If its an outside box, you'd *possibly* be better with at least of a bit of a slope to stop standing water.  Get as much off the box as possible and hopefully less will get inside!

Yup.  The actual Met box is bad enough, but TARDISes...  If I'd known how steep an Met Box roof is before building mine, I'd have used those dimensions for a starting point instead of the 1963 prop.  That said, when I did the build (before I got here) I considered finding a shower stall base and using that for my roof.  Barring that, if you're set on the chopped Barachaki, consider fiberglass. People complain about the smell, but as someone who built a lot of models as a kid, it was a reminder of childhood and airplane glue.  And for the most part go with fiber cloth instead of non-oriented fiber. 

The latter is more flexible because it is fairly weak and shapeless, but as hard to work with as stuffing a cat in a sack.  You've got to get the resin on in 1 shot.  Because if you go back, fiber strands start coming up.  The more you work it, the messier it gets.  On the other hand actual woven fiber strands don't handle corners as nicely, but they're so much easier to work with.

The guys are so right.

If it's going to be an outside box then a flat roof will be a potential water trap which will lead to rot double quick.

Outside boxes need a lot of work to keep them in good nick.

If you don't want to go the fibreglass route, this is what I did on my plywood roof...


1st coat:  Cuprinol waterproof wood stain.
2nd coat:  Undercoat.
3rd Coat:  Bitumen roof seal.
4th coat: Exterior gloss (2 coats)

That should do the trick, but - & it's a big but- the most important thing is constant maintenance- keeping a constant eye on it & addressing any minor issues quickly before they grow, then once a year give the whole thing a good overhaul & full repaint.

It seems like lots of work, but it's no more than keeping any wooden exterior shed in good nick.

Good luck!

Russell

Quote from: Thefirsttee1960 on Sep 21, 2020, 08:36 pmMy grandson lives Patrick troughton, so I've decided to go with a flat roof.

A little different to the norm.
It will be interesting to see how it turns out.

The 1966 refit of the original prop had the original roof still.  It has a pitch to it. The height of the pitch is about the same as the height of the roof below the pitch, as you can see in this photo from The Abominable Snowmen.  As as others have said, with this being outdoors, an pitched roof will help rain run off instead of pooling and causing the roof to rot quicker.
Bill Rudloff

Quote from: Thefirsttee1960 on Sep 21, 2020, 08:36 pmMy grandson lives Patrick troughton

He's got good taste your Grandson