I have just had an orangery built and a large number of the bricks are white in colour and it doesn't look good.

Hi, this is salt content seeping out of brickwork, usaully appears where water is either passing through the wall from the back, which means you a weep hole, or the top of the wall is letting in water. You can improve the salt staining by pouring hot water from a kettle over the staining and scrubbing with a wire brush. don't know what kind of brick you have, have may have to go carefully so as to not damage the brick face. This is a common problem that if left will crystalise and then be impossible to remove, replacing bricks would then be the only way. Keeping the water from penetrating the top of the wall is the best practice. Hope this helps you with your problem. Kind regards Paul

If it was built in freezing weather then this in itself is bad practice,as paul above has said it is efforvecent salts coming through which is a reaction with certain sands and bricks together,rub your mortar joints with your finger ,if they are crumbly not hard then frost has probably penetrated the mix in which case builder is right to offer re-build solution as if frost has penetrated through the wall has no strength,brickworks cement works ect should not be carried out under 5 degrees ,also they should be covered up after days work to keep frost out at night

this a very common thing with some new brickwork. like is mentioned above, its just the natural salts in the bricks themselves. basically when the bricks get wet they act like a sponge, then the salts are drawn out onto the outside surface where they dry into a white powder. i would recomend using a jet washer on the wall to get rid of it. trouble is its harder to get off that it looks. i once used brick acid thinking it would work, but it didnt touch it. like i say have a go with jet wash. might be a case of having to do once or twice a year for some time until the salts leeched out from the bricks. no reason to replace bricks at all. will only happen again with new bricks. i think the builder who told you that is just after some money from you for the job.

On the above comment, Check carefully on the joints between bricks for cracks and damage. If it was laid in the frost then the joints between the bricks may be powdery looking and flaking. If this is so be careful jet washing not to blow the pointing out....