Author Topic: 20x30 stock, change roof pitch (collar ties)  (Read 5761 times)

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Offline deabob11

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20x30 stock, change roof pitch (collar ties)
« on: October 11, 2007, 05:04:27 PM »
Last Quesiton!!!!  We whould finish up this weekend.
I wondered if i could lower the pitch of the roof to leave 6'5" of headroom in the loft.
I have 15" from the loft floor to the top of the plate.   I am going with a ridge beam and rafters heald in place with simpson rafter ties 16oc.  the loft is just 3/4" TG plywood.
How high should the top of the ridge beam be from the loft floor to make this change?
This would put the bottom of the collar tie at 6'5" from the loft floor.
Any thought, or is it best to just follow the plans.  
I just want the roof to be a little safer for my brother and I to work on!

Offline John Raabe

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Re: 20x30 stock, change roof pitch (collar ties)
« Reply #1 on: October 11, 2007, 05:57:52 PM »
You can certainly lower the pitch. As for the exact measurements it is easiest to do with a chalk line and snap it out on the floor of the loft. Then cut a couple of rafters and try it out. When you like what you have use the rafters as a template.

I would suggest pushing the collar tie higher (if you can) to give some usable headroom. A door header is only 6'-8" and the minimum (code) for a habitable room is 7'-6". Of course, if you go too low there is nothing left for the loft ceiling and you cannot triangulate the rafters with a collar tie. In that case you may have to go with a structural ridge beam and forget the collar ties.

The 45ยบ roof slope gives the best trade-off, in my opinion, but it does require some extra care and planning when doing the roofing.
« Last Edit: October 12, 2007, 05:21:17 AM by jraabe »
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Offline glenn kangiser

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Re: 20x30 stock, change roof pitch (collar ties)
« Reply #2 on: October 11, 2007, 07:46:25 PM »
I think either steep pitch would require care so it probably doesn't matter too much.  I did the 12/12 on my car garage based on the little house plans and being careful with a forklift platform or scaffold below I was able to do it just fine.  I also hooked a ladder over the peak of the roof - 4' folded 90 degrees over the other side-- to work off of.
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Offline deabob11

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Re: 20x30 stock, change roof pitch (collar ties)
« Reply #3 on: October 17, 2007, 05:48:04 AM »
thanks for the help.  i ended up trying a 9/12 pitch thinking that i would be able to roof that myself.  As it turns out i am a chicken and will end up paying someone $900 to lay the roof... oh well

Offline MarkAndDebbie

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Re: 20x30 stock, change roof pitch (collar ties)
« Reply #4 on: October 17, 2007, 01:05:41 PM »
I did a 10-12 on my shed. Sheathed it, but decided to let somebody else put the metal on. $550 materials and labor. Dimensions 12' ridge to eave - 20' along the ridge.

BTW - I'm not chicken ;)


 

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