Tiled roof (water going the wrong way )

From: Adam Randall


Thought I would fix a couple of leaks in the roof before starting the renovation in the games room, it was at this stage I found I owned a second swimming pool.
I have spent the last 2 days cleaning all the crap that gets stuck in between the tiles (very leafy suburb), as well as pulling alot of the rat poo, water logged insulation out, along with some very interesting skeletal remains (talon has its disadvantages).
The roof is a exposed beam and the slats the tiles sit on hold water on the high side, before the water gradually drains out through the ceiling and beam ends. I am really hoping the major clean up I have undertaken will stop the water entering the roof. The tiles themselves are in tip top shape, and after a bit of experimenting I seem to have found where the water is getting in. The tiles overlap by about 10cms, and when I pour water down from the top of the roof the water actually goes where it is supposed to (in the gutter) except the water actually goes upwards, yes you heard right, the water travels that 10cm in an upwards direction, completely breaking the laws of physics, and dribbling down the inside edge of the tile and resting gently against the nearest wooden batten where the rotting process begins. If anyone knows what is causing this please help. For information that part of the roof is at about a 20 degree incline.
Regards Adam
 
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Reply: 1
From: Eric Kendall


Hello Adam, an interesting phenomena commonly known as capillary action. This was a common problem a number of years ago with cheap imported corrugated colour bond roofing that was installed on a low pitch. The overlapping corrugations fitted together with virtually no air gap. This enabled capillary action to take place and thus the water to climb between the corrugations and drip onto the ceiling below.
One solution in your case would be to make sure there is an air gap or relief at the top end of the matching tiles.
Type in "capillary action" to a search engine for a full explanation……………….
 
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Reply: 1.1
From: Stirling Reid



For tiles on a low slope it is recommended that you lay sarking over the rafters before putting on the tiles. Sarking is a silver and mastic material that comes on rolls. This forms a waterproof membrane and keeps water off the timber work.

Stirling
 
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Reply: 2
From: Adam Randall


Thanks for the replies, I will have to do some research on this subject, at present I cannot afford to put sarking over the battons, however this seems like the most reasonable action, will black plastic be just as effective.
Regards Adam
 
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