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Felt damp under tiles

Simon Boyes

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40 minutes ago, Simon Boyes said:

Mark said non of the tiles were broken , although  he is fitting eaves trays . Can water leak through these tiles or is it condensation?

Thanks  simon

Imho. If there's trickles in one area then leaks. If the whole surface of roofing felt is damp condensation. Espically during warm days and cool nights....

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Hi @Simon Boyes Sorry about this.  


It looks like the overlap on each tile is short:


What pitch is the roof?

How far does each course of tile overlap the next course ( bottom of top tile onver the top of the next tile down. 


Is the building in exposed conditions?


Edited by Marvin
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I have no idea what the pitch is , by the look of it there must be 2 to 3 inch overlap . Surely building regulations would have been adhered  to . It isn't especially  exposed . 

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I think the minimum overlap is 75mm on a steep roof otherwise with a wind the water will travel up over the top tile, under the tile below.


If its like my roof 12 feet along to 5 feet up. It has to have a minimum of 4 inch overlap. 


If either of these are not right, or you are often exposed to driving rain, this will be the problem.


The solution will be to remove all the tiles, batten and roofing felt,replace the batten and felt spacing the batten tighter together which will mean having an extra row of batten and tiles, or 2, to make the overlap correct. You can re-use the tiles but if you break alot you can use old one one side and new on the other or all new ones. Be careful of the lead-in time from order to delivery of tiles, this can be months.


Good luck



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  • 4 weeks later...

Had the builder back and he confirmed  the tiles had a minimum of 75 mm overlap . I'm  putting it down to condensation  , the felt having rotted away at the bottom  obviously  was an issue , as any water trickling  down didn't  go into the guttering,  the fitting of eaves trays should  sort that problem .

Also had to have an air brick vent fitted in the upstairs bedroom because of mold caused by condensation  , caused by tennants  refusing to ventilate properly. 

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