Just got a quote of £60,000 for a 30m2 ground floor + 10.5m2 upstairs
extension, which I think is a bit steep! I'll get more quotes but even
so I've decided to dig my own foundations by hand and lay the concrete,
to save money.

My existing house is built in the bottom of a former limestone quarry.
The top-soil/clay is relatively shallow approximately 500mm, below that
you hit solid limestone bedrock. So it's quite good for building solid
foundations on.

Digging the trench I think will be relatively straight forward
(architect's plan state strip foundation 600mm x 200mm)

I have a number of questions and concerns:-
My biggest concern is making sure the concrete will be level and
uniformly at the same depth (digging the trench to a uniform depth is
relatively easy). I've read about knocking wooden pegs in to the
trench bottom so you can easily gauge concrete levels. But won't they
weaken the foundation if left in which I'm told you do? How about
using Steel pins, where do you purchase them, are they the ones used
for steel reinforcing?

-How do you tamp the concrete easily without sideboards do you use a
"vibrating poker"?

- Should I measure concrete depth to coincide with brick/block
measurements, so that the once the bricks are built up to ground level
they coincide with the existing house brick level?

Any tips websites, books that can give me a full insight into what is
required would be most appreciated.

wrote:

My existing house is built in the bottom of a former limestone quarry.
The top-soil/clay is relatively shallow approximately 500mm, below that
you hit solid limestone bedrock. So it's quite good for building solid
foundations on.

Digging the trench I think will be relatively straight forward
(architect's plan state strip foundation 600mm x 200mm)

I have a number of questions and concerns:-
My biggest concern is making sure the concrete will be level and
uniformly at the same depth

Since you are on bedrock you have no worries about the footings moving.
All you need is a base to run the brick courses to. I wouldn't worry oo
much about gettin the levels spot on. Any competent brickie will soon
put the first couple of couses right.

I've read about knocking wooden pegs in to the
trench bottom so you can easily gauge concrete levels. But won't they
weaken the foundation if left in which I'm told you do? How about
using Steel pins, where do you purchase them, are they the ones used
for steel reinforcing?

You won'r need that will you just fill it to a level and drop a plank
on it and move the concrete around until the plank is floating level.

For anyone putting footings onto clay or shale, the pegs come out after
the bulk of the concrete is poured then the holes filled in. A cpoule
of 3 x 2 run along the trench nailed to the pegs allow the concrete to
be trammelled level.

-How do you tamp the concrete easily without sideboards do you use a
"vibrating poker"?

No need the footings for the wall only need to be scraped level to
withing spitting distance. Of course if there is little of no depth
below DPC to play with you might have to fiddle it. The bricklayers
will just lay thicker and thinner mortar to bring the bricks right.

I have even seen them leaving bricks out of courses and using floor
tiles instead of bricks to make the level.

- Should I measure concrete depth to coincide with brick/block
measurements, so that the once the bricks are built up to ground level
they coincide with the existing house brick level?

Once the bricks are brought to DPC level you can put the hardcore in
the floor and then the binding sand which will need tramping with a
"wakker plate" or roller. Then the visquene does on the day the
concrete comes. I'd get the brickies to float that for you if you are
that unsure.

wrote:
Just got a quote of £60,000 for a 30m2 ground floor + 10.5m2 upstairs
extension, which I think is a bit steep! I'll get more quotes but even
so I've decided to dig my own foundations by hand and lay the concrete,
to save money.

My existing house is built in the bottom of a former limestone quarry.
The top-soil/clay is relatively shallow approximately 500mm, below that
you hit solid limestone bedrock. So it's quite good for building solid
foundations on.

Digging the trench I think will be relatively straight forward
(architect's plan state strip foundation 600mm x 200mm)

I have a number of questions and concerns:-
My biggest concern is making sure the concrete will be level and
uniformly at the same depth (digging the trench to a uniform depth is
relatively easy). I've read about knocking wooden pegs in to the
trench bottom so you can easily gauge concrete levels. But won't they
weaken the foundation if left in which I'm told you do? How about
using Steel pins, where do you purchase them, are they the ones used
for steel reinforcing?

Use anything. You won't get it all level, but thats no big deal. What
yiu do is string up carefully for he first course of brick/block and use
variable mortar beds or half bricks or whatever.



-How do you tamp the concrete easily without sideboards do you use a
"vibrating poker"?

Just rake it around with a rake. Vibration is a way to do it fast but
its not mandatory.

- Should I measure concrete depth to coincide with brick/block
measurements, so that the once the bricks are built up to ground level
they coincide with the existing house brick level?


More or less yes..but remember that half the skill in the first few
courses is to get the courses to align at ground level.

Any tips websites, books that can give me a full insight into what is
required would be most appreciated.

wrote:
Just got a quote of £60,000 for a 30m2 ground floor + 10.5m2 upstairs
extension, which I think is a bit steep! I'll get more quotes but
even so I've decided to dig my own foundations by hand and lay the
concrete, to save money.

My existing house is built in the bottom of a former limestone quarry.
The top-soil/clay is relatively shallow approximately 500mm, below
that you hit solid limestone bedrock. So it's quite good for
building solid foundations on.

Digging the trench I think will be relatively straight forward
(architect's plan state strip foundation 600mm x 200mm)


That's a lot of soil, bearing in mind that they are two foot wide by eight
inches deep at the bottom of the trench, the trench itself will probably be
two feet deep as well.
Aslo don't forget that the bottom of the trench should be widened out to
600mm, so that the shape of the concrete is like this:
________
/ \

for stability.

I have a number of questions and concerns:-
My biggest concern is making sure the concrete will be level and
uniformly at the same depth (digging the trench to a uniform depth is
relatively easy). I've read about knocking wooden pegs in to the
trench bottom so you can easily gauge concrete levels. But won't they
weaken the foundation if left in which I'm told you do? How about
using Steel pins, where do you purchase them, are they the ones used
for steel reinforcing?

You don't need any of that guff, just dig the bottom of the trench fairly
level and drop in the concrete.
To test the levels of the bottom of the trench, get 3X2 timbers and put the
level along them on each run (if for example your trench is in an 'E' shape
or a square 'C' shape) and at each corner.
Pour the concrete in (ask the delivery driver to wet it up so that it runs
more easily) and tamp down with the back of a large rake, this will be level
enough for most brickies, as the others have said, they will gain or lose a
few inches within a few courses and long before they reach DPC level it will
be perfect.



-How do you tamp the concrete easily without sideboards do you use a
"vibrating poker"?

Large rake, or a short length (18inch) of 3X2 fixed to the end of another
piece of timber and tamp it with this, it doesn't need to be polished.

- Should I measure concrete depth to coincide with brick/block
measurements, so that the once the bricks are built up to ground level
they coincide with the existing house brick level?


You can sight it visually, as long as it isn't 6 inches out from one side to
the other, the brickies will sort it out

Any tips websites, books that can give me a full insight into what is
required would be most appreciated.

Thanks for all the advice so far

Here is a prelimanary plan of the new extension (left of existing
house), dimensions (red lines) are approximate:
http://img73.imageshack.us/img73/1793/205gh.jpg

There is a 4" soil drain which will go under the rear wall of the
extension. Do I run the footings to either side of the pipe leaving
approx 6" gap and then the brickies will place a lintel to bridge the
pipe?

wrote:
Thanks for all the advice so far

Here is a prelimanary plan of the new extension (left of existing
house), dimensions (red lines) are approximate:
http://img73.imageshack.us/img73/1793/205gh.jpg

There is a 4" soil drain which will go under the rear wall of the
extension. Do I run the footings to either side of the pipe leaving
approx 6" gap and then the brickies will place a lintel to bridge the
pipe?

Yes. That is one way. Another, after you have checked your levels, is to
run the pipe OVER the footings and construct a brick and lintel arch
over it.

In general bricks should go from perhaps a couple of courses below
ground level to a couple or three above it, before you insert the DPC,
which is usually at or about finished floor level.

The higher your soil pipes can exit the steeper the run they will have
outside. Conversely the shallower they will have inside..so its a fine
point as to where they should go,

BUT try always to get to 1:60 drop. You *can* get away with less, but
thats a good target to aim for.

You should gravel it up as well

On 23 May 2006 09:23:01 -0700, a particular chimpanzee named
" randomly hit the
keyboard and produced:

There is a 4" soil drain which will go under the rear wall of the
extension. Do I run the footings to either side of the pipe leaving
approx 6" gap and then the brickies will place a lintel to bridge the
pipe?

No. You will need to excavate below the pipe, making sure that if the
footings are stepped down, the concrete overlaps by twice its
thickness, and leave at least 50mm clear between the pipe and the
concrete. The wall is then lintelled over as you describe.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"