I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours. The neighbour
is worried that the demolition may damage her side. I guess the roof
may have rebar in. Build around 1920s. Obviously a heavy roof falling
at an angle could take it's 9" support wall with it. I guess I need to
slice it with a diamond cutter. It needs to be as flush as possible to
the 9" wall it rests on. I will be attaching the inner skin of a cavity
wall to the old wall.
What is the best/safest way to take this roof off ?
Cheers,
Simon.

"sm_jamieson" wrote in message
oups.com...
I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours. The neighbour
is worried that the demolition may damage her side. I guess the roof
may have rebar in. Build around 1920s. Obviously a heavy roof falling
at an angle could take it's 9" support wall with it. I guess I need to
slice it with a diamond cutter. It needs to be as flush as possible to
the 9" wall it rests on. I will be attaching the inner skin of a cavity
wall to the old wall.
What is the best/safest way to take this roof off ?
Cheers,
Simon.

I had exactly the same quandary a few years ago while building my extension,
I thought about a diamond disc cutter but thought I'd have a go first with a
lump hammer.
As the concrete was pretty old and not that strong a mix, I managed to
nibble away bit by bit - being more careful the closer I got to their part
of the roof and all went well.
I must admit that I was a bit worried that it would all come tumbling down
in a cloud of dust (me included) but I got quite a good edge in the end.
My extension ended up a couple of inches shy of their section so I used some
flashing to bridge the gap.
While it went ok for me - if I was to do it again I would not try to save
pennies on hiring the proper tool and use the disc cutter to at least give
me a line to break to - a bit more peace of mind.
Good luck.
Franko.

Disc cutter is definately the way to go. The saw-cut will not only seperate the two slabs, but will help minimise the noise and vibration transfered throught to your neighbours property. However, if you are cutting flush with the 9 inch wall it spans on to prior to breaking out the roof, you will need to place a forrest of acrow props underneath to temporarily support it while you demolish it.

Otherwise, demolsih up to a foot away from the support and then saw cut the last bit. Be careful which way you demolish it though! Check which way it spans and break the slab in strips parallel.

Hope this helps!

sm_jamieson wrote:
I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall.

Is this some sort of add-on to the back of your houses?


The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours.

Sounds likely.


The neighbour
is worried that the demolition may damage her side. I guess the roof
may have rebar in. Build around 1920s. Obviously a heavy roof falling
at an angle could take it's 9" support wall with it. I guess I need to
slice it with a diamond cutter. It needs to be as flush as possible to
the 9" wall it rests on. I will be attaching the inner skin of a cavity
wall to the old wall.

How will you prevent water ingress to her side when you've done yours?


What is the best/safest way to take this roof off ?

Piecemeal, not damaging her side.

Pictures?

Chris Bacon wrote:
sm_jamieson wrote:
I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall.

Is this some sort of add-on to the back of your houses?

Yes, there is a sticking-out bit of the kitchen (no slab over), with a
door to a wash-house and finally an outside toilet. The wash-house and
outside loo have the slab over - it supported a water tank originally.



The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours.

Sounds likely.


The neighbour
is worried that the demolition may damage her side. I guess the roof
may have rebar in. Build around 1920s. Obviously a heavy roof falling
at an angle could take it's 9" support wall with it. I guess I need to
slice it with a diamond cutter. It needs to be as flush as possible to
the 9" wall it rests on. I will be attaching the inner skin of a cavity
wall to the old wall.

How will you prevent water ingress to her side when you've done yours?

Initially with tarpaulin etc. I am building an extension that will join
to the exposed party wall with an inner leaf of cavity wall.



What is the best/safest way to take this roof off ?

Piecemeal, not damaging her side.

Pictures?
I will be posting pictures of this whole job soon. I seem to have been
harping on about it for ages !

I think it may be a good idea to first remove the bulk of the roof by
taking out
a square from the middle with a diamond cutter, supporting the chunk
from beneath and then lowering it. This would keep the weight balanced.
Cheers,
Simon.

In article .com,
sm_jamieson wrote:
I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours. The neighbour
is worried that the demolition may damage her side.

Check your insurance to see if they'll pay up should
it all go horribly wrong... :-)

Seriously, thinking about it, it's worth checking.
If it collapsed some time later on then there could
be huge liabilities.

G.

G.W. Walker wrote:
In article .com,
sm_jamieson wrote:
I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours. The neighbour
is worried that the demolition may damage her side.

Check your insurance to see if they'll pay up should
it all go horribly wrong... :-)

Seriously, thinking about it, it's worth checking.
If it collapsed some time later on then there could
be huge liabilities.

G.

Yep. Which raises some questions about DIY / insurance etc.
I will start another thread about it.
Simon.

In article .com
sm_jamieson wrote:
I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours. The neighbour
is worried that the demolition may damage her side. I guess the roof
may have rebar in. Build around 1920s. Obviously a heavy roof falling
at an angle could take it's 9" support wall with it. I guess I need to
slice it with a diamond cutter. It needs to be as flush as possible to
the 9" wall it rests on. I will be attaching the inner skin of a cavity
wall to the old wall.
What is the best/safest way to take this roof off ?


I'd try it like this:

2 1
-------+--------------------------------+---------------
| | |
-----------------------+--------------------------------
===== 3 ===== | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |


Support the slab with Acrojacks and boards.
Make the cuts in the order shown - when cutting 3 you may want to prop
it with bits of timber as you go, and pull the props away with rope once
you're out of range.
Then whack it from above, standing on the party wall so you don't go
down with the rubble.
Finally remove manageable chunks to tidy up the remaining edge.
Don't blame me if you get squashed - I'm not known for the safety of my
exploits.

Rob Morley wrote:
In article .com
sm_jamieson wrote:

I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours. The neighbour
is worried that the demolition may damage her side. I guess the roof
may have rebar in. Build around 1920s. Obviously a heavy roof falling
at an angle could take it's 9" support wall with it. I guess I need to
slice it with a diamond cutter. It needs to be as flush as possible to
the 9" wall it rests on. I will be attaching the inner skin of a cavity
wall to the old wall.
What is the best/safest way to take this roof off ?


I'd try it like this:

2 1
-------+--------------------------------+---------------
| | |
-----------------------+--------------------------------
===== 3 ===== | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |

doing that would cause the roof to expand sideways with great force,
I'd avoid that. I also wouldnt be too happy cutting no 3 while standing
under it!

Dynamite would ensure the pieces coming down were small enough not to
bring any wall down. But....

I'm unclear about the exact layout of all this, so dont take anything I
say as gospel here. But obviously you need to ensure the old roof gets
adequate support at its new boundary end.

After cutting on the boundary to isolate the neighbour's roof, I'd prop
yours with timber then cut panels of roof out, then when the last bits
come down there's no chance of it knocking an end wall out. Timber
could be screwed to the crete roof to keep it there, or made into a
frame with some extra bits. Acros are more money and probably no easier
or quicker in this case, plus to support a sloping roof you'd still
need to attach them to something so they cant move.


NT

In article .com
wrote:
Rob Morley wrote:
In article .com
sm_jamieson wrote:

I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not connected
to the house) and may run across mine and the neighbours. The neighbour
is worried that the demolition may damage her side. I guess the roof
may have rebar in. Build around 1920s. Obviously a heavy roof falling
at an angle could take it's 9" support wall with it. I guess I need to
slice it with a diamond cutter. It needs to be as flush as possible to
the 9" wall it rests on. I will be attaching the inner skin of a cavity
wall to the old wall.
What is the best/safest way to take this roof off ?


I'd try it like this:

2 1
-------+--------------------------------+---------------
| | |
-----------------------+--------------------------------
===== 3 ===== | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |

doing that would cause the roof to expand sideways with great force,
I'd avoid that.

I was anticipating that the outer (non-party) wall would allow
sufficient movement (and possibly come down at the same time!) - maybe I
should have been clearer on that. But you're probably right that it's a
bad idea.

I also wouldnt be too happy cutting no 3 while standing
under it!

As I said, timber props might be a good idea :-)

Rob Morley wrote:
meow2222 wrote:
I also wouldnt be too happy cutting no 3 while standing
under it!

As I said, timber props might be a good idea :-)

Just bash the bliddy thing off in bits, and cut off when
close to finish. It sure ain't worth all the pain.

Rob Morley wrote:
In article .com
wrote:
Rob Morley wrote:
In article .com
sm_jamieson wrote:

I'd try it like this:

2 1
-------+--------------------------------+---------------
| | |
-----------------------+--------------------------------
===== 3 ===== | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |

doing that would cause the roof to expand sideways with great force,
I'd avoid that.

I was anticipating that the outer (non-party) wall would allow
sufficient movement (and possibly come down at the same time!) - maybe I
should have been clearer on that. But you're probably right that it's a
bad idea.

50/50 which end gives.

Thinking a bit more here, you'll only need one prop in total. Each
crete panel thats cut out is cut top and bottom first, then side, so no
prop needed. Only the last panel needs a prop since its not supported
by crete on one side.


NT

sm_jamieson wrote:
I will be demolishing an outhouse/kitchen that is joined to the
neighbour's by a party wall. The roof is a concrete slab (not
connected to the house) and may run across mine and the neighbours.
The neighbour is worried that the demolition may damage her side. I
guess the roof may have rebar in. Build around 1920s. Obviously a
heavy roof falling at an angle could take it's 9" support wall with
it. I guess I need to slice it with a diamond cutter. It needs to be
as flush as possible to the 9" wall it rests on. I will be attaching
the inner skin of a cavity wall to the old wall.
What is the best/safest way to take this roof off ?
Cheers,
Simon.

As an extra piece of information WRT cutting versus hammering, my advice is
to not put a hammer anywhere near it until you have cut completely through
the thickness of the concrete (I'm guessing it's 4 inch?) - for this you
will need a diamond disk and preferably a petrol driven sthilsaw.
Any hammering, chiseling etc will leave hairline cracks all over the entire
slab, soon noticable when it rains in.