A step by step guide on how to laying walling blocks including tools required and tips for success from our friends over at Bradstone.
All walls, whatever the height, need to be built on a firm foundation. This might be an existing concrete base or for a ‘dwarf’ wall (a wall less than 600mm high) on top of an existing paved area.
Important: If you plan to build a retaining wall higher than 600mm or for any wall over 900mm, we recommend that you use an experienced professional
Tools you will need:
- A pair of trowels and a pointing bar
- String building line
- Long spirit level
- Rubber mallet
- Length of timber
- Spade/tools for digging out
- Club hammer and bolster chisel
- All-in ballast, building and sharp sand is available from Capelles will be able to advise quantities.
Ensure you are wearing appropriate safety protection throughout your task. Wet mortar can burn exposed skin, so make sure you’re wearing suitable protective gloves and long sleeves to protect your arms.
STEP 1: Digging out the foundation
Mark out the line and position of the wall and then dig out for the foundations.
For dwarf walls, the foundation will need to be 150mm thick and wide enough for the walling blocks and an additional 100mm spread either side.
The finished foundation should be at least 50mm below ground level.
STEP 2: Laying the foundation
Lay level concrete foundations using 6 parts all in ballast to 1 part cement.
Mix the ballast and cement and then add water. You need a fairly wet, pourable concrete so that it flows into the trench footing and is easy to level out.
Simply pour the concrete into the trench, spread out and then tamp down with a length of timber to expel any air pockets that might have formed. This creates a rough, rugged finish that will be an ideal base for the mortar.
Use a long spirit level to ensure the concrete is flat with no slope or fall in any direction.
Leave the concrete over night to give it chance to harden before you move to step 3.
STEP 3: Setting the string level
Start by dry laying the first course of blocks out to check where they will sit on the footing and whether you will need to cut any blocks to fit.
Then move the blocks out of the way and set up a taut string line. This acts as a guide to both the alignment and level of the first course of walling blocks.
Set the height so that it is level with the top of the blocks and make sure you use a spirit level to check it is flat with no fall or slope.
STEP 4: Preparing the mortar
For wall building you need a brick laying mortar of 3 to 1 mix. That’s 3 parts building sand to 1 part cement.
Mix together with a little plasticizer to make the mix more workable. Add just enough water to make a smooth and pliable mortar that is easy to spread.
It needs to be stiff enough to support the weight of the walling block, but soft enough to allow you to work with it and settle the blocks onto it.
STEP 5: Building the first course
First make the mortar bed. Place a line of mortar onto the concrete footing and ripple it with the point of the trowel to make sure there is enough ‘give’ when you set the block onto it.
Put enough mortar on the footing for the block you are laying with a little extra to ensure the end of the block is fully supported.
Place the block into position and using the rubber mallet gently tap the block down to the correct height set by the string line.
Although the string line should be a good guide, double check your levels using the spirit level. Then it’s on to the next block.
The mortar should slightly exude from between the joints and any surplus should be cut off with the trowel.
Remember to fill the vertical joints by applying mortar to one end of the block before positioning it adjacent to the previously laid block.
Keep checking your levels – you can never do this too often!
STEP 6: Building the wall
Stagger the blocks on the next course to ensure the vertical joints don’t coincide.
Where there are gaps of less than a block’s width, you will need to cut a block. We recommend you use a club hammer and a sharp bolster chisel.
Ensure you have marked the block carefully before you cut it.
STEP 7: Pointing the joints
Use a pointing trowel to smooth off the mortar that has been squeezed out as well as filling the gaps
STEP 8: Adding coping stones
If you’re adding coping stones to the top of the wall, then plan the joints you need to avoid vertical joints coinciding, allowing a 10mm joint gap between each coping stone.
If you’re using flat coping stones, ensure there is an overhang both along the long face and the short end.
Then lay following the same steps as the walling blocks.
Remember to keep using your spirit level to check the levels and add a slight fall towards the front edge so that the rainwater will run off.
That’s job done – as a quick reminder follow our 3 tips for success to create a dwarf wall.
- Make sure the foundations are level and solid
- Check your levels frequently with your spirit level
- Never build more than 6 courses at a time.
Why not download the Bradstone Laying Walling Blocks Guide to take on site: