In an earlier contribution to this discussion,
Andrew Welham wrote:

Dear all

After reading the news groups archives and the building regulations
for the past few days. I have made some (but slow) progress in the
design of my extension. What I have so far is:

My house (1960s) semi detached is 6445mm wide and 7130mm in depth
(excluding the porch). I have a side entrance with is 2360mm with at
it narrowest point (including the brick wall which I am responsible
for 450mm wide).
I have a private (I think council not back from Christmas yet) drain
running parallel to the back of my house, with the edge of the man
hole cover being 2680mm from the back of my house (and ending 3200mm
from the back of the house).

I have an old garage in the back garden, which starts 4200mm from the
back of the house. This will eventually be demolished, since it is
made on a solid slab, and I don’t want to loose any more garden this
will turn in the patio after the rebuild has been completed.
Therefore my back wall of the extension must be between 3200mm &
4500mm away from the house. That’s the background out of the way, but
I thought it might be helpful.

The garage will be built in the side entrance and I need it to be as
wide as possible.

Can I assume the 450mm wide brick wall that I am responsible for is on
my land and therefore when I remove this wall my foundations can take
up the space where this wall once sat ?

I am planning for the garage on using 100mm (building regs say 90mm
Min) concrete block in a single leaf wall with from end bonded at
least 190mm(this will also form one side of the door way. The other
end will be bonded to a two leaf wall which will form also contain
dual doors (30 minute fireproof) for access to the extension living
area. The regulations also say there must be piers at a maximum of
3000mm apart since the garage will be 7133mm long I am planning on
having two piers at approximately 2377mm intervals. The doors between
the garage and the main living area will be will have a step not less
that 100mm high, and any pipes entering the garage from the existing
house greater than 40mm will be fire proofed.

Dose this sound ok to every one? Have I missed anything?

I am still looking into the roof. I defiantly want a flat roof to stay
in keeping with the neighbours. I assume I can have a cold roof for
this un-insulated garage? Made up I guess of marine ply and multiply
layers of felt (3 I think).

The roof joists. One end is fixed to the wall I will build out of
concrete block.
The other end I assume is fixed to the house by joist hangers?
One answer I can’t seem to find is,

What do I do about the bit of the garage between the top of the door
frame and the roof? Does this have to be block, and if so what holds
it up or can it be made of wood and fastened in the same way as the
joists?


The garage will be built first then the extension, but while I am
thinking about blocks
The last question in this post, should I and can I use the 100mm
concrete blocks for the inside and outside walls of the main extension
which will be going across the back of the house and garage. I am
planning on rendering the garage and extension to ensure they are in
keeping with the neighbourhood.

Many thanks

Andrew

I'm trying to get my head round this lot - but here are a couple of initial
comments/queries.

Are you sure that the brick wall on the remote side of your side entrance is
450mm (18") thick? What is on the other side? You may be responsible for it,
but I'm not sure that that necessarily means that the boundary is on the far
side of it. I have a feeling that foundations (which will necessarily extend
out further than the outer edge of your new garage wall) need to be on your
land - so it's important to bottom out these issues.

It seems to me - from the dimensions you have stated, that the internal
width of your garage - particularly where narrowed by the piers - may be
insufficient to get a car in or - at any rate - to open a car door once it
is in. This all needs calculating very carefully.

Over the garage door, you could use a wooden frame covered by ship-lap or
similar. Otherwise, you'd need a lintel with blocks above it.

I don't quite understand about the manhole. Is it going to be *inside* the
extension? Is it storm or foul (or combined)? Incidentally, getting an
answer as to whether it is public or private may not be straight-forward -
because many of the records seem to have got lost - in my area at least - in
the local government reorganisations in the 70's or whenever! [You'll
probably find that if you want to build over it, it's public - but if you
want it unblocking, it's private! g]

Your living accommodation extension will need to satisfy all the latest
building regs with respect to thermal efficiency - which requires a high
standard of thermal insulation. I can't quote any U values off the top of my
head - but I imagine that you will be required to use insulating blocks for
the inner layer - and maybe to dry line on the inside of that.
--
Cheers,
Set Square
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