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Roof pitch calculations

Single storey extension, used Architect for main plans & structural engineers for beam calcs etc but builder has pitched roof so that the first membrane layer fits direct under upstairs window leaving no gap for flashing or tiles. Cannot see any pitch calcs on architect/structural engineer plans - is it up to builder to correctly calculate pitch, if so is this normal?

2 Answers from MyBuilder Extension Builders

Your builder should be using the drawings to calculate the pitch. Your architect will have drawn it on the plans and it will be quite straight forward for your builder to use a protractor and construct the roof accordingly. If there isn't a gap large enough for the tiles and flashing to go under the window either the architect has drawn it wrong or the builder has built it wrong. A good builder would have seen the problem prior to constructing the roof. Hope this helps


Answered 22nd Jul 2017

The pitch should be stated on the architects drawing and then checked on site. Whether there is or not the builder should have allowed for upstand and cover flashing under the window during construction. Checking the pitch with an electronic angle finder to make sure the pitch is within the limit of the tiles being used. It is sometimes necessary to alter the details on an architects drawing during the build for practical reasons. However all variations should be explained to the client and approval given before being implemented.


Answered 29th Jul 2017

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