Parapet walls for hothouses

2103. The parapet, or front wall, of hothouses comes first in order. Where upright sashes are used, there are generally brick walls, either carried up solid from the foundation, or built on piers, according as it may be desirable to have the roots of the plants within pass through to the soil without, or not. In the case of fixed roofs, that part of the wall which is above ground is formed with horizontal openings, to which opaque or glazed shutters are fixed, opening outwards, for the purpose of admitting air.