Lintel advise please

[jackthelad]

I have a solid brick single storey extension to an old terraced house, which has a very short window in it. I would like to fit a taller window for more light better view etc. There is a 75mm wall plate on top of the masonry with the roof timber fixed directly to it. I intent to take out brickwork up to the wall plate and install a lintel directly under the wall plate.
My questions are.....
Can I use a concrete lintel, I have been advised that concrete lintels should only be used if a minimum of 4 courses of masonry is to be laid over the
lintel ?
Can I use a timber lintel ? (The existing lintels are timber)

I have read up on lintel fitting steel or concrete, I understand about packing them up, using steel shims or slate. This may be a dumb question but, steel shims, where can you get them? Also is the slate used pieces of roofing slate or something else?

Thanks in advance for any help and advice.

 

[catlad]

how wide is the window and what is on the roof.

 

[jackthelad]

Hi sorry for the slow reply Catlad. I have been flat out on the afore mentioned house, with no internet access.

The window opening is 1760 mm wide.
Tho roof is concrete tiles.

Thank Tony

 

[themiddleagedun]

I'd use a 6x4 concrete lintel.

 

[tony1851]

For a 1760 span supporting just a roof, personally I'd just use a 6x4 timber lintel (or two 6x2s screwed together). Light, easy to manouver in, and easy to nail plasterboard to. Roof loads are not very high.