What Brick should you use for one course underground

[Kevinmwest]

I am having a conservatory fitted and I am in dispute with builder about using sand faced LBC brick for the first layer of brick that will be on the concrete base surrounded by slabs.

Should he do this as everyone I speak to including building regs seems to disagree.

The builder said that it is not a problem and should trust what he is saying as he is been in the business for over 25 years building houses, extensions.

I would appreciate some advise.

[thedoctor]

Presumably if this course (and we hope the one above it) are under the DPC if it is to be surrounded by slabs Kevin. The slabs must be at least 150mm (two courses) below DPC. The DPC will take care of any water wanting to rise in the bricks and from the point of view of the visual appearance the same bricks would look better. The regs do not dictate which materials to use in this case, only in foundations. A lot of people prefer to use engineering bricks on a slab for the first two courses under a DPC because of water splashing on them, from slabs, during a rainfall. If you read our project on freeze-thaw action this makes sense, but visually it may not suit you. As long as the water cannot get through the DPC its ok but this is only acceptable in a cavity wall situation. If your conservatory only has a single skin (100mm thick) wall then engineering bricks should be used but we would also question the suitability of such a structure. Take a look at most houses and you will see that the same bricks are used for the two courses of bricks under the DPC as are used above. Its only "In the ground" that different bricks, and blocks, should be used and this is most often on the basis of compressive strength or chemical ground activity rather than just plain damp conditions.

[bikertim]

I am a bricklayer and I would not advise using LBC bricks under the DPC you will have trouble in the future .The face will fall off due to frost,fact.Get some semi engineerings,you will find they are cheaper than LBC's anyway.