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KinAlberta
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# Posted: 25 Apr 2018 01:03pm - Edited by: KinAlberta
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A new hairbrained idea here.  I’m still running different ideas though my head to create a much nicer or more interesting interior on our 24’x24’ cabin. Summer use only. I’d love to remove the flat ceiling and have a open beam or cathedral ceiling in it.
So now I’m wondering if I couldn’t reinforce the gable ends then put at the 8’ mark, at the centre/ridge and at the 16’ mark, three 24’ long beams - on top of the roof.
First strip off the sheathing to the peak on both sides, then put the beams on top of the rafters parallel with the ridge on either side of the ridge and the third beam ridge down the length of the centre ridge. Then strap / attach the rafters to the beam and then roof above the top mounted beams by glassing the now open area. I’d have two sets of rafters and two ridgeboards. Once this was done (with proper support at either gable end), I’d then remove the ceiling joists, collar ties etc.
Some detail: Looking at it the cabin from the front, it’s all open space except for two 8’x8’ bedrooms filling the right side-back 1/3 of the cabin. (An 8’wide x16’ deep walled in space with the two bedrooms.) Gable roof with ridge running parallel with the front.
So far ive just thought of removing the ceiling in this cabin by putting in new support beams (over a 16’ wise living room/ kitchen span and then supported over the interior wall but continuing the full 24’. Thus three new beams would be put in running parallel to the ridge. At 8’, 12’(Centre) and 16’.
Maybe this is easier - then just have a 3’-4’ or so glass roof.
http://www.marmol-radziner.com/experimental-ranch-architecture/
http://www.marmol-radziner.com/wp-content/uploads/2016/04/experimental-ranch-1-1920x1 541.jpg
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ICC
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# Posted: 25 Apr 2018 01:27pm - Edited by: ICC
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edited
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95XL883
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# Posted: 25 Apr 2018 01:43pm
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I think I understand what you are asking. Basically, you want to open up the interior by removing ceiling and all rafter ties. Rather than going with a ridge beam, you're wondering if you can support the rafters with beams. Your example photo shows the beams under the rafters. If I understand what you are asking is can you have the beams above the roof. Basically you are trying to have your interior ceiling being a very open vault.
Sorry, I don't know the specific answer to your question but I suspect the answer is no because the purpose of a ridge beam and rafter ties is to keep the roof from pushing the walls out.
I guess another way of asking your question is can two beams, neither of which is a ridge beam, adequately support a roof and prevent the walls from being pushed out.
Sorry, I'm not more help but I find your question very interesting. Not sure that I would try but it is a cool idea and a cool look.
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ICC
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# Posted: 25 Apr 2018 07:13pm - Edited by: ICC
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You do seem to understand that one of the tasks the ceiling joists / rafter ties accomplish is to prevent the rafters from pushing out the tops of the side walls. Using a ridge-BEAM in the conventional method splits the load to 50% on the ridge-BEAM and 25% on each side wall and removes the necessity to have rafter ties.
You mention reinforcing the gable ends to carry the loads. To carry the loads to what type of foundation? If you have the prototypical pier and beam foundation, forget the idea. Even the normal house full perimeter poured concrete foundation may not be up to the point loads those gable columns will produce.
You mention adding 2 extra beams in addition the the ridge. . I’d have two sets of rafters and two ridgeboards. I really don’t follow that thought and hate guessing. My guess is the 2 extra beams would be to share the roof load. Okay, but the load still needs to be spread out onto the ground. And that gets into the realm of engineering calculations.
More data is needed. Pictures, drawings, etc. would be nice to be able to not have any misunderstanding. What’s the snow load? What the soil load carrying ability and, as mentioned already, what is the present foundation? Can there be intermediate columns down to foundation anywhere in mid span of those beams?
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KinAlberta
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# Posted: 25 Apr 2018 09:09pm - Edited by: KinAlberta
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Actually moving the beams above the roof would allow for a second set of raised rafters from the beams to a second higher peak and the addition of glass or lexan.
I’ll try to find an example and post.
Snow load: code here is minimum 22 pounds per square foot.
The beams: one ridge beam or ridge board and two purlins (beams running parallel to the ridge)
Roof style: “monitor roofâ€
Glass: skylight not cupola windows
Spans: no greater than existing spans
This is a bit like what I’m thinking of:
https://en.m.wikipedia.org/wiki/Skylight#/media/File%3AHK_Central_Star_Ferry_Pier_7_S hop_L_Restaurant_WaterMark_a2.jpg
I’ll be back. More searching to do
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Cowracer
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# Posted: 26 Apr 2018 09:27am - Edited by: Cowracer
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Personal taste and all that, but to me it looks like a Holiday Inn lobby that needs updating..
http://www.marmol-radziner.com/wp-content/uploads/2016/04/experimental-ranch-1-1920x1 541.jpg
Tim
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ICC
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# Posted: 26 Apr 2018 10:07am
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Looks and whether or not we like it is still a moot point, I think. What is the foundation? Until it is known if the present foundation is adequate to carry the new load paths why waste time figuring out how the roof might be done. building renovations such as this must include a hard look at the foundation.
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