Will my garage base be thick enough to build brickwork on?

[JohnHamer1977]

Hi all,

I'm about to apply for permission to get a lean-to build at the side of my house.

Done some rough pics (see links)

The sub-base was MOT1 whacker'd down, then 1500 DPM, then 100mm of garage base concrete.

Would that be enough to build on or will the council people make me cut out deeper trenches and new footings?

Thanks

 

[Robert too]

Definitely new foundations required imho

 

[JohnHamer1977]

Right OK

I am guessing that I can cut away a trech, dig lower and fill that?
How deep do the footings have to be?

 

[noseall]

it is a b.c. requirement to dig down 1m below ground level.

in a lot of cases 600mm is sufficient, though it will depend largely upon local ground conditions.

if in future you think you may want to build on top of the existing garage then a full reg's footing may be wise.

 

[JohnHamer1977]

Right, so we can pretty much say that my slab only goes 300mm down so it deffinatly not going to be enough.

So am I undrstanding that if I go a full 1 meter that would potentially be enogh for a double extention if I wanted to build up in the future?
If so, might be worth doing.

But the other option is go down to good ground and you say normally about 600mm and that's enough for a normal single extention?

Won't I hit services at that sort of depth though (I mean the 1m deep)?

thanks for the help

 

[BREAKALEG]

A little off topic but how did you get the images of your house? looks really usefull.

 

[JohnHamer1977]

Nah, it's on topic mate... no worries

I used a free program called google sketch up.

It's very easy, you draw a basic flat shape, then use a pull out button click on the surface you want to pull out and pull it - that's it!!!

Then use lines or even circles in the same way... just draw them and pull them into a 3d shape.

 

[Static]

Right, so we can pretty much say that my slab only goes 300mm down so it deffinatly not going to be enough.

So am I undrstanding that if I go a full 1 meter that would potentially be enogh for a double extention if I wanted to build up in the future?
If so, might be worth doing.

But the other option is go down to good ground and you say normally about 600mm and that's enough for a normal single extention?

Won't I hit services at that sort of depth though (I mean the 1m deep)?

thanks for the help

Width of footing dictates the amount of load it will carry not really depth.. in most cases the first couple hundred mm of ground is topsoil (extremely weak) followed by made ground (fairly weak) followed by the natural ground below (normall fairly strong).
What you should really be doing is matching the depth of the existing house footings. These may be 1m to 3m down. You should be founding in "good ground" anyways, unless you dont mind repairing cracks every year.
Yes you may hit services, most services into a property are between 300-800mm down, drainage on the other hand can vary alot.. you have at least 1 gully and 1 rwp to pick up so there is a strong chance a surface water drain runs through that area, just check the mainholes each end. Then mark out the pipe location before digging.

 

[JohnHamer1977]

OK.

I will be getting the builder to do the digging then as that's a lot further than I am capable of doing...

you say the width is more important?
I don't fully understand that (sorry if I'm being dumb)
so are you saying the slab I have layed might be ok to build on as that is 3m wide?

I will be getting the council inspecters to check all this out with anyway so no worries, I'm just after guidence here really so I am prepared and sort of understand what they will recommend doing.

cheers

 

[Static]

Mmmm

Think of it this way then.. if you have a broom handle and lean on it it will sink into the ground easily..
If you glue a cup on the bottom and push down it will be ALOT harder to push it into the ground. Larger surface area means the load is distributed over a larger area.

:/

Anyways the 100thk slab may locally crack where the load it applied as the chances are you didnt put any reinforcement in it or deepen the edges.

Building Control should be able to give you guildance on that to do..

 

[JohnHamer1977]

Still waiting to here back from them... I will phone them again tomorrow.