On Jun 12, 2:49*pm, John Williamson
wrote:
Richard wrote:
On 12/06/2011 10:30, Richard wrote:
On 12/06/2011 09:48, John Williamson wrote:
Richard wrote:
Let's imagine that I want to buld a wall 5 bricks long and 12 courses
high.

http://www.ibstock.com/highlights-brick-calculator.asp

You see, on the brick calculator, that if I did that the area is
exactly 1 square metre. You also see that it would take 60 bricks.
That tallies with the brick quantities on page 13 of Ibstock's Guide
to Good Practice cataligue.

What I understand is, that if I built the same wall, 5 bricks long and
12 courses high, but English bond, I'd use 86 bricks. Or, Flemish
bond, 77 bricks.

But, if I use less bricks, because I choose Flemish over English bond,
say, I must use more mortar. That's what I think is the case. If
mortar is more expensive than brick, it would be more expensive to
build with less bricks.

Or, am I making a mistake somewhere?

Possibly. We always used to order the same number of bricks for a 215mm
thick wall, no matter what the bond, ignoring minor stuff like chopping
bricks in half for odd sized holes and corner bonding. The calculator on
the page is for 102mm thick walls assuming that for each header, you use
a complete brick, throwing away the other half brick. There may be an
allowance in their calculations for spoilage when the bricks are cut.

For 215mm thick walls, it's about 120 bricks per square metre when you
order them. For 102mm walls, it's about two thirds of that, due to
wastage when cutting to make short headers. The bits that get cut off
normally end up filling the bottoms of trenches as hardcore.

The other thing is, you don't build brick walls to exact metres, you
design and build them to multiples of 112.5mm horizontally, with 10mm
allowances for mortar joints being missing at the ends, and 75mm
multiples vertically, with 10mm allowance for the missing mortar joint
on top.

I just drew out two walls, both 5 bricks in length and 12 courses high..
In area both 1 square meter (5 bricks long, 12 courses).
Here are my results:

STRECHER BOND:-

Uncut bricks used: 54
Half bricks used: 12(6 bricks)
Total bricks required: 60

ENGLISH BOND:-

Uncut bricks used: 30
Half bricks used: 54 (27 bricks)
Quater bricks used: 12 (3 bricks)
Total bricks used: 60

http://www.ibstock.com/pdfs/guide-to...good-practice-....

Okay, on page 13, for stretcher bond it says you need 60 bricks for a
half brick wall. But, why does it say you need 86 bricks for English
bond with same area? Have I not just proved that you still only need 60
bricks?

Okay, I just got it.

When you make the English bond, each header uses up one full brick. You
cannot make two headers from one brick. That is how the calculation has
been made out.

So, with a half brick wall, you wast a lot of brick.

Pretty much, yes, except for stretcher bond, which is what's used mostly
for "half brick" walls. If it's a half brick wall with the back hidden,
then quite often the headers are just left sticking out of the back.
Eleven inch cavity walls such as were used for houses in the fifties or
for decorative walls now are made from two stretcher bond skins fastened
together with wire ties.

With a full brick wall, there will be considerably less waste as you
don't have to cut a brick for the headers, you can just use a full brick.

In my opinion, those quantities ought to be given for a brick wall (not
half brick as they are). Because I would have though no-one constructs a
half brick English bond wall (I imagine).

Not from choice, anyway, though the architect or client may specifiy
that that's what they want.

As one poster has said, British brick sizes were designed for feet and
inches, and square yards, with four facers or eight headers per linear
yard, and four courses to the foot. This gives 48 bricks to the square
yard for stretcher bond, half a brick thick, or 96 per square yard of
nominal 9 inch brickwork (any bond), the calculations in the brochure
may have been converted from this just by multiplying by the appropriate
factor of about 1.2. In real life, it's not so easy.

Work it out for chinese bond and other hollow bridged walls and you
get a different figure again.


NT