Good start, what is the structural material? I like foam board, it's easy to get free from shops or supermarkets who use it for hanging signs, it is light and stronger than card on its own. Plasticard is good too, but more costly and trickier to cut.

Im yousing card however looking at clay for thin walls as it makes the 3d sence that card and foam find hard to provide i am also looking at the signs as they are out of scale with the model the roof and sides are going to consist of a brick layer at the bottom and a concrete layer fitted with windows the roof is virtuly the same concrete but not shown from the image it will be angled.Please keep resoponding thanks.

Clay adds too much weight to be supported by a single thickness of card, also it is wet when applied which makes the card warp. A mortar course in 4mm is less than .5mm in scale size so brick paper is perfectly acceptable, with a good range of colours and weathered options available to download and print. Most people seeking surface detail in brick use embossed plastic sheet. This is good, but allowance should be made for priming, usually with an acrylic aerosol can, which means no fitting window glazing or signs etc until finished painting.

Thanks for that i think i may have seen it at shows . but i still think it mite pull of when only used as small walls such as parking fences and farm yard bits.