Gable vs. shed-style roof

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neb

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#258639 14-Oct-2019 14:11

As part of the redo of the Casa de Cowboy, we're extending two of the rooms so they stick out from the main part of the house, in effect turning the longish rectangle into more of an F-shape, with the prongs on the F being the extended parts. To roof over these parts there are two (obvious) options, do it as a cross gable or run a shed-style roof, i.e. make the portions of the roof over the prongs a shallower slope so they can run out further than the steeper-sloping main roof.

Does anyone have any thoughts about the pros/cons of either? Since the roof will be long-run steel, the shed roof will be much easier to deal with, the cross gable will have lots of finicky corners and joins with potential for water trapping/rust (we're on the coast). However, the shed-style roof may look kinda ugly... we're undecided at the moment. Are there any downsides apart from visual to doing a shed-style roof? Are we exaggerating the potential problems with the cross gable?

richms

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#2336817 14-Oct-2019 14:25

Do you often look at your roof to worry about how ugly it looks? More corners, more flashing, more places to leak, also gables would have inside corners needing the trough in it, and IME that is where things go wrong with wind and lots of rain.

Richard rich.ms

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#2336829 14-Oct-2019 15:24

What would the pitch be on the extensions. We have a bedroom and porch that share a single plane roof that is marginal for corrugated roofing. When it was replaced I asked about repitching as we had done for the main roof but the builder assured us that changing to 5 rib would do. There is no problem with rain being blown under side laps but the deeper profile stops the wind from blowing leaves off the roof. This roof needs periodic hosing to clear the debris.

mattwnz

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#2336845 14-Oct-2019 15:34

What is the current pitch on the current roof? Hipped, gales, internal valleys etc are all fairly common on basic pitched roofs in NZ. If you are going to do it like a lean to with a shed type roof, then it maybe difficult in terms of ceiling heights in the room, and being able to get it under the roof. But a 3D sketch showing how you want to do it may help. I would suggest looking at the metal roofing code of practice website and document they have online, as it goes through a lot of details with designing for metal roofs. .

wellygary

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#2336846 14-Oct-2019 15:36

Shed Style will be a whole lot cheaper and easier, ( assuming you have enough fall height for the roof)

- But it will possibly have ceiling height issues, along with restrictions on access to the roof space in the extension for later insulation upgrades, wire running etc,

mattwnz

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#2336847 14-Oct-2019 15:44

wellygary:

Shed Style will be a whole lot cheaper and easier, ( assuming you have enough fall height for the roof)

- But it will possibly have ceiling height issues, along with restrictions on access to the roof space in the extension for later insulation upgrades, wire running etc,

If it is well insulated to begin with, then that shouldn't be too much of an issue. Except if the electrician decides to create big holes in the insulation above downlights to get wires through.

neb

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#2336848 14-Oct-2019 15:54

The extensions are only about 1.5m so the slope will be only slightly shallower than the existing roof. Roof space isn't a problem, we're raising it slightly to allow for the addition of eaves to the house (I did mention it's the Casa de Cowboy, right?) so the additional height will make up for the slightly longer roof. It's mainly finding out whether there's any hidden gotchas in the shed-style roof. Certainly from a practicality point of view it seems like the better option.

In the meantime SWMBO has weighed in and indicated she prefers the shed-style roof to a cross gable, so it's starting to look like a no-brainer.

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Paul1977

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#2336857 14-Oct-2019 16:28

What is the existing roof style? Standard A-frame with a gable at each end, gable at one end and hip at the other, hip at both ends?

What is the pitch of the existing roof?

Paul1977

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#2336859 14-Oct-2019 16:30

neb: The extensions are only about 1.5m so the slope will be only slightly shallower than the existing roof

Are you planning on starting shed-style roof from the apex of the existing roof, or lower down?

neb

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#2336865 14-Oct-2019 16:37

Paul1977:
What is the existing roof style? Standard A-frame with a gable at each end, gable at one end and hip at the other, hip at both ends?

What is the pitch of the existing roof?

Standard 1970s A-frame with gable, nothing fancy.

Unfortunately I don't know what the pitch is, I'd estimate about 30-35 degrees.

neb

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#2336867 14-Oct-2019 16:39

Paul1977:
neb: The extensions are only about 1.5m so the slope will be only slightly shallower than the existing roof

Are you planning on starting shed-style roof from the apex of the existing roof, or lower down?

Ah, excellent point, starting lower down would be better visually. From memory the minimum pitch is 8 degrees for corrugate and even less for other types of long-run, so that sholdn't be much of an issue with the main roof at 30-35 degrees.

mattwnz

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#2336887 14-Oct-2019 17:01

I think appearance is a major issue, especially when it comes to reselling. Bad roof lines can turn people off a house, and it can be false economy just to go for the cheapest option. Although a shed style/ skillion roof can often look better and more modern depending on the design and how it is implemented. But sometimes it isn't.

I think you can go down as low as 3 degrees with some profiles, but they will often be slightly more expensive them normal corrugated steel. Then you can also go the membrane option, which is a coastal environment, at least it won't rust.

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Paul1977

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#2337211 15-Oct-2019 09:49

mattwnz:

I think appearance is a major issue, especially when it comes to reselling. Bad roof lines can turn people off a house, and it can be false economy just to go for the cheapest option. Although a shed style/ skillion roof can often look better and more modern depending on the design and how it is implemented. But sometimes it isn't.

I agree.

I like skillion roofs, but I'm personally not convinced it would look "right" attached to a standard A-frame. I prefer having either one or the other, rather than mixing two very different styles. My vote would be on cross gable from a purely aesthetic perspective.

That said, I have no idea how much more it would cost.