Posted on January 16, 2015 in FAQs
All dimensions should be measured to the OVERALL EXTERNAL UPSTAND including weathering, pay particular attention to the corners where your roof finish may have had extra layers applied. The roof light fits over the edge of the upstand/kerb and is manufactured with a tolerance to allow for small variations but care should be taken when taking measurements.
E.g. if you order a 2000mm x 1000mm roof light, this refers to the external dimensions of the kerb including weathering and NOT the actual product.
If you are in any doubt you can view further details on drawing ref S0009 or give us a call.