The Forestry Forum

General Forestry => Timber Framing/Log construction => Topic started by: Ladysmith on March 27, 2016, 10:20:02 PM

Title: Full log rafter spacing.
Post by: Ladysmith on March 27, 2016, 10:20:02 PM
Hello all, I am new to forestryforum so please bear with me. I have a cabin ( black spruce)in the far north and the area gets a lot of snow. I want to replace the 4 pitch roof with a 10/12, insulate it and have room for a loft. The cabin is 14x20.
My plan is to use 8 inch log rafters, then deck with
2x6 TNG, put 4 inch r-tech on top then 5/8 OSB, then shingle. My question is, can I space some of the rafters at 6 feet on center but mostly at 4 feet. thanks.
Title: Re: Full log rafter spacing.
Post by: Magicman on March 28, 2016, 08:29:09 AM
Hello Ladysmith, and Welcome to the Forestry Forum.  Adding your location to your profile always helps with questions.   ;)
Title: Re: Full log rafter spacing.
Post by: DDW_OR on March 28, 2016, 01:04:13 PM
I do not know the rafter spacing needed.
shingles? why not a metal roof. snow slides off, and less danger from a wildfire ember landing on the roof and catching it on fire. and i think cheaper insurance?

here are some rafter calculating sites i used for my barn

http://www.awc.org/codes-standards/calculators-software/spancalc
http://www.blocklayer.com/Roof/RafterEng.aspx
http://www.blocklayer.com/Roof/RoofEng.aspx
http://www.hsh.k12.nf.ca/technology/cmhc/english/book/appendix/table26/index.htm
Title: Re: Full log rafter spacing.
Post by: Ladysmith on March 28, 2016, 06:28:01 PM
Thanks for the response and recommendation of metal roof. M CH appreciated.
Title: Re: Full log rafter spacing.
Post by: pabst79 on March 28, 2016, 08:37:38 PM
I can't help on spacing as I would just be guessing, but I 2nd the idea of a metal roof. Less chance of fire and it will last a lifetime. Shingles made today regardless of "lifetime" warranty are a pain in the rear. What part of Ontario is your cabin in?
Title: Re: Full log rafter spacing.
Post by: Ladysmith on March 29, 2016, 05:20:45 AM
Thanks for the metal recommendation. I will be using it. I am 148 miles north of International Falls/ Fort Frances. Closest town is Dryden, Ontario.
Title: Re: Full log rafter spacing.
Post by: Heartwood on March 29, 2016, 08:47:53 AM
"Log Span Tables" book for sizing round joists, beams and rafters is available from the International Log Builder's Assn.  http://www.logassociation.org/resources/publications.php (http://www.logassociation.org/resources/publications.php).
You would need to know the snow load, which I suspect is pretty high up there, and the species of wood for the rafters.
Title: Re: Full log rafter spacing.
Post by: Ladysmith on March 29, 2016, 08:19:53 PM
Heartwood,
Thanks for the link. I am using black spruce 8" with a 55# snow load so hopefully I can match to the tables you reference.  Rich.
Title: Re: Full log rafter spacing.
Post by: pabst79 on March 31, 2016, 09:11:01 AM
When I was a kid we used to stay in Dryden on the way to Pickle lake, now the roads are better going up the North shore, so we go through Ignace. Its unbelievable fishing no matter were you go. Good Luck with the cabin!

Josh