How to render inside a manhole cover

[Vicario]

Just finished investigating a blocked drain. When I took off the manhole cover I saw that bits of the lining had broken and fallen into the drain - one large bit was partly blocking the outlet, hence the problem. Anyway, all removed and running freely. But the wall of the manhole is cracked and peeling. In some places the brickwork is visible so I'd like to chip off any loose bits and re-render. What is the best type of render for this kind of job? It's on my property so not the water company's responsibility.

 

[Alastairreid]

I would'nt bother rendering it! it will eventually come back off.
Remove the rendering thats left and point up the brickwork.

 

[roy c]

Sometimes when a manhole is built and the drain channel is at the bottom there is a need to "haunch"or bench the sides up to help the water flow away smoothly.A section of this could of been what has broken away and blocked your drain. If you are going to bench it back up you could use rapid drying mortar that you can buy in small bags, this helps if the drain is "active " and you can only stop the flow of water for a short while. If you can stop the flow for a long time (time to let your mortar to go off) then I would use a 3 or 4-1 sand and cement mix at floor laying consistency (Holds together when you squeeze it in your hand)as this will go very hard as there will be minimum water in the mix. Pack it in and use a float to shape it and sponge over it after. Or if as alastairreid said the mortar has come out of the brickwork just re-point it.

 

[Vicario]

No, it's definitely come from the sides (3 of the 4) and quite high up. There were about 10 smallish flat bits and then the big one (about 10cm by 12) which was lying up against the outlet. I can see the bare brickwork where this came off - I suspect frost damage over the winter as I flushed it in the autumn and it looked fine. The pointing looks sound so I'll leave it until the weather warms up and then chip off any loose stuff and take your advice. The benching is intact. Lovely job for a Sunday morning, as you can imagine; it wasn't blocked completely, thankfully!

 

[gregers]

quickly

 

[shapnacker]

roy c - I have a similar issue. Should I render with sharp or builders sand?

 

[roy c]

Sharp sand mucka,,

 

[shapnacker]

Any waterproofer required?

 

[roy c]

No problem putting some w/proofer in the "render mix" but if you are haunching or "benching" then there is no need as the dryish mix (floor screed mix) will go off rock hard because there is minimun water in it....(Just mixed up so you can squeeze it in your hand and it just holds together and doesn't fall apart) that is the way you gauge when your screed mix is correct....