In message ,
writes
On Wednesday, September 27, 2017 at 9:23:00 PM UTC+1, Tim Lamb wrote:
In message ,
writes
my understanding is building a course or two of double skin with
cavity and is intending to fill that cavity with concrete. Then one
end of the beams will rest on some width of this blockwork and then
the rest of the wall of the extention will be built above that.

sounds about right

Where the other end of the beams will go (by the existing house wall)
he has exposed the sticky out bit of the foundations the house was
built on (1948 Local Authority 3 Bed Semi) and had (as of last night)
built a single skin of blocks butting against the house wall. I
don't know if this is sufficient to support one end of the beams??

I've just had a 2 storey extension done as above.

Apparently builders prefer block and beam as they get less aggravation
from BC about preparation for oversite concrete. The blocks need to be
set with cement slurry. Normally just brushed over the top.

You mentioned ventilation upthread. This requires Z shaped vents as the
void will be below the damp proof course.

Dunno, suggest you take photos each morning ...

Ditto the photos bit:-)

If you don't have the BC paperwork the normal stages for inspecting an
extension a-

Notification of commencement, Foundations, oversite, drainage, floor
joists, steelwork, roof carcass, insulation, windows, completion
notification.

You don't have oversite or floor joists but he might like to see the
block and beam + vents.

One issue I had with our builder was him failing to fit opening closures
prior to the windows and doors being fitted.

--
Tim Lamb

Hi Tim,

Pray tell me about these opening closures. (Sorry if it should be
obvious, but I don't know what you mean).

The window and door openings will show the cavity between the inner and
outer leaves of your new wall. You should find it full of Rockwool
insulation. The cavity closure is a plastic extrusion like a T with a
very fat leg containing expanded polystyrene insulation.
Example here
https://www.uktradefix.co.uk/100mm-m...r-2-4mtr.html?
utm_source=google_shopping&gclid=EAIaIQobChMIkvu_p Y3I1gIVxZ3tCh3x7wUqEAQY
ASABEgLYd_D_BwE

The purpose is to prevent cold bridging across the cavity.

--
Tim Lamb