How much should a concrete lintel be over the size of the patio doors?

Once you have put appropriate acro props etc in place. (i use counter levered strongboys) The mounting platform should consist of concrete padstones with the following dimensions.400mm long x 100mm wide or as wide as the wall x 300mm deep. Actual lintel to be aprox 400mm over each side. Louis.

get a structural engineer to do calcs for you it varies from property to property depending on load bearing ect

150mm longer either side of opening

min 18" bigger than opening

Hi your lintel will need to minimum 1800 mm but it needs to be steel not concrete,you don't say what type of property you live but assuming its a house of modern construction i,e cavity wall if it has a 70 to 75 mm cavity use a birtley cb70 hd lintel. This work should be done by an experienced builder as any opening over 1 metre wont self support and will need supported with acrowes regards john

2100mm Concrete Lintel will be more than enough