Ian_P Posted February 8, 2010 Report Share Posted February 8, 2010 Hi,With the purchase of a house I have inherited a low pitch roof. According to plans, the pitch is 10.5 degrees. The construction is a warm roof (ply on top layer), then monarfoil underlay, then battoned and counter battoned, then concrete interlocking tiles.The problem I have is that water gets behind the tiles during heavy rainfall. I recently had a leak on the eaves which I fixed but noticed that lots of the batons are rotting and the ply beneathe the monarfoil is wet - I assume through 'sweat'.I don't really want to fork out for a new flat roof as it's quite big (36m2). I am planning on re-battoning the roof and using a breathable underlay. My question is, will the breathable underlay be water resistance enough considering the low pitch of the roof? I was planning on battoning, then underlay, then counter battoning. Is this correct?Thanks Link to comment Share on other sites More sharing options...
verne Posted February 8, 2010 Report Share Posted February 8, 2010 i am no expert but 10.5 degrees sounds more suitable for sheet roofing material than tiles...i don't have any input for you about the correctness of your plans. i just wanted to remind you to use only treated timber and it would probably be good to give the plywood a coat or two also.low pitched roofs are often associated with lean-to type buildings. if this is so your water through the tiles might actually be finding ways past any flashing. it is also possible that moss has a good foothold and is beginning to lift the tiles a bit or is separating them...i feel the underlay should either be bonded to the ply in order to completely exclude water or should have a good gap for air circulation between the layers. i have no experience with breathable stuff - but my gore-tex jacket was a huge disappointment. it would cope with generated moisture while at rest or strolling but any effort would have me drenched and took hours to dry (it is a quality police issue jacket) so i am very suspicious about things claiming to be breathable...treating the tiles with a water repellant would probably help them to shed rain more quickly and efficiently thus reducing the chances of leaks and seepage and also reduce frost damage. Link to comment Share on other sites More sharing options...
builderbloke Posted October 31, 2011 Report Share Posted October 31, 2011 Try the new Permavent low pitch roofing web site. It seems to be very popular and the web site is very helpful. Link to comment Share on other sites More sharing options...
Recommended Posts