincalume roofing and sides have been used with aluminium windows for decades since each came out .
All dis-similar metals have corrosion going on between them but it needs water and salt water is the worst so you will see the worst corrosion down by the seaside.

Wouldnt warrant special anti corrosion measures just regular maintenance

[lsemmens]

The question is, HOW LONG, do you intend to stay in the property? (I'm one of the original bros ) If only a short time, then do what you see as the easiest solution. If you want it to be around for ever and a day, then, obviously more care needed. The comments by allover, above, about Galv/Zinc are exactly correct but if it's easy to isolate, then do so.

[allover]

Not if water sits in the gutters for periods of time, i found this out when i ordered zn/alum box gutters for an industrial roof, the bastard sheetmetal shop stuffed up and delivered galvanised box gutters, It looked suspicous but hard to tell so wacked them in, 3 years later the galvanising was burning off leaving rusted metal

[tytower]

If you mix galvanised sheets and zincalume sheets on a roof they will corode where they touch but its the water between different metals that does it

[tytower]

Bit late now but I should have said I get over this problem by attaching timber reveals and plastic weather stripping to the alum windows and screwing the steel sheets to the timber. No corrosion at all