Making a sagging roof ... Karl. A

Karl.A

kebmo said:

i've wanted to scratch build a small abandoned structure with a sagging roof for a long time but was hesitant because wasn't able to figure out how to sag the roof.

I'm sure this is covered in one of Brett's manuals, probably Main Street as that is the roof I was copying this time.
I used the following technique that I've used previously, and now on my upscale build to get the result to match Brett's roof.

Here's a quick SBS summary I just made for the steps to make a sagging roof.

Fold your roof card in half



Once folded draw a shallow curve on the ridgeline, make it shallow as you'll be surprised how much it sags.
It's much easier to make it a bit bigger if you need to later.



Cut out the curve, leave the ends attached so the roof is in one piece.



Open out the card and you should have this result.



Fold the card in half again and add a couple of pieces of tape to hold the ridge together.



Open out the roof and you will have a sagging roof.
If it's not sagged enough for your liking remove the tape and cut a little more away, retape and re-assess until you get it how you like it.



Paint it black and continue.



An old build with the Job done,

brownbr

This is a good one Karl. This is my plan B if I go with the full interior of the tool shed and plan A if I go with closed doors.

I'll want to see the rafters if I go with open doors so I'm toying around with a couple of ideas to make that happen.

Karl.A

Thanks Bryan,

Use the sagged roof as your base Bryan, run a line of glue or epoxy along the inside of the ridge and place it on the structure so that it dries rigid at the angle that you want it.

Once dry, remove the roof from the building, flip it over and add the rafters to the inside of the subroof.
I did this once on a test build and it worked out great, the build never went any further than that though.
You can use straight edge clippers to notch out the rafters for the walls once the rafters are dry and secured to the subroof if you want the roof to 'sit down'.

Hope that helps, or gives you some ideas.

SteveF

Another great tutorial Karl. I like the idea of a sagged roof and it couldn't be any easier the way you've described it. I would have never thought that you could add rafters to a sagging roof but again your description of setting the angle with epoxy makes perfect sense.
Just to clarify, you are just installing rafters of different length to follow the sag but I'm guessing you are not installing anything along the ridge because obviously you can't follow the curve of the sag with a straight board. The epoxy is holding the angle and there is no reason for anything more than the rafters. Correct?

Karl.A

Correct Steve,

If the roof is on, either permanent or removable (as a whole), when you look through the doors, especially on something as small as the tool shed you cant see up to the ridge anyway, so no need to worry too much about it, what you want to see and I think what Bryan is aiming to show is to make the mid and lower section of the rafters visible which gives an incredible effect of realism, esp when lit.
The top third or quarter of the roof interior can be painted black and faded down, this makes it 'invisible' but still gives an awesome effect and view to anyone looking in at it through the doors.

SteveF

Thanks for the clarification and the ongoing education! I'm looking forward to trying this on a future build. Great point about seeing just the lower portion of the rafters when looking through a door. I'm thinking one could also add ceiling joists across the inner portion of the lower rafters which will aid in holding the shape of the roof and help to make it removable for future access. Definitely have to add that to the list of future projects.

Karl.A

Thanks Steve,
sometimes we have to 'cheat' a little and just create the 'illusion'...

Turning the rafters into 'A' frames is indeed a great way to go if the roof is going to be removeable, that absolutely keeps everything solid after you have all the angles set. I've definitely used that method several times on builds, and, it has always worked well.

vietnamseabee

Oh man….now you tell me….back in my prior life I was a project manager for an architect that did a lot of work at Walt Disney World,,,,, I had a bus shelter project that had a themed sagging roof and a lot of engineering and thought went into it…..if only I had used Karl’s methodology. ;-))
Terry

kebmo

thanks karl. once again you've educated me.

Jeroen

That looks awesome! Perhaps a stupid question but is this a kit or did you scratchbuild it entirely? In any case; stellar work!

Karl.A

Thanks Terry, Kev and Jeroen.

Jeroen its an old full O scale scratch build of mine copying Brett's incredible HO scale Mainstreet Kit.

Here's a link to my build here on the forum if you want to look. Feel free to comment in that thread if you have any questions.

http://www.craftsmankituniversity.com/vanforum/index.php?p=/discussion/1268/the-main-street-warehouse-206-in-o-scale-karl-a

Enjoy !

glandesjr

Karl:
What a great idea. Thanks for this tutorial. I just added it to my book of Karl Tutorials.

Karl.A

Thanks George, hope it helps.

Jeroen

Awesome Karl, many thanks!

Karl.A

Anytime.