Concrete lintel over sewer pipe gap

[Flathead]

Hello there, I'm in the progress of building single storey extension, cavity wall - 2.46m high, Celcon blocks on both sides of cavity. I've the foundation done with a cut out for the sewer pipe parallel to the house wall. I wonder what would be the right type of the lintel for the 600 mm opening. I know it has to be minimum 900mm in length but struggle to answer my self what type of the lintel would be sufficient, 140x100 or 215x100 prestressed one? Local BCO didn't help a lot as he said it should be 150x100 precast one. No one stocks them near my place. Any thoughts here guys? I don't want to go expensive way with the SE yet, as it would probably delay the next week schedule.

 

[themiddleagedun]

Why is the opening that wide just for a drain? Anyway, a 900x100x65mm lintel is definitely suitable & will be in stock at any builders merchants.

 

[^woody^]

Concrete!

As wide as the pipe, plus 50mm gap each side plus 100mm bearing each side - so pipe plus 300mm

 

[oldbutnotdead]

If BCO wants minimum 150 x 100 then you want that or better so 215 x 100 will be fine.Yes they'll be more expensive than 150 but if they avoid SE calcs then you'll still be saving

 

[Flathead]

Thank you for the advice. The reason for the wide gap is that pipe was sitting on quite thick piles of mortar/screed mixed with ballast (a bit pinkish in colour) on one side of the foundation and fully covered by that on the other side. I assume it had a support purpose at the time of built. So we add a bit of gap on both sides of the pipe to get more of the pebble to more less surround it the best we can. I measured the gaps again - the widest point is 550 so I will stick to 900x100x65mm lintel. Still I don't understand the "precast" suggestion from the BCO.

 

[Flathead]

Hmmm, 215x100? Looks like I have to call the BC again. At the same time the load resistance of the precast 150x100 and prestressed 140x100 should be more less the same if not in favour of the prestressed one.

 

[oldbutnotdead]

BCOs seem to have their own little pet theories (sometimes exceeding the requirements). With ours up here I've found if you cater to their desires (where it isn't economically ruinous) they are much more accommodating on areas where strict compliance with ADs is more difficult (old houses can be a pain at times)