lintel replacement

[vansbest]

Hi, I previously posted regarding spalled lintels in a No Fines concrete house. I engaged a structural engineer regarding replacement of these. However I would appreciate your advice as to the best way of building the replacements in. The SE has specified a replacement which is 210 in height as opposed to 250 height of the original. He has specified that the top of the lintels (3m and 2.5m long) be packed with slate and a 'dry' mortar mix. I reckon a better/ easier option would be to lay a mortar bed along the full length of the top of the lintel, jack this up tight to the No Fines concrete and then pack the bearing surfaces (200mm) with slate and the 'dry' concrete mix.
Any thoughts/ opinions, as usual greatly appreciated
thanks

 

[tony1851]

vansbest; I think I remember your post as I was doing a design for an extension to a No-Fines house at the time - nightmare!
Has the SE specified reinforced concrete lintels? If so, why not steel - might be a bit lighter than p/c lintels.

If you can manage to jack the beam up with mortar on top, I would think that would give it a more even bearing than packing with bits of slate.
What you have to watch also is the bearing at the ends. 200mm I would say is a minimum; that stuff is like crunchy bar and not good for taking the point load at a beam bearing. Make sure it is well- and evenly packed underneath to prevent localised crushing.

 

[vansbest]

thanks for the prompt response. the SE has spec'd a PC lintel 215 x100 for the inside, a 150 x 150 hot dipped galvanised RSA with 3 courses of facing brick on top, weep vents every 450 on first course. DPC from top of internal lintel running over RSA and under first course. If you were agreeable I could pm you the drawings. It has taken him 6 weeks since first site visit, cost me a fortune, and still not resolved