How to build up manhole (internal)?

[oly]

Conventional external rectangular manhole will become internal. I have a nice new locking cover (58mm deep) which will be fitted about 150 mm higher than existing to be level with DPC/ top of screed.

Should I use sharp sand mortar and engineering bricks and should I use PVA to bond to old brickwork?

1 course will leave the height short by about 40mm so should I just use extra thick layers of mortar, or should I cut some slithers of brick?

Should DPM be set into the brick work?

Cheers for any advice.

 

[kazuya]

not built a brick manhole in many years but if I remember rightly, use normal sand but a strong mix, no more than 4-1 and engineering bricks, also I'm pretty sure we used to stagger the joints as well, defiantly the perps anyway.
don't use a thick bed, slithers would be better, but engineering bricks will be hard to cut, what if you lay a brick on edge like they do the top of a wall, is that any closer to the right hight?

 

[ree]

OP, instead of attempting to cut bricks, why not build up a thick rim of semi dry sand and cement at 3:1 and set the cover frame into the mix when you are certain of the FFL. Some covers are adjustable in height.

Dont use any PVA, no DPM necessary.

All the above depend on how the new floor is going down, and the accuracy of your dimensions.

 

[noseall]

Don't set the lid and frame until you are ready to screed the floor.

Rather, set the masonry so that it finishes to full bricks i.e. without any slithers. Just plonk the lid or a bit of ply over the hole for now, then set the lid proper when you surround the IC with the screed.

Don't forget to lap your DPM onto the IC masonry.

 

[oly]

Don't set the lid and frame until you are ready to screed the floor.

Rather, set the masonry so that it finishes to full bricks i.e. without any slithers. Just plonk the lid or a bit of ply over the hole for now, then set the lid proper when you surround the IC with the screed.

Don't forget to lap your DPM onto the IC masonry.

Ok thanks Noseall, that makes a lot of sense.

I guess the IC plastic frame make a sort of DPC but if I lap the DPM under that I'm not sure they'll be much mortar actually in contact with the frame, wonder if I could just stick the DPM to the side of the masonry with bitumen or something?

 

[noseall]

I guess the IC plastic frame make a sort of DPC but if I lap the DPM under that I'm not sure they'll be much mortar actually in contact with the frame, wonder if I could just stick the DPM to the side of the masonry with bitumen or something?

Sorry thought it was a brick chamber!

Yeah just lap the poly up the sides.