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Posted: Sat Jun 02, 2007 6:10 pm
by Helpneeded
We are hoping to fit a conservatory. The conservatory will be built on our patio under which our foul drain pipes run. I have old plans which show the pipes to be quite shallow gradient of 1:60 so have worked out that the pipe is only 190mm below ground level, where the pipe meets the SVP indoors. We have a high water table.
The conservatory wall height is some 3m so to avoid crossing numerous upstairs windows we need to lower the floor level in the new build and would like to do the same in the old part of the house.
My question is if we are restricted height wise what is the advice re minimum floor level over a pipe. Alternatively can we lay a foul drain pipe flat and add a pump to pump the waste away?
Hoping to receive options but please note I am technically challenged.
Posted: Sat Jun 02, 2007 7:49 pm
by flowjoe
Not quite sure what the water table has to do with the drain depth, if they managed to put you house foundations in.
At the end of the day you have a pre-determined level to work to, that is the level of the drainage system around the property.
If the new build slab/foundation is lower than the existing drainage system and you can not divert the soil vent pipe, then you will have to install a pump chamber.
I would always go for the gravity option where possible, as it nearly always works, however the modern pump systems are pretty good but you will have to keep an eye on it.
I would add that you should get a specialist contractor in to sort this out, in my experience drains and drainage are things that get in the way for most conservatory guys so they tend to go for the quick fix in order to finish the job and take the £££
Posted: Sun Jun 03, 2007 12:34 pm
by lutonlagerlout
why does the conservatory wall need to be 3m??
your floor no matter where it is needs to be 150mm above the existing finished ground level outside
i have done dozens of conservatory bases and the height of the wall can be anything from DPC to about 3m
normally for a 3m wall you would dig your foundations 1m deep ,concrete higher than the pipes ,
and lintel over the pipes with 65mm precast lintels allowing 150mm bearing both sides
bit of an odd one this???
hope this helps LLL 
Posted: Sun Jun 03, 2007 1:04 pm
by Helpneeded
Hi LLL
Thanks for the replies.
I didn,t mention before that the conservatory is to have floor to ceiling glass with a deep plinth on top hence the height is set at 3m. We intend to knock the wall down between the existing kitchen and the new conservatory to make one room so ideally need the floor all to be at the same level.
Do I understand your reply correctly. the pipe being 190mm below ground level may not be a problem just as long as I can achieve 150mm concrete encasement.
Posted: Sun Jun 03, 2007 8:14 pm
by lutonlagerlout
if the pipe is 190 mm below ground you shouldnt really have any problems
main thing is to avoid any extra loading on the pipe
i cant really do drawing on this but if the pipe is 190 mm below ground level then i cannot see any competent person having any issues at all
the plinth that you speak off still needs to be 150mm above ground level with DPC on top of the plinth
cheers LLL