Class A engineering bricks

[flanagaj]

So I'm going to purchase some engineering bricks for below ground and for a couple of courses that will be behind the wood cladding.  What I'm struggling to understand is why you'd pay £1.50 for some class A glazed, when a 22N concrete brick is £0.50?

[Oz07]

Just if they're on show I think. How much is a class b red engineering brick nowadays? Used to be about 20 pence. 

[flanagaj]

53 minutes ago, Oz07 said:

Just if they're on show I think. How much is a class b red engineering brick nowadays? Used to be about 20 pence. 

They seem to vary widely.

 

https://materialsmarket.com/building-materials/bricks-blocks/engineering-bricks

[Russell griffiths]

Why do you want class A , class B is standard for domestic. 

[Gus Potter]

On 22/02/2026 at 19:24, flanagaj said:

So I'm going to purchase some engineering bricks for below ground and for a couple of courses that will be behind the wood cladding.  What I'm struggling to understand is why you'd pay £1.50 for some class A glazed, when a 22N concrete brick is £0.50?

Ah you have opened up a topic that for the techy minded,  can be a world of fun and no fun for most of the general population. 

 

36 minutes ago, Russell griffiths said:

Why do you want class A , class B is standard for domestic. 

Agree and generally true but.. and is likely in your case. Engineering bricks are selected from time to time for their strength, not just in compression but also for their ability to enhance the lateral strength of a wall, often when subject to wind. When combined with a higher strength mortar they can be a cost effective option. On most domestic applications a Class B is adequate strength wise. Class A's are so strong that often you find it's the other bits a round them that are weaker by a mile.

 

But another thing about Engineering bricks is that they have a low water absorption. This matters particularly when we live in Ireland / Scotland as we want a brick that is not going to be attacked by frost, we call this the durability.

 

@flanagaj my instinct tells me that a class B brick will be ok unless there is some reason not to use this. Just ask your SE as the bricks are protected by timber cladding to some extent as you well say. You also have DPC's etc. 

 

OK where would I consider using Class A Engineering brick?

 

SE wise where I need to do something really bespoke and are looking for pure strength (compression and lateral strength) and want to spread point loads.. much like a big padstone. Can't recollect if I've ever done this.. as above due to the other elements often failing long before.

 

But where I have done it is on refurbishments of old stone barns / stone tenement works etc. These often have no damp course. I usually use class B engineering brick as a few course of this acts as a DPC. In very wet places where there is a space constraint (often in foundation underpinning) I may use a class A, as you need less courses to act as a damp course. 

 

Now to circle back.

 

On old buildings the walls can be often over the limit for what we call slender. In other words the ratio of it's height to thickness can be beyond the modern design codes. The last thing we want to do is to introduce a plastic DPC at the base of the wall as this creates a rocker bearing which can be very dangerous. By using an engineering brick as a DPC we get around this problem. There are thousands of traditional buildings all over the UK that use this method. You do, from time to time have to make a note on your drawings for building control so they know what you are doing and why.