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Hello from Hobart Tasmania. I have purchased 1930's weatherboard cottage with a tin roof. The roof is insulated in the main part of the house (i.e., in the attic) but the additions on the house are not insulated - there is no attic on these extensions, just the roof immediately above the rooms. As a result, these extension areas are very hot in summer and extremely cold in winter.

Recently, when we were getting a quote on insulating in the crawl space below the house, an insulator company suggested that they could simply 'remove' the tin roof above the extension, install fiberglass, and re-attach the tin.

It seemed like a reasonable way forward to make these rooms more useable - but I am curious if there is anything I need to be wary of or concerned about. Is is OK to simply remove tin, add insulation, and re-attach tin? Do I need to worry about anything else, such as potential new leaks on roof from removing the tin? Do I need to worry about moisture from the house causing rot?

Any clues would be most appreciated! I have no experience with any thing like this at all!

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Can you see the underside of the tin roof in the additions? Or is the ceiling faced with drywall, etc.? If it's unfaced, you could have spray-in insulation installed. Or it might be easier to remove the ceiling, insulate, and put the ceiling back. –  longneck Jan 13 at 17:28
    
Hi there, You can't see the tin...there is drywall on the ceiling face... –  Janet Jan 13 at 22:49
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1 Answer

What they are suggesting is done in metal buildings in the USA, the insulation is wrapped in a type of plastic sheeting on all sides, it is made that way. It is also in large rolls and very wide, maybe 3-4ft?

My biggest concern would be the distortion of the metal when it comes to removing it. If the roof is attached with screws, you have a small chance of salvaging the roofing. If the roof is fastened with nails, the metal will surely be distorted. The fasteners to reattach the roofing, which should be screws with neoprene washers, rely on a flat surface, if it is a newer system. The refastening may not take well if care is not taken on the removal. Of all the fasteners in any given roof it will only take one to create leak, with the insulation in place and it's plastic layer, it would be hard to tell where a leak may really be or if any evidence is visible until it is too late. I refer to wet, or rotted framing after a time.

If it is the older system where the nails are driven through the standing rib, and the nail has a lead coating to conform and seal the hole from the nail,, DO NOT let them remove it unless a new roof goes back down. It may be better to insulate from the underside, even if it may be finished. enter image description here

This is a sample of what I was going to suggest, It may cost more overall, but it is the metal roof and insulation combined. It will not compress like the fiberglass will and give a higher R rating

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Thank you so much Jack. I will have a look tonight at how the tin is fastened. Would the problem be 'solved' if we simply purchased new tin to put back on top? (It is impossible to do from the inside, as the rooms are finished with plaster on the inside roof). –  Janet Jan 13 at 1:12
    
To have a picture of the roof would be good, the removal of the integrity roof, depends on how it is made to begin with, but a new roof would surely keep the issue of leaks to a minimum. The only reason I say it that way, is it now depends on the quality of workmanship. The new material will remove a potentially weak link. I will add suggestions in the answer box to give some insight on examples of insulation. –  Jack Jan 13 at 1:47
    
I overlooked what may be one very important question, is this a standing seam roof where the fasteners are concealed? The picture would be good on this. –  Jack Jan 13 at 2:09
    
Hi again Jack,I can try and get a picture for you. Not sure how I load it up onto this site...but maybe I can e-mail you directly if that would help you? –  Janet Jan 13 at 22:48
    
For the sake of the site, for future reference if somebody has the same question, it is better to upload the pic online. Save the picture In a place you can retrieve easily, like your desktop for example. Go to your question, at the bottom there is an edit link, click on that. Place your mouse cursor where you want the picture to show up in the question, get it to blink there. At the top of the text box, there is a square blue icon at the top, that is a link to upload pictures with. Click on that, click on browse, point it to where you saved the picture, and click upload. –  Jack Jan 14 at 1:45
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