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Posted: Wed Jun 21, 2017 5:48 pm
by mosquat
Hi all,
I need to lower the existing cover slightly, and then I can hopefully fit a square to round recess cover.
however has anyone got any advice on what I can do with the current riser (pictured)? It seems to be made of metal so not sure if it can be cut or maybe there are "rings" I can remove once the existing cover is removed?
hoping someone has seen one of these before and can point me in the right direction:
Cheers for any help
Carl
Posted: Wed Jun 21, 2017 6:15 pm
by digerjones
I would say they are plastic risers, if so quiet straight forward.
Posted: Wed Jun 21, 2017 6:44 pm
by seanandruby
The cover is metal about 30ish ml thick. The risers will be plastic, about 300ish in height. I presume this will be in a driveway? Cut the existing to required height allowing an upstand to stop concrete falling in i c. The top 150 will need to be a concrete plinth. Wrap around the fins with something so that no concrete actually touches the fins , that way the i c won't be load bearing.
Posted: Wed Jun 21, 2017 7:21 pm
by mosquat
Thanks for the advice, I will double check them again but they feel metallic, I hope you're right of course.
Sean - great advice. Are the fins the technical term for the riser rings? Sorry for the dumb Q
Posted: Thu Jun 22, 2017 6:54 am
by seanandruby
If they are metal then you will need to cut with a petrol saw such as sthill saw and metal cutting blade. No a riser is correct term. As you can see it's smooth on the inside riser but on the outside there are 'fins'. If you sctatch the inside with a nail, screwdriver, it will give you an idea of material used. Never come across a metal riser before.
Posted: Thu Jun 22, 2017 1:01 pm
by Tony McC
They are plastic risers/raising sections, so it's nowt more complicated than breaking out the concrete haunch around the existing circular frame and then using a nangle grinder to slice through the riser from inside the chamber.
Best to dig out around the raising piece *before* you cut it, to a depth roughly 50-100mm below where you intend to cut it, so that the backfill material doesn't fall into the chamber whgen you remove the unwanted section.
Posted: Thu Jun 22, 2017 4:59 pm
by mosquat
Cheers everyone, consensus this end is plastic too, glad we had this discussion all the same
Posted: Sat Jun 24, 2017 8:52 am
by jwill
So these lids should always be bedded off the subbase rather than connect to risers if in a driveway?
Posted: Sat Jun 24, 2017 9:40 am
by seanandruby
All I Cs inspection chambers, covers, lids etc: have different loadings, surround specs' etc: in a drive there must be 150 ml deep concrete plinth surround.
Posted: Sat Jun 24, 2017 12:53 pm
by Tony McC
The circular covers for circular ICs bed directly onto the raising rings but, when used in a pavement subject to vehicular traffic, they are usually set onto a concrete bed which surrounds the raising ring, to reduce the vertical loading on the IC.
Posted: Sat Jun 24, 2017 1:33 pm
by jwill
Yes understand. Still connected but bedded/haunched to spread load
Posted: Sat Jun 24, 2017 3:46 pm
by seanandruby
Bearing in mind the vertical load is still imposed if concreting directly against the ribs/fins. An external shutter is needed around the riser to avoid concreting the ribs/fins with concrete collar. The collar/plinth needs to be wide enough to carry the frame.
Posted: Mon Jul 10, 2017 9:22 pm
by Forestboy1978
I did this exact thing only last month to 3 drains that were creating tripping hazards. Marked a line where I wanted to cut, drilled a hole and then cut through them like swiss cheese with a jigsaw. Billed an architectural company 270 for that and re haunching the lid supports. Took me 2 hours including travel time. Was chuffed as pie.