Conservatory footing depth + general muck shifting questions!

[Army]

Hi all,

I'm planning the footings for our self-build conservatory and need some advice.

I have dug an investigatory hole to see how deep the house foundations are. The house is a 1980s 2 storey detached. So far I have (from DPC down over) three courses of brick followed by three courses of blocks. I haven't managed to dig any deeper yet because the small area of the hole is making it rather difficult. Assuming that there are 3 courses of blocks + 3 courses of bricks that is about 900 to dpc plus I guess about 250m of concrete for the footings. DPC is about 2 bricks height above ground level so that leaves a dig of around 1000.

To be as safe as possible I guess that my conservatory foundations should match the house foundations in depth and construction.

I'm wondering whether this is going to be overkill given that the conservatory with 600 dwarf wall is going to be much lighter than the house.

I will be doing all the work myself. If the foundation trench needs to be 1000 deep to match the house then the conservatory of 3400 x

4000 with a trench width of 450 is going to entail digging away 4.725 cube of earth! Clearly that is quite a lot and if I can safely keep the foundations shallower then that would be great!

I notice that picture 3 on

shows a foundation trench where the blockwork foundations of the main house can be seen thus indicating that the main foundations are much deeper than the conservatories. Is this acceptable practice?

Would anyone care to comment on whether I am taking on too much work for one person here. In addition to the digging for the foundations I will need to strip off some topsoil in readiness for the hardcore, I will have about 1 cube of concrete to mix and pour for the footings, about 1.5 cube of hardcore to move and compact, blinding and insulation to lay and then another approx 1 cube of concrete to mix and lay for the floor, not to mention the brick laying. My QS pal recons that's about 2 weeks work for 2 big lads. I thought that seemed a bit over the top.

Any thoughts, am I mad to even consider it?

Thanks

Mike

[Rick]

I think you need some advice on how much footings to make, you may be best having a slab.

A mini digger will cost you a hundred quid for a weekend, and is MUCH safer. That depth of hole will be nasty if it falls in on you. a mirco digger will do what you need, and will fit through a normal doorway. A mini dumper may help shift the muck if you have any distance to move it.

I mixed & layed 1 cube last weekend, in about 3 hours. If I had chosen a hot day I would have been in trobble. I only did this cause getting a concrete truck is a pain, as it can't get to my house. I would always recommend you get a truck, or a mix & barrow service.

If you are happy for the build to take a while, then its not too much work, if you want it done in a week, you will be dissapointed.

Foundations are the worst bit, once you have dug a massive hole, its full of dangers, its much easier to sleep if you go in hard and fast with decent equipment, and the holes are filled in with stuff asap.

Rick

[Peter Crosland]

Why don't you go and talk to your local building control office? You need their approval anyway AFAIK so be guided by them.

[AlexW]

Not that that is a bad idea, but often then are exempt, quoting my BCO:

"Works exempt from Building Regulations . . . Conservatories ? these must be separated from the dwelling by a door, have at least three quarters of the area of the roof and half the area of the walls made of light transmitting material and should incorporate safety glazing where appropriate."

[Peter Crosland]

Interesting! A friend recently had one installed and the BCO had to approve the footings and base. I would be interested to know if there is a size limit below which there is an exemption.

Peter Crosland

[Andy Hall]

Yes. Less than 30m^2 inside measurements.

The complete list:

1) The conservatory will be used solely for domestic purposes 2) The conservatory is to be built at ground floor level 3) The conservatory will not contain any sleeping accommodation 4) A minimum of 75% of the conservatory roof will be glazed with translucent or transparent materials 5) A minimum of 50% of the conservatory walls will be glazed with translucent or transparent materials 6) The floor area of the conservatory will be less than 30 metres squared (internal measurement) 7) The construction of the conservatory will not affect the existing drainage system 8) The conservatory will not be 'permanently heated' (This can be achieved by thermostatic radiator valves) 9) The conservatory must be separated from the existing property by a wall, door or glazed screen 10) No part of the conservatory shall be within one metre of the boundary of the property

[Army]

Hi Rick. I have since spoken to my local building control dept. The conservatory is of course exempt but he did let me pick his brains re foundation depth. He correctly identified the soil in my area as being of a sandy/gravely consistency and recommended 600-750 to bottom of trench with at least 6 inches of concrete. I was going to lay about 250 of concrete.

A trench of say 700 doesn't seem quite so daunting having done a test dig and having found the soil to be quite manageable so I'm going to manually dig it. I think that I will splash out on the luxury of getting a large skip with a fold down door though!

I think I may owe you big time for that suggestion. I had costed the concrete to mix myself including cement, ballast and mixer hire to be £152 for the 2 cube that I'll need (1 for footings, 1 for slab). I've since found a mix and barrow service who will do one visit for the footings for £132.50 and another trip a week or so later for the slab for £138. This includes barrowing it all around the back of the house. Nearly double the cost but experience has taught me that it is sometimes worth putting your hand in your pocket...

No hurry here!

I have found in my test trench, a horizontal pipe of about 10-15mm diameter. It looks like it is coming from the base of the gutter downpipe so I assume it is a rainwater pipe. Looking at my levels, I think that the concrete footings are going to come up to about level with the centre of this pipe. How does one cope with this? I guess that if the pipe is at brick level then one forms an opening using a concrete lintel for it. If the pipe is at concrete level is it safe just to pour the concrete around it? I would worry about any slight movement breaking the pipe (although I also realise that there shouldn't be any movement at all!) The pipe is thick brown plastic, not ceramic.

Thanks

Mike

[mike. buckley]

In message , Andy Hall writes

Oops.

We fall down on 8, 10 and possibly 5 (one wall is solid as it's close to the fence).

Surely just about every conservatory on a semi or modern build detached will fall foul of 10?

Next time I'm in a shed I'd better pick up a thermostatic valve!

[Peter Crosland]

Remember that if and when you come to sell your house you will be required to prove you have had all relevant planning and building control permissions. Doing it right now will save you time and money in the long run.

Peter Crosland

[manatbandq]

When we thought of having a conservatory the supplier recommended applying for both planning and building regulations if only to receive letters saying we were exempt, within permitted development, etc. It can save some toing and froing if you want to sell in the future.

Father in law was prevented from having a conservatory due to the "45 degree rule". Has anyone heard of that? If a neighbour could see the conservatory when looking out of their window at 45 degrees then it was not allowed. Could it be a local byelaw? It was applied for at the same time as a conventional extension and I suspect something was lost in the translation.

MBQ

[John Cartmell]

Oops for practically every conservatory in the country!