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ridge beam and rafter

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MountainDon:

Garrett In Tahoe:
Yes the above picture is the preferred way to frame at your ridge beam. The lapping of the rafters gives a good lateral tie and the additional length (vs a plumb cut) keeps the end of the rafter from splitting at the seat cut. Solid block between the rafters on top of the ridge, notch them for ventilation so you get air flow from your eves to your ridge vent, which prevents condensation.

Normally a rige board is used where you have a self supporting roof and the opposing forces from each side are holding it up. Usually only designed on shorter spans with light roof loads. But if it is designed as a bearing ridge with a beam then you can still butt the ridge with a plumb cut rafter, but normally you're also required to have joist hangers on the rafters.

Garrett In Tahoe:
Oh yeah, I forgot the most important reason for a ridge beam in a cathedral ceiling. You have no ceiling joists to keep the walls from spreading from the weight of the roof. The joists act as ties to keep the roof from coming down, and the walls from spreading, creating a truss effect.

PEG688:
Ridge BEAMS and ridge BOARDS  are two different critters.

 A Ridge Beam is a bigger timber , generally solidly supported to bearing (foundation / ground ) at points (either end ) .

 A Ridge board is part of a roof system "that  one  part helps/ augments  another"  to create a greater stronger "whole" in the system.

  Ridge beam , as Mtn.D has shown can be placed below or partly  below the rafters ,


 

  rafters "birds mouthed " over the top of the exposed BEAM , beam solidly supported at both ends so not sagging / wall spreading can take place.


 Here's a ridge board , generally a 2x12 or so , although in the old days , 30 years ago and more a 1x was or could be used,  here's a ridge board 1x6 , 60 year old house , my own , a hip roof 2x6 rafter , some what over spanned in lenght , we'd never be able to build this house this way today , yet it's 60 years old and survived at least 3 earthquakes in this area. No "large" quakes just normal ones , no lahars either for that matter heh 



 



 Today it would look like this where rafters meet ridge should look much like this , as in no big gaps between the meeting members,

 



 Ridge board , dormer rafters , main roof rafters , and a strong back to "help" the ceiling joist ( that also in the dormers act as collar ties in many ways ,


 
 



  Basic rafter , collar tie , ceiling joist over view,



  


 So terms and words mean specific things, mixing words and terms leads to confusion. 

davidj:
I guess "fake post, plank and beam" was the term that I was looking for.  Using the real ridge beam, fake "roof beams" (diy glulam from 2x4s or just some 1x made into a box) and fake roof decking (using 1x tongue and groove, rather than 2x or 3x).  Real post, plank and beam would obviously be even better, but I'm guessing a fair bit more expensive and time consuming.

Or maybe I should just copy my 1920's bungalow - 1x6 ridge board, 2x4 rafters spanning 20' (with the occasional purlin about 2/5 of the way along).  Or would that fall slightly short of modern code?

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