Dundonnell House is listed category B. It is a simple vernacular, symmetrical fronted house dated 1769, raised with pedimented dormer heads in 1816, at which date the interior was remodelled. The rear wing was altered in 1960 being raised to the same height as the front. Included in the listing is the Garden Cottage, a mid-19th century single-storey building incorporated within the garden walls, and the Ballroom built by the Rogers in the late 1950s to the south of the house. The Walled Garden is early 19th century and is listed B. The wrought-iron decorative gates were added by the present owners. Within the garden walls are several fine pieces of modern sculpture and garden ornamentation, acquired and brought to the garden since 1956. The buildings of Dundonnell are listed A as a group because they present an unusually complete example of a laird's house in the west of the Highlands.
The lawn provides a formal approach to the house. It is almost triangular in shape, tapering to a point at the south-easterly corner. At this point, a driveway indicated on the 1st edition OS map once existed; its former line is marked by the mature beech trees which remain near the lawns. Daffodils have naturalised across the lawn. A clump of mixed trees planted on the drive post-1945 have since been removed although the cedars have been retained. The house is now approached through a gate in the stone dyke north of the house.
The walled garden is situated on a flat site to the north of the house. The garden is indicated on the 1st edition OS map of c.1860 with a grid pattern of paths, most of which have been maintained although others have been added. The basic 19th century structure of the garden as one unit has been maintained but it has been divided into separate compartments by Alan Roger since 1955.
Entry to the garden is through a gate in the south-east wall adjacent to the house. The gate opens onto a gravel area where there are Yuccas and a Laburnum tree on which a Jacobite Rose (Rosa alba 'Maxima') has been trained. Opposite the gate, beyond the gravel, is the lawn, divided into two compartments by a double yew hedge and overshadowed by the central feature of the garden, a large mature yew, said to be the second oldest in Scotland. On the south-west lawn are unusual specimen trees including Salix matsudana 'Tortuosa', Larix lyalli and the particularly unusual Quercus pontica. The south-east lawn is more open, dominated by specimen bamboos. A good collection of bamboo varieties is grown throughout the garden.
A path leads from the gravel area around the outer edge of the garden, separated from the walls by borders which are contained by the original box hedging. The walls are lined with fruit trees and flowering shrubs including climbing roses and Buddleia. Beneath them grow a wealth of species of great botanical interest. The wall facing south-west is of particular interest all year round. Its border is 14m (40 yards) long and 3m (9 ft) deep. Flowering commences in May/June with pink and white colour provided by Kolkwitzia amabilis and Olearia macrodonta. Cytisus battandieri 'Pink Grootendorst' and Gladiolus byzantinus provide variation in the colour theme. As the season progresses, the colour and texture combinations change with the introduction of the flowers of Carpenteria californica and Calycanthus fertilis, culminating in the autumn season when late flowering Clematis line the walls with ground level interest maintained by Fuchsia sp.
At the junction of this border with the north-west wall are the greenhouses, one of which is an old Victorian cast-iron structure. All have been restored since 1955 and one is now partially heated. Inside, they are divided into three areas. Most of the plants grow directly into the ground; they include Iris wattii, Lapageria rosea, Berberidopsis corallina and Fuchsia arborescens as well as many ferns, Begonias and Pelargoniums.
Within the perimeter path are the smaller character gardens. The Bonsai Garden is the feature for which Dundonnell is perhaps most famous. The bonsai trees are arranged on shelves on a slatted wood enclosure which displays them to their best advantage. Beneath the shelves is a pebble garden where ferns and mosses are grown. The pond garden was established by Mr Roger on the site of a former rockery but many of the older shrubs were retained. New additions include Acer palmatum 'Senkaki' and three species of Stewartia. The Laburnum Tunnel is another fine feature of the garden. Vegetables and fruit are grown for the house, protected by netting from the peacocks. Some exotic birds are still kept in the aviaries which are situated in the western corner of the garden but the majority of what was an extensive collection of birds has now been given to Edinburgh Zoo. The Herb Garden, defined by vertical bamboo canes, was established on the area of the former drying green. Plants such as bay, woodruff, applemint and rue form the structure within which other plants have been established. The more unusual ones include Prunus mume, Elaeagnus commutata, Helichrysum splendidum, Rosa setipoda and Decaisnea fargesii.