Water in footings, advice before laying concrete

leebrom · Post: # 19762Post **leebrom** Tue Jun 12, 2007 10:14 pm

Hello folks
I'm sure this has been covered before, but I am requiring advice please.

Currently digging base for conservatory. 18ft by 9ft. Digging down approx 18 inches (for centre raft). Going to lay a 10ml to dust aggregate, sand, viscoene, 4inch of insulation then 4 inch concrete. Conservatory is floor to ceiling glass, so no dwarf wall. Plan to build single skin wall 3 bricks deep (one layer below DPC) onto 30cm deep by 50cm wide concrete footings.

The centre raft/insulation will sit on the concrete footings for the raft facing wall.

Problem is, the water table is quite high in one of the footings. The ground where the footings will be layed is therfore quite "squidgy" I had hoped to pump out the water, put in some brick/aggregate/concrete slab to spread the weight of the concrete footings, then lay the concrete footings (30cm by 50cm, to put on my 3 brick high facing wall for the raft.

I had planned to perhaps install an inspection hole nearby and install a dirty water pump on a permanent basis. There is a drain nearby.

Is this an acceptable proposal in view of the fact that the raft itself is not going to be taking much weight (no dwarf wall) other than perhaps the weight of building materials used.

I also plan to keep the plastic toilet drain (well buried) underneath the raft, as there simply is no other place to put it.

Sorry for the long thread, but cannot afford to get in builders. Can anybody offer some advice to this poor nurse who is pulling his hair out ??

Free drinks (virtual, of course) all round from this newbie.

Regards, Lee

Wed Jun 13, 2007 12:16 am

i cant see any problems with your plan,make sure you lintel over any drain run and as long as you lap the visqueen (DPM we call it) over the 3 courses everything looks ok
cheers LLL

leebrom · Post: # 19894Post **leebrom** Sat Jun 16, 2007 10:24 am

Thanks for your advice, most appreciated. Is it essential that I get things inspected by building regs ? after all, The door through to the conservatory will be a permanent patio door (weatherproof etc) so the conservatory can be classed as a temporary structure (I guesss ?). Similarly, when I had a concrete drive laid, that was laid over drains. I didnt need an inspection for that, and it has 2 cars parked on it. ??

Regards

Lee

Sat Jun 16, 2007 4:19 pm

its always best to do it right lee
theoretically your foundations will be deeper on the conservatory than the drive way,plus the load of the car is spread over a greater area on a driveway
use the lintels mate they cost peanuts compared to a broken sewer
cheers LLL

leebrom · Post: # 19962Post **leebrom** Mon Jun 18, 2007 10:48 am

Thanks for your advice mate. Shall use lintels over the drains and take extra care to ensure drainage through footings is re-inforced with concrete lintels and packed properly with gravel/sand. I have dug an inspection hole and placed in a dirty water pump. This pump is the dogs, and it is pumping away like billy-o (for 24 hours now, at over 10L per min). There are no burst water pipes in the vivinity. How long can I expect this to continue, or do I not have to worry about it too much as long as the footings are dry when I lay the concrete. This must be water table that I am pumping, and therefore, theoretically, I may be pumping for ever to try to get it dry ? Whilst I use the pump in the vicinity of the footings but not in them, it is keeping the footings dry. If I sing an inspection drain where the pump is now, say a 2 footish manhole, whack in a pipe with a lesser diameter (enough to house the pump) and surround it with gravel, this wilol act like a natural filter for me to turn on my pump at any sign of excess water. is this a futile step ? and will the water table level itself out and not affect my conservatory footings ??

Sorry to drain (d'oh) on your knowledge and offer very little in return.

regards

lee

Mon Jun 18, 2007 5:01 pm

hmmm
is the site in low lying land or near a stream/river?
as long as there is no water when you pour the foundation it should be ok but it sounds like you need some land drainage
a properly constructed land drain sounds like it may be in order but without seeing the site its impossible to tell
cheers LLL

leebrom · Post: # 20055Post **leebrom** Thu Jun 21, 2007 3:43 pm

Thanks for your reply LLL

I have isolated both mine and the neighbours water mains, and this makes no difference. I had thought maybe there was an underwater stream running between the 2 houses. A neighbour states that the area is a peat area, and therefore is waterlogged. The houses are built on an old rugby pitch. It is therfore low lying. i think that the water is probably water table.

I had considered running a 4 inch land drain pipe around the footings (not inside them). the pipe is the flexible pipe peppered with holes. Sinking it in a bed of pea gravel (or similar) and running it to the drains.

Does this sound feasible ? We have never had a massive problem with waterlogging, however, when I dug the footings the problem became evident. I think that as it has never been a problem, and as water will always find its own level, once the concrete is in there shouldnt be a problem. The only weight will be the building materials, so if I put aggregate where the ground is squishy (now drying) and maybe a concrete lintel to spread the weight of the footings, theoretically, and looking at engineering principles, I should be ok. I am, however, a nurse, and not a builder.

Thnaks you for your advice. When I am next in Luton I shall look you up, inspect your house, and buy you a pint.

Thu Jun 21, 2007 6:10 pm

tony mc prolly knows the geology of oop north better than me,but if you have never had any water problems then maybe it is the water table
make sure your dpc is 150mm minimum above the ground level
btw i live in a caravan m8 :;):
LLL

andpartington · Thu Jun 21, 2007 9:08 pm

now lll are you trying to tell us something???

do you pull it being that cabster and park in fields and carparks

???

andy

leebrom · Post: # 20115Post **leebrom** Sat Jun 23, 2007 10:32 am

Thanks for your advice LLL. Am finishing footings today. Setting drains in gravel, sand and whacking lintels in-situ. Footings drying out due to peach marksman pump.

Shall let you know when project is finished and post some pics.

Thu Jun 28, 2007 9:14 pm

do you pull it being that cabster and park in fields and carparks

just waiting for my orange light and motorway maintainance sticker
LOL
LLL

andpartington · Fri Jun 29, 2007 4:07 pm

and don't forget the tree chiper and 8by 4s to increase the amount of sh1t u can fly tip

andy

Post: # 20321Post **Dave_L** Sat Jun 30, 2007 9:21 am

lutonlagerlout wrote:
do you pull it being that cabster and park in fields and carparks

just waiting for my orange light and motorway maintainance sticker
LOL
LLL

...........and don't forget that 'left over' tarmac from a big job for the council you are doing......

Stuarty · Post: # 20347Post **Stuarty** Sat Jun 30, 2007 6:10 pm

some rather pleasent folk, employed by a contractor im know of were caught by a family member fly tipping on my little road through the week. Pallets, some left over bricks and a few cut up ton bags. They shall be coming back next week to remove it, and if the claim it wasnt them, they were caught on camera

'Say cheese' lol

leebrom · Post: # 20469Post **leebrom** Thu Jul 05, 2007 6:26 am

Hi LLL
Footings now laid, area seems to be remaining dry and despite recent deluge, water table not causing a problem. Plan to sink an inspection chamber for future use if required. Will sinking a tube into a deep(ish) hole suffice, surrounding the peppered tube with 10mm aggregate (for filtration) be ok?. Any future problems with water table/waterlogging will allow me to whack in a pump and drain it all off. The hole will be next to my house and close to the footings.
Regards
Lee