Building and planning details

[steven williams]

Hi all just a quick question for u all. Iv been bricklaying for 19yrs now so I’d like to think I know what I’m doing lol. Iv worked on site for the last 17yrs and been doing my own thing for 2yrs. I recently found out off a building inspector that building regs on site r diff to extensions etc ‍. I done footings for a extension and conc cavity fill 225mm below dpc. He then told me it’s to high so I now have to put a dpc tray in, if I kept the cavity fill 300mm down I wouldn’t need cavity tray. I would put it in if it was 225 or 300. I then ad plans from the same department for a different extension and it stated the cavity fill should b 150mm below dpc with no cavity tray ‍. What’s your opinion on this? Mine is building inspectors and planning don’t av a clue what they r doing

 

[stuart45]

It's 225mm below DPC where I live. Going back in time before you picked up your trowel it was 150mm, but some of the cavities where getting blocked up over DPC.

 

[steven williams]

I just think building inspectors make things up as they go along

 

[stuart45]

Some of them seem to interpret the regs differently to others, but you can challenge them if you think they are wrong.
NHBC guidance is at least 225mm below DPC, although in some cases it can be 150mm.

 

[^woody^]

The same regulations cover site and home extensions, the only difference is in commercial and domestic construction.

The thing to remember is that the regulations are not specific and do not say "you must fill to 225 or 300 below DPC", rather they say something like "there must be a suitably drained cavity to prevent moisture ingress".

So the clear cavity can depend on the floor type, the insulation type, and the ground level.

 

[stuart45]

I just think building inspectors make things up as they go along

Now you don't work on site anymore it would be worth finding a private BCO that you can work with.

 

[Notch7]

Hi all just a quick question for u all. Iv been bricklaying for 19yrs now so I’d like to think I know what I’m doing lol. Iv worked on site for the last 17yrs and been doing my own thing for 2yrs. I recently found out off a building inspector that building regs on site r diff to extensions etc ‍. I done footings for a extension and conc cavity fill 225mm below dpc. He then told me it’s to high so I now have to put a dpc tray in, if I kept the cavity fill 300mm down I wouldn’t need cavity tray. I would put it in if it was 225 or 300. I then ad plans from the same department for a different extension and it stated the cavity fill should b 150mm below dpc with no cavity tray ‍. What’s your opinion on this? Mine is building inspectors and planning don’t av a clue what they r doing

Is there anything about that extension which may require it - external ground level, sloping site, internal finish floor level, slab construction and insulation position etc etc.

building regs are a mixture of prescriptive and performance based and are open to interpretation to allow for different circumstances.