Inspection chamber - single or double skin brickwork?

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Peter500

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I'm building a brick inspection chamber. I've read some things online that say that they should have a double skin with engineering bricks. I know many are only single skin, like my existing inspection chamber that is built with normal (non-engineering) bricks.

Should it be double skin or not? It not actually carrying any water, it will just have a backflow valve on 110mm that I will need to inspect/clean periodically. The size is 890x665 and it's 1m deep.
 
^woody^ said:
One brick thick, English or Water bond, class b bricks in 3:1 mortar.
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I was going to use M6 mortar like I have for other DPC brickwork. Does it really need to be that strong?

I'm not sure what water bond is. I want to make sure it isn't water tight as I want water to drain out of it (slowly). It's below the water table level so water will almost certainly get in there.
 
Peter500 said:
I was going to use M6 mortar like I have for other DPC brickwork. Does it really need to be that strong?

I'm not sure what water bond is. I want to make sure it isn't water tight as I want water to drain out of it (slowly). It's below the water table level so water will almost certainly get in there.
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Very rarely used. Split a LBC common for the first course.
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stuart45 said:
Very rarely used
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Never seen it used, a former bricklayer I worked with didn't even know what it was. brick IC are pretty rare now anyway, I can't remember the last time I saw a newly constructed one.
 
Peter500 said:
I want to make sure it isn't water tight as I want water to drain out of it (slowly).
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The whole point of a manhole (apart from access) is to retain all the crap if it fills up, and not let it escape to contaminate the ground around it.
 
If I remember correctly the BS required a brick manhole should be water tested to 3 course above the benching, not that anyone ever bothered apart from a couple of jobs with Clerk of Works on them, CoW's nearly as rare as a Marscar bowl these days.
 
^woody^ said:
The whole point of a manhole (apart from access) is to retain all the crap if it fills up, and not let it escape to contaminate the ground around it.
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There will be nothing to contaminate the ground around it. Would the same apply if it was only housing electrical cables? Also the pipe is carrying clean rainwater, and it's on its way to the soakaway, which is right next to the manhole (small gap between them). So, in the worst case scenario it was act as an inefficient soakaway. If it had foul water then I would definitely want to contain it. If I seal it, then if there's a tiny leak anywhere then there would be nowhere for it to drain out.

Can I do two stretched courses rather than English bond? It would take me a lot longer to do English bond due to the extra cuts etc. I'm quite surprised that a single skin wouldn't be strong enough and would have thought a double skin would be more than enough. It's at the bottom of my garden so I wouldn't be able to get a car on it even if I tried, it'll just be people walking over the lawn.
 
Peter500 said:
There will be nothing to contaminate the ground around it. Would the same apply if it was only housing electrical cables? Also the pipe is carrying clean rainwater, and it's on its way to the soakaway, which is right next to the manhole (small gap between them). So, in the worst case scenario it was act as an inefficient soakaway. If it had foul water then I would definitely want to contain it. If I seal it, then if there's a tiny leak anywhere then there would be nowhere for it to drain out.

Can I do two stretched courses rather than English bond? It would take me a lot longer to do English bond due to the extra cuts etc. I'm quite surprised that a single skin wouldn't be strong enough and would have thought a double skin would be more than enough. It's at the bottom of my garden so I wouldn't be able to get a car on it even if I tried, it'll just be people walking over the lawn.
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You can do build it how you like.

But if you want to build it properly, then the details are above.
 
Peter500 said:
Do you know whether building control will care how it's built?
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I've always insisted on it as does every BCO I know. but I've never bothered to look to see where it is specified. So I've just had a look at BS 8000 part14 (my old employer has never changed the password to access the on line technical info service) and its specified there, it also states that it should be water bond.
 
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