Module 2 of 2 · 45 minutes
Setting out and bonding: getting the first course right
By the end of this module you will be able to
- Set out a wall to gauge and explain why bricks are the sizes they are
- Lay a stretcher bond correctly, including the half bat at the ends
- Use a line, level, gauge rod and plumb correctly
- Recognise the common bonds and where each is used
Work through it
2 interactives for this module, built on the WAJD Teach engine. Nothing moves until you ask it to, and every one has a written version if you would rather read it.
Amara Why is a brick the size it is? It looks completely arbitrary.
Nadia It looks arbitrary until you add the joint. A standard brick is 215 long, 102.5 wide, 65 high. Add a 10mm joint to the length and you get 225.
Amara And the width?
Nadia Two widths plus a joint. 102.5, plus 102.5, plus 10, gives 215. Which is exactly the length of a brick.
Amara So a brick laid across the wall is the same length as one laid along it.
Nadia That is the whole system. Without it, bonding is impossible. And the height does the same thing: 65 plus 10 is 75, so four courses rise 300mm exactly. That is your gauge, and it is the number you check against all day.
Amara Where do people go wrong?
Nadia The first course, almost always, and nothing you do afterwards rescues it. If the bottom is out, you spend the rest of the wall cutting bricks and fudging joints to hide it, and it shows anyway.
Amara So what do I do before I mix anything?
Nadia Set it out dry. Lay the entire first course on the foundation with no mortar, leave 10mm gaps, and see where it lands.
Amara And if it does not come out even?
Nadia Then you adjust the joint widths very slightly across the whole run. A millimetre here and there across twenty bricks is invisible. What you must not do is take up the whole error in one place and cut a horrible little slip of brick at the corner, because that is the first thing anyone's eye will land on for the next fifty years.
Amara How do I keep a long wall straight?
Nadia You do not try. Build the ends first, several courses high, racking them back so they step. Then run a string line between them at the top of each course and fill in between.
Amara That feels like more work.
Nadia It is far less. Keeping two small stacks accurate is easy. Keeping thirty bricks in a line accurate by eye is not, and every professional on every site does it the first way.
Amara Tell me about the bond itself.
Nadia Stretcher bond, which is what almost every modern outer skin is. Each course offset by half a brick, so every brick spans the joint below it.
Amara Why does the offset matter structurally?
Nadia Because a load coming down spreads sideways into the bricks either side instead of running straight down one continuous vertical joint. Line those joints up and you have a straight joint, which is much weaker and looks wrong the instant anybody glances at it.
Amara And how do I make the offset at the end of the wall?
Nadia A half bat. A brick cut in half across its length, starting every other course. That is what produces the stagger, and it is the first cut most people ever make.
Amara Any other bonds I should know?
Nadia Three worth recognising. English bond alternates whole courses of stretchers and headers, and it is very strong. Flemish alternates them within every course and it is the handsome one you see on Georgian houses. And English garden wall bond runs three or five stretcher courses to one header course, which uses fewer facing bricks. Which tells you exactly why it ended up on garden walls.
The written material
Why a brick is that size
A standard UK brick is 215mm long, 102.5mm wide and 65mm high. Those look like arbitrary numbers until you add a 10mm mortar joint, and then the system appears.
215 plus 10 gives 225, and two brick widths plus a joint, 102.5 plus 102.5 plus 10, also gives 215. That is what makes bonding possible: a brick laid across the wall is exactly as long as a brick laid along it. Height works the same way: 65 plus 10 gives 75, so four courses rise 300mm exactly. Everything in bricklaying comes back to those numbers.
The first course decides everything
Nothing you do later rescues a badly set out first course. Get the line, the level and the bond right at the bottom and the wall builds itself. Get them wrong and you will be cutting bricks and fudging joints all the way up.
Set out dry first. Lay the whole first course on the foundation without mortar, with 10mm gaps, and see where it lands. If you finish with an awkward 40mm gap at the end, adjust the joint widths very slightly across the whole run rather than cutting one horrible little slip at the corner.
Then build the ends first, several courses high, racking them back. Run a string line between them at the top of each course and fill in between. This is how every professional builds a straight wall, and it is far easier than trying to keep a whole long run level as you go.
- Check the foundation is level and the damp proof course is in place before the first brick
- Set the wall out dry to find the bond before mixing anything
- Build the corners or ends first, then run a line between them
- Check level along, plumb up, and gauge every few courses
Stretcher bond, and the half bat
Stretcher bond is a single skin wall, half a brick thick, with every course offset by half a brick. It is the bond on almost every modern cavity wall outer skin in the country.
The offset is the whole point. Each brick spans the joint below it, so a load is spread sideways into the bricks either side instead of running straight down one continuous vertical joint. A wall with aligned vertical joints, a straight joint, is significantly weaker and looks wrong immediately.
To create the offset at the end of a wall you start alternate courses with a half bat, a brick cut in half across its length. That is what produces the staggered pattern, and it is the first cut most learners make.
The other bonds worth knowing
English bond alternates a course of stretchers with a course of headers, bricks laid across the wall. It makes a solid one brick thick wall and is very strong, which is why it appears in older structural and engineering work.
Flemish bond alternates stretchers and headers within every single course. It is the handsome one, common in Georgian and Victorian domestic work.
English garden wall bond runs three or five courses of stretchers to one course of headers. It uses fewer facing bricks and less cutting, which is exactly why it was used on garden walls.
Stack bond has no offset at all and is purely decorative. It has almost no structural strength and needs reinforcement.
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