What Lintel to fit above a 4 metre spread of Aluminium sliding doors?

[pmnb]

I want to replace old PVC single door and side windows by removing dwarf wall and installing a 4 metre run of aluminium sliding doors with new access door. Al this sits under a Polycarbonate roof in my sun room. Current lintel running above all glazing is just 4 x 2 timber. What lintel will I need to replace the old timber? Aluminium hopefully? Where can I obtain such a lintel? Will I need to build a supporting 'pillar' to support the new lintel at end of removed dwarf wall. The other end would sit on a standard 9" cavity block wall. Retired with time

 

[oldbutnotdead]

Do some research on your sliding doors first, look for ones where the weight of the doors is carried by the bottom track not the top. If you can settle on that type then your lintel will only be carrying roof load, might want to double the 4 x 2 for the increased span and allow for a 4 x 4 timber at the other end of the sliding door setup.
You'd need a very stiff lintel for tophung doors or bifolds....

 

[pmnb]

Many thanks, Bi-Fold is out for me, has to be sliding and I understand your thoughts on 'hung weight'. I had intended the weight to be carried by the bottom track. Will check this with manufacturers. The vertical support where I intend to split the current width of the dwarf wall is puzzling me (currently 22 feet long), I hoped to use some sort of UPVC clad steel or aluminium tube with capping to match the new install. I prefer not to use timber due to the exposed coastal location.