Face brick water absorption below DPC advice required

[ruggers]

Could someone advise on the best type of brick to use below DPC on a house. I need to select a black brick for 3 courses below DPC, 1 course will be under the side path level and the other two courses will be above finish ground level. Some searches say 4.5% and others say 7.5% water absorption.

 

I was recommended the following brick which is 12% absorption, and is F2 S2.

My facing bricks above DPC are <10% and F2 S2.

 

[HughF]

Staffordshire blue/black engineering brick… Should be just fine. I don’t like non-engineering bricks below DPC although it has been done like that for decades.

[Russell griffiths]

As above, Staffordshire blues, order them and move on to the next problem, anymore than two minutes thought on this is overthinking. 

Only one product suitable for down there. 

Obviously different manufactures might have colour variation. 

[Dave Jones]

yep, engineering brick the colour you want. You could also use a block and have a vertical DPC on sloping ground.

[ruggers]

On 27/01/2023 at 10:26, Russell griffiths said:

Only one product suitable for down there. 

Obviously different manufactures might have colour variation. 

This is the only small problem, I asked the person who sources the bricks at competitive rates for our local merchants for a certain amount of engineering bricks like staff blues from a brand that is close to the amount i require, so I'm not buying packs and having hundreds spare and they came back with the the above brick saying as long as they're S2 F2 they're all suitable. I think I need around 900.

 

The light grey brick I chose for the house is F2 S2 and 10% but I can tell it would be crap if used below DPC so I just wondered if theres more to it. A Staff blue you can tell just holding it.

[Mr Punter]

Another vote for the Staffies.  Also good for padstones, lintel bearings, manholes etc.  About £1 each.

[ruggers]

Thanks, I'll just stick with the staffs I think, that was my original choice in smooth until offered the ones in the original post. You know they've been tried and tested.

 

[Drew1000]

Yes another vote for engineering brick.. Only solution in my opinion

 

[Temp]

I also vote for engineering bricks but..

 

https://nhbc-standards.co.uk/5-substructure-ground-floors-drainage-and-basements/5-1-substructure-and-ground-bearing-floors/5-1-13-durability/

 

Quote

 

5.1.13 Durability

 

Substructure and walls below the DPC shall be capable of supporting their intended loads and, where necessary, be resistant to frost action, sulfates and other harmful or toxic materials. Issues to be taken into account include:brickworkblockwork.

 

Frost damage occurs on saturated masonry exposed to freezing conditions. Bricks, blocks and mortars located 150mm above and below ground level are the most likely to be damaged by frost.

 

Masonry walls below the DPC should be designed and constructed as described in Chapter 6.1 ‘External Masonry Walls’.

 

Recommendations for the design strength of bricks, masonry blocks and mortars are given in BS EN 1996-1-1.

 

Brickwork

 

Bricks should be of suitable durability, especially in the outer leaf below the DPC, or where they could be frozen when saturated. Bricks used in retaining walls should be suitable for the exposure and climate, as recommended by the manufacturer.

 

Clay bricks should comply with BS EN 771, which classifies bricks according to their durability designation (F) and to the content of active soluble salts (S).

 

F0 Not freeze/thaw resistant and should not be used externally

F1 Moderately freeze/thaw resistant

F2 Freeze/thaw resistant

S1 Normal active soluble salts

S2 Low active soluble salts

 

Generally, bricks are designated to F1,S2 or F1,S1. If in doubt as to suitability, bricks of F2,S2 or F2,S1 should be specified,.... 

 

Continues