5/8" vs 1/2" Sheetrock/Blueboard

I am renovating an 1870s house in MA and started by gutting a small bedroom on the 2nd floor. After insulating, I plan to install blueboard with veneer plaster. I have read DIY books, Building codes and these discussion groups but I cant figure out whether I need 5/8" or 1/2" blueboard. I guess it depends on local building codes and where the room is located, but I am wondering what the rule of thumb is? 1/2" blueboard is readily available, while I would need to go to a commercial dealer to get 5/8". Which brings up another question....does 1/2" blueboard/sheetrock plus the 1/8" veneer count as the 5/8? Any thoughts would be appreciated.
Thanks
Joe
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Where I live 5/8 is used on both sides of a wall for a fire wall. Like between the garage and the home.
1/2 is used for all other applications. Unless your local authority has a requirement for "blue board" I would only use it when it was near water or high humidity, like the kitchen or bathroom.
No half inch with a coat of plaster is not considered 5/8 where I live.
Best check with the building gurus where you live.
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Thanks...that helps! I have heard of using 5/8" between a garage and home...what are other places where a "fire-wall" is required?
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In a residence? No other areas that I am aware of. Speaking about single family detached housing.
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Boiler room (if you've got one) and some types of furnace rooms. This might just be for rental properties, though.
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SQLit wrote:

Note: The IRC allows 1/2" now instead of 5/8" on a firewall. However your state may not have adopted the IBC yet.
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Joe wrote:

Your post doesn't indicate why you think you need 5/8". 1/2" should suffice.
Also, here's an excellent primer about wallboard(s) and the reason why blueboard *should* be used for your veneer.
http://www.wconline.com/CDA/ArticleInformation/features/BNP__Features__Item/0,3299,83959,00.html
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G Henslee wrote:

http://www.wconline.com/CDA/ArticleInformation/features/BNP__Features__Item/0,3299,83959,00.html
Thanks for that. Scratching around in the back of my mind was a vague recollection that 5/8 rock is required on ceilings. Last time I had need for that was over 30 years ago. I see I was right but that there is a 1/2" product that is a 5/8 equivalent.
Harry K
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Thanks for all the info!
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