If by a "double nave for a ceiling" you mean something like ˆ ˆ I'm told that early Welsh churches were / \ / \ not very sophisticated architecturally and / \/ \ tended to resemble large sheds. The easiest | | way to enlarge a shed to cope with a bigger | | congregation is to stick another shed on the side and knock down the common wall, leaving bits to act as pillars and hold up the roof. It seems to me that you would also need to pay a bit of attention to the (ecclesiasitical) East end to make sure it was central to the new layout - do the churches you looked at have a chancel of later date, possibly another smaller "shed" stuck on the end ? After all, Lego has to derive its inspiration from somewhere ;-) Or does one side of the nave culminate in a Lady Chapel ? Fran