How to fix into breeze block
Updated 19 September 2026 · 6 min read
Published by CAVE4MAN — storage, workshop and man-cave kit for UK home garages. The shop is not open yet.
Drill aerated breeze block without hammer action, using a sharp masonry bit at the size on the fixing packet, then use a fixing made for lightweight block rather than a standard plastic plug. Standard plugs crumble the block and pull out under load. For anything heavy, fix a timber batten on many fixings and hang the item from that.
Two very different blocks share one name
Breeze block is a name that gets used for two materials that behave nothing alike. The original breeze block was a dense block made with cinder aggregate, and the term now covers the dense grey concrete block used in garage walls and outbuildings. That block is hard, heavy and takes a plug much as brick does. The other material is aerated block: light, pale, full of tiny bubbles, and the one most people mean when they say thermalite.
Aerated block is the one this guide is about, because it is the one that catches people out. It was chosen for its insulation and its light weight, not for holding fixings, and it is common in the inner leaf of integral garages and in newer blockwork garages generally. You can push a screwdriver into it. You can cut it with a hand saw. A plug that relies on pushing outwards against something solid has nothing solid to push against.
Tell them apart with a drill or a nail. Dense block resists; a masonry bit on rotary only makes slow progress and throws hard grey dust. Aerated block gives way almost immediately and the dust is pale, fine and comes out in a soft stream. If a nail can be tapped in by hand with a light hammer, it is aerated and everything below applies.
Why the standard plug pulls out
A standard plastic plug holds by expansion. The screw forces the plug outwards against the wall of the hole, and the wall pushes back. In aerated block the wall of the hole does not push back; it crushes. The plug expands into a slightly larger hole, the screw feels tight for a moment, and the first real load, or the fiftieth small one, drags the whole assembly out with a cone of dust behind it.
It gets worse with hammer action. The hammer blows pulverise the block around the bit, so the finished hole is oversized before the plug has even gone in. Then the plug spins in the hole as the screw drives, chewing the block further. This is the sequence behind most of the fallen shelves in this material: an oversized hole, a plug that never gripped, and a screw that felt fine on the day.
Drilling aerated block properly
Turn the hammer action off. Rotary only, a sharp masonry bit, moderate speed, and let the bit cut rather than leaning on it. The block is soft enough that a good bit goes through on rotary without effort, and the result is a clean hole of the right size rather than a ragged one. The size is the one printed on the packet of whatever fixing you are using, not one up because the last plug spun.
Keep the drill square to the wall and do not wobble it to widen the hole. Drill a little deeper than the fixing is long, then clear the dust out with a blow or a vacuum before anything goes in; loose dust in the bottom stops a fixing seating and gives it something to slide on. A piece of tape on the bit as a depth mark costs nothing and stops you going through a thin inner leaf into a cavity.
Fixings that hold in aerated block
The fixings that work in this material all do the same thing in different ways: they spread the load over more block rather than trying to crush it. The table covers the common types. Every one of them is sold with its own drill size and screw specification on the packet, and those figures, not anything in this guide, are the ones to follow. The choice between them is mostly about how heavy the item is and how permanent you want the fixing to be.
Resin is the one to understand before dismissing it as overkill. A resin anchor does not expand at all; it bonds to the inside of the hole, so a crumbly material becomes an advantage rather than a problem, because the resin keys into it. It is the fixing to use when something genuinely heavy has to go on an aerated wall and a batten alone will not do. It is also permanent, so mark out carefully.
| Fixing | How it holds | Suits | Watch for |
|---|---|---|---|
| Long finned or helical plug for aerated block | A long plastic body with fins that bed into the block along its whole length | Hooks, small racks, light shelves | Needs the exact drill size; still a crush fit, so not for heavy hanging loads |
| Self-cutting aerated block anchor | A coarse metal or nylon thread screws into a pilot hole and cuts its own grip | Medium loads, repeat fixings, battens | Pilot size matters; overtightening strips the thread it just cut |
| Resin anchor with mesh sleeve | Resin fills the sleeve and bonds to the block; the stud sets in the resin | The heaviest items you would put on this wall | Curing time; a wet or dusty hole ruins the bond; it is permanent |
| Long frame fixing | Long plug and screw as one unit, driven deep into the block | Battens, rails, panels | Weaker in aerated than in dense block; use plenty and use them long |
| Timber batten on many fixings | Shares one load across a row of fixings, none of them heavily loaded | Anything heavy, or anything you will rearrange | Batten must be straight and fixed at close, regular spacing |
Spread the load and stop asking one fixing to be a hero
In dense masonry, one good fixing can carry a hook. In aerated block, the strategy changes: use more fixings, each carrying less, and let a piece of timber or a steel panel distribute the load between them. A batten screwed to the wall on a row of aerated-block fixings, with the hooks and racks screwed into the batten, is the method that turns this material from a problem into a wall you can use like any other.
It also suits the way garage walls actually get used. Hooks move. The parts rack that made sense next to the door turns out to belong by the bench. Into aerated block, every change of mind is a new set of holes in a material that does not forgive them. Into a batten, it is a woodscrew. The ten-pack of steel hooks, the four-tier tool shelf and the pegboard power tool rack are all happier on timber here than in the block itself.
Common questions
- Why do my wall plugs keep pulling out of breeze block?
- Because the block is aerated and a standard plug relies on expansion against a solid hole wall. Aerated block crushes instead of pushing back, so the plug expands into a slightly bigger hole and never grips. Hammer drilling makes it worse by oversizing the hole. Use a fixing made for lightweight block, drill on rotary only, and put heavy items on a batten.
- Can you use a hammer drill on thermalite blocks?
- You can, but you should not. The hammer action pulverises the soft block around the bit and leaves an oversized, ragged hole that no fixing grips well. Switch the hammer off and drill on rotary only with a sharp masonry bit. The block is soft enough that this is effortless, and the hole comes out at the size the fixing packet asked for.
- What is the strongest fixing for aerated concrete block?
- For a single fixing, a resin anchor: it bonds to the block rather than expanding against it, so the softness of the material stops being a weakness. For most garage jobs a timber batten on a row of aerated-block fixings is the better answer, because it spreads the load across many points and lets you move hooks later without new holes.
- How much weight can a breeze block wall hold?
- There is no single figure, and be suspicious of anyone who gives one. It depends on whether the block is dense or aerated, how thick the wall is, the fixing type, the depth it reaches, and whether the load hangs or sits. Aerated block on standard plugs holds very little. On purpose-made fixings or a batten it will carry ordinary garage storage without trouble.