# Forum Home Renovation The Garden Shed  Framing new windows in old(ish) steel shed.

## Mike-B

Hi guys,  
I'm converting a 9x3m section of a larger 18x9m steel farm shed for use as a break room. 
In the process we are adding a couple of 1.5x1.2m windows and a glass sliding door. We are framing out the inside with timber but the size of the windows and doors means the purlins in the shed will need to be cut and framed as well. Here is lies my problem: The shed is 20 years old and the gal C purlin used is 85mm x 45mm. I cannot find a purlin of the same dimension anywhere and using larger or smaller dimensioned steel seems like it would make things difficult to line-up. 
It was suggested I could use some of the 90x45 structural timber I have but its treated (H4 seasoned) and I'm worried about the corrosion between an external zincalume wall and timber. Could I use this and perhaps just face the timber with flashing tape? 
Cheers,

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## The Roofer

Hi Mike, 
There would be no problems between the ZincAlume cladding and the timber (H4 treated) - the only worry is between the old GAL purlins and the ZincAlume sheets if you have water penetration! You won't find a purlin today of that dimension - unless specially rollformed (cost plus) so timber is definitely your best option. Use flashing tape to stop the noise from the sheet movement in hot to cold temperature changes - but otherwise go right ahead.

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## Shedblog.com.au

Another option could be Lysaght 90mm x 35mm Plate or 90 x 65mm plate available in 7.5m lengths.  It might cap the 85mm purlin reasonably well.  If you do use the treated timber try to isolate it's contact with steel as much as possible and use a well coated fastener.

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## Mike-B

Cheers for the replies fellas. I had looked at the Lysaght steel as an option but I think it's going to be just as easy with the timber I already have. My local steel guy had also offered the option of a custom rollform but we both laughed at the potential price and minimum order. 
I would have thought I'd see some signs of Gal/Zinc corrosion already considering the shed is 20+yrs old but so far so good.  The bulk of the treated stud framing will be separated from the purlins via the Anticon sandwiched in-between.  
I just scored 30m of that adhesive flashing tape for the princely sum of doing-a-favour for a mate so I think I'm all sorted... for now.  :Wink:

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## Shedblog.com.au

Sounds good, have fun with the fit out, cheers, Dave

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