The need to incorporate the appropriate ceiling height to achieve the 'correct look' for the design of the home would be apparent to most people.- A replication of a 'Victorian' or 'Edwardian' style requires a high ceiling height to enable a duplication of the features of that era and at the other end of the scale a 'log cabin' design would be more suited to a low ceiling height to emphasise the feel of that particular design.
Ceiling heights have traditionally been from 3 met. (10 ft.) to 3.6 met. (12 ft.) for homes prior to the 1950's and into the 60's, down to 2.4 met. (8 ft.) for many designs throughout the 70's into the 80's and early 90's.
The preference currently tends to be for 2.7 met. ceiling levels. In addition to creating a more open feeling to a home against the possibly more economical 2.4 met ceilings that were common earlier, this higher ceiling level enables clearance for ceiling fans - which are an excellent item for circulating air for heating and cooling - and permits more design flexibility, in for example the use of taller feature windows and doors.
To give an indication, the difference between a ceiling height of 2.4 met. and 2.7 met. equates to an increase of 12.5% in both internal and external wall stud heights; the lining material to both sides of the internal walls; the internal lining and external skin of exterior walls plus any insulation.
A home with a 2.4 ceiling height, a normal roof slope of around 27 degrees and standard 450mm eaves would result in the eaves lining being directly on top of the window head as shown below.
A 2.7 ceiling level would require an infill [ of 300mm ] over the windows, typically in weather boards or brick.
(Brick lining requires the addition of steel lintels over the openings.)
This is not a major cost, but as can be seen it does have an influence the outside appearance of the home.
In some situations on reactive soil sites, vertical control joints are required to lessen cracking in brickwork due to foundation movement. Typically full height window locations would be used to serve as a 'breaking' of the panels to achieve the requirement. With higher ceiling levels timber infills may be employed above the windows to continue the break in the brickwork. In the situation where the brickwork is continuous over the windows, a straight vertical joint may needed in the panel from the window head to the eaves.
Possibly the biggest area where ceiling heights can impact on the exterior of the home is in relation to the design of verandahs.
Building regulations require a clearance of approximately 2100mm from the underside of the verandah beam to the decking level or ground level as the case may be.
Using an example of a 2400 ceiling level; a 27 degree roof slope with a single step down from the house, shows that to achieve a 1.8 met. wide verandah, that our verandah roof slope would have to be altered to approximately 14 degrees to conform with regulations. - creating a 'bell roof' effect.
A ceiling height of 2700 would enable us to incorporate a 22 degree pitch to our verandah.
A 'homestead' style design with a typical 17 degree pitch in conjunction with a 2700 ceiling level would enable a 2400 wide verandah under the existing roof slope. [ no bell ]
It can be seen that those wishing to include wider verandahs or to lower ceiling heights to meet a budget can be faced with several design restrictions.
There is the option - more so with stump and timber floor construction - to have several steps down from the house floor level to the deck level. [Building regulations require that with more than 3 steps - 570mm - a handrail must be installed.]
In most cases more than one step down is not a design option for many people.