Brick Trowels: Patterns, Sizes, and How to Use One Properly

Your mortar falls off the blade before you reach the wall. You try again, loading more, and this time half of it lands on your boots. The bed joint comes out uneven, the block sits crooked, and you've wasted twenty minutes and a barrow of mix on three blocks. This is the universal beginner experience with a brick trowel, and it's almost always a combination of wrong tool and wrong technique. Both are fixable.

What it is and when you need one

A brick trowel is a flat, pointed metal blade fixed to a handle, used for scooping mortar from a board and spreading it onto bricks or blocks. It's the primary tool for any bricklaying or blockwork. The blade is made from carbon steel, ground thin enough to flex slightly when you press mortar into a joint, but stiff enough to carry a full load without drooping.

The blade shape is an elongated triangle, wider at the heel (the end nearest the handle) and tapering to a point. That point lets you work mortar into tight joints and scrape excess away. The heel scoops mortar from the board. Everything about the shape serves the same two-stroke motion: scoop, spread, scoop, spread.

If your extension project involves any blockwork (and it almost certainly does, since the inner leaf of cavity walls and internal partitions are built from concrete blocks), you'll need a brick trowel. Even if your builder does the blockwork, a trowel is useful for patching mortar joints, setting out lines, and cleaning up during snagging.

Patterns: London, Philadelphia, and Wide London

Three blade patterns dominate the UK market. The names refer to the shape of the heel, and the difference matters more than most beginners realise.

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London pattern has a rounded heel and a narrow blade. It's the traditional UK bricklayer's choice for facework (the visible outer skin of a wall). The narrow blade gives precise control over mortar placement, which matters when every joint is on show. One edge is slightly curved for cutting bricks, the other is straight for picking up mortar. Professional bricklayers who lay thousands of face bricks a week tend to favour London trowels because the narrow blade forces cleaner technique.

Philadelphia pattern has a square heel and a wider blade. The square heel scoops more mortar per load, which speeds up blockwork where you're spreading thicker bed joints across bigger surfaces. It's less precise than a London for neat face joints, but for concrete blockwork on an extension, precision to that degree isn't needed because the blocks get plastered over.

Wide London splits the difference. Broader than a standard London at the heel, it handles both brick and block work reasonably well. It's the all-rounder, and if you're buying one trowel for occasional use on a domestic project, this or the Philadelphia is where to start.

How to use it properly

This is the section that every other trowel guide skips. Buying the right trowel is straightforward. Using it well takes practice, but understanding the technique before you start prevents the worst beginner mistakes.

Loading the trowel

Stand parallel to the mortar board with the board at waist height. Slide the trowel blade flat across the top of the mortar heap, scooping a sausage-shaped load along the full length of the blade. The motion is a smooth, flat slide, not a dig. You're skimming mortar off the top, not mining into the pile.

The mortar should sit along the blade in an even line. If it clumps at the heel or slides off the point, the mix is either too wet (sloppy, won't hold shape) or too dry (crumbly, won't stick). Properly mixed mortar holds its shape on the blade without slipping. If you can turn the loaded trowel upside down and the mortar stays put for a second before dropping, the consistency is right.

Spreading the bed joint

Flip the loaded trowel over in one smooth motion and spread the mortar along the top of the previous course (or the foundation) in a single pass. You're aiming for a bed of mortar roughly 15-20mm thick and wide enough to cover the block or brick width.

After spreading, draw the point of the trowel down the centre of the mortar bed to create a shallow furrow. This furrow helps the next course settle evenly and squeezes mortar into the perpend joints (the vertical joints between blocks). Don't dig a deep channel. A shallow V-shape, about 5mm deep, is all you need.

Buttering the perpend joint

Before placing each brick or block, spread mortar on one end (the perpend face). Three firm swipes: one on each side and one across the top. The mortar should be thick enough that it squeezes out slightly when the block is pressed into position. Squeeze-out means a full joint. No squeeze-out means a gap, and gaps let moisture in.

Placing and levelling

Press the block firmly into the bed joint, pushing it down and sideways against the previous block. Check level with a spirit level. If the block is sitting high, tap it down with the heel of the trowel handle (some trowels have a hard end cap designed for exactly this) or the heel of your hand.

Don't tap blocks down with the blade of the trowel. The blade is ground thin for flexibility, and striking blocks with it dents the edge and eventually cracks the steel.

Cutting excess mortar

As you press each block into position, mortar squeezes out from the bed and perpend joints. Slice this excess off with a single smooth stroke of the trowel blade, running along the face of the wall. Scoop the excess back onto the board or flick it back onto the mortar heap. Clean cuts keep the wall face tidy and reduce pointing work later.

Looking after your trowel

Dried mortar on the blade ruins your next session. Mortar sets within hours, and once it's hardened on the steel it creates a rough surface that stops fresh mortar from sliding cleanly. Every time you finish work, scrape the blade clean and rinse it with water. Takes thirty seconds. Skip it once and you'll spend ten minutes chipping dried cement off with a bolster.

A light coat of linseed oil or WD-40 on the blade after cleaning prevents rust spots. Store the trowel somewhere dry. Carbon steel rusts faster than you'd expect if left in a damp shed.

Replace the trowel when the blade thins noticeably at the edges (it wears down from scraping against masonry), when the handle develops a wobble, or when the blade won't hold its shape under load. A worn trowel makes consistent joints nearly impossible. Brands like Marshalltown and Ragni hold their shape significantly longer than budget alternatives because the steel is harder and the forging is better quality.

What to buy

Three clear tiers in the UK market, with real differences between them.

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The honest answer for most homeowners: buy a Ragni 10-inch Philadelphia at around £16 or an OX Pro at around £31. The Ragni is good enough for laying a dozen courses of blockwork and won't punish your wrist. The OX Pro is what you'd buy if you planned to use it regularly or wanted something that lasts years without maintenance worries.

Marshalltown is the professional's unanimous choice. Every UK trade forum thread about brick trowels ends with the same conclusion: "All the money-making site bricklayers I know use Marshalltown." At £50 it's not an absurd price for a tool you'll keep for decades, but it's hard to justify for occasional homeowner use unless you genuinely enjoy the work. If you want to try one, the 10-inch Philadelphia DuraSoft (model M1910D) is the one to buy.

Left-handed trowels

London-pattern trowels are not symmetrical. The cutting edge is on one side, which makes them handed. If you're left-handed and buying a London, you need a left-handed version. WHS and specialist suppliers stock them, but they're not always on the shelf at Screwfix or Toolstation.

Philadelphia and Wide London patterns are symmetrical, so handedness doesn't apply. Another reason the Philadelphia is the safer default choice for beginners.

Common beginner mistakes

Loading too much mortar. A full trowel load on a 10-inch blade is enough for one block-length bed joint. Beginners pile on a mountain and lose half of it between the board and the wall. Start with half-loads until the scooping motion feels natural.

Mortar too wet or too dry. If the mortar slumps off the trowel, it's too wet. If it crumbles and won't stick, it's too dry. Adjust at the mixing stage, not on the wall. Add water in small amounts and mix thoroughly each time.

Not cleaning the trowel during work. Mortar builds up on the blade as you work. Every ten minutes or so, scrape the blade clean against the edge of the mortar board. A clean blade picks up and releases mortar smoothly. A clogged blade doesn't.

Tapping blocks with the blade edge. Use the trowel handle, a rubber mallet, or the heel of your hand to adjust block position. The blade is a precision tool, not a hammer. Striking block edges with the blade chips the steel and creates burrs that catch on mortar.

Overworking mortar. Once mortar starts to stiffen on the board, the temptation is to add water and remix. This weakens the mortar. If it's starting to go off, scrape it aside and mix a fresh batch. Small batches are better than big ones, especially in warm weather.

Where you'll need this

Brick trowels appear across several phases of any extension or renovation project:

• Walls and blockwork - the primary use, laying both the inner blockwork leaf and any external brickwork
• Foundations and footings - bedding the first course of blocks onto the foundation, setting datum points
• First fix electrics - marking chase positions on blockwork before cutting
• First fix plumbing - marking pipe routes and penetration points
• Kitchen installation - minor mortar repairs, fitting adjustments
• Snagging checklist - checking joint quality and consistency across finished brickwork