Developments in the Building Industry

Given the limited level of development within the National Park, advances in the new buildings technologies being used may be slow but we might expect further growth of interest in some areas where a national trend is already visible. For instance an increase in the use of timber frame buildings with high levels of thermal insulation has changed the nature of external wall design from structural mass to frame and skin and will raise the status of timber as a cladding material.

As a natural renewable material timber claims attention – we have after all a maturing forest product resource on the doorstep in Kielder Forest. However, it should be recognised that the character of timber design is different from building in stone and there may be difficulties of integrating one with the other. In this context the Park Authority will look to the best examples of timber building design in other areas of the North (particularly in Scotland) to widen its understanding of the technical issues, but proposals for timber framed and finished buildings will not be rejected simply on the ground that past buildings have been built in stone.

The other main area of change lies in the direction of man-made materials which now form an economic substitute for scarce or expensive natural materials.

The palette of materials in the traditional building is limited to stone, timber, slate, (clay pantiles as an alternative roofing material in the North end of the National Park) lead and glass.

The National Park Authority is in no doubt that natural stone which has for so long established the character of existing buildings in the Park should continue to be the principal material for new buildings too. Although the estate quarries have closed there are still sources of new building stone within easy reach of the Park (Blaxter, High Nick, Doddington, Swinton and Stainton). The Park Authority has accepted there are industrial and agricultural building types in which use of selected blockwork or artificial stone may be appropriate.

Similarly natural slate continues to be the Park Authority's normal requirement for roof coverings wherever slate is the existing traditional material. Sources of slate are not difficult to find but care must be exercised in selecting suitable colour and size if foreign sources are used.  Issues relating to the expense to the environment in moving materials around the world must also be considered.

In the north of the National Park the continued use of clay pantiles will be encouraged as a distinct local variation. But again manufactured sheet materials have been accepted on farm buildings throughout the Park and may be appropriate in certain circumstances on other building types.

The palette of new materials might be selectively extended to include large units of glass with structural and thermal properties, metals such as stainless steel, bronze and aluminium which perform much better in damp conditions than mild steel. Timber can be used in a far wider context since it can be engineered to extend its structural use and protected and finished in ways to allow its natural colour or grain to be shown.

Structural materials

Steel and other structural metals, reinforced concrete, and engineered timber allow much greater spans for openings in walls or for clear spans over useable space. If these are used to create longer openings, there will be an effect on the scale and proportion of the building, for example the impact of longer, shallower roofs and the greater mass of built form.

Roofing materials and technology

Generally existing roof coverings within the Park are slate (Welsh, Scottish, or Cumbrian) clay pantiles, lead sheet or profiled metal or fibrous cement sheet (mainly on agricultural or community buildings). These materials all depend on the pitch of a sloping roof for their performance. It seems to be the general experience that flat roofs covered in cheap bituminous felt are neither technically sound nor satisfactory in appearance, but flat and shallow pitched roofs do have a place in the contemporary development of the 'Green' roof, covered with turf or drought tolerant sedum in which high quality membrane is backed by effective thermal insulation and the green top protects the construction from variations of temperature and damage by ultra-violet light. Smaller flat roofs unsuitable for this kind of management can be hidden and protected by parapet walls but built up felts should still be protected against degradation by ultra violet light.

Openings in roofs may increase in size with the larger span glazed elements constituting a complete section of a sloping roof. Technical advances in glass production provide gains in structural strength as well as thermal performance. If such components are introduced provision must be made for access to clean external surfaces and to maintain the glass seal with surrounding materials. Glass used in lower roofs can make access to areas above them difficult and may be vulnerable to snow-slip from higher roofs.

Walls

As with roofs the National Park Authority recognises that walls must now perform tasks that the simple massive stone walls of the past did not set out to do.  Depending on the age of the existing building the stone wall provided security, fire-proofing, structural stability and protection from rain and wind: but it did not always prevent damp penetration or provide much thermal insulation – only a kind of levelling out of temperature and moisture content across the seasons.

The wall today performs (and must meet certain standards in performing) certain functions and designers have choices to make. Cavity construction, rain screen cladding, timber framing, curtain walling, double or triple glazing are all available but the balance between them must meet the even higher expectations of thermal insulation set out in Building Regulations. Much attention must also be given to jointing, sealants, and lapping to ensure water tightness and to control problems of condensation.  

Window Openings

Traditional windows were limited in size by the structural possibilities of the masonry wall and had painted timber frames usually with small panes of glass, themselves restricted in size by the glass production processes of the past. The essential character lies in the sense of the window as a 'hole in the wall' – the frame set back into the thickness of the masonry to protect it from the weather emphasising the shadow of the hole. The walls of older houses were thick enough for a deep embrasure inside too, often providing a window seat and with side reveals splayed to admit more light.

Windows set deep in stone walls emphasise the sculptural quality that can be achieved with masonry.

Today walls are not normally as thick so it may not be possible to achieve both these benefits. The National Park Authority will aim to encourage thought to the external sculptural quality of the contemporary building with windows cut into the solid form emphasised by shadow.

The National Park Authority accepts that householders building new dwellings may seek larger windows to allow more light in and a view out. Often the orientation of the main windows in a house will seek to take advantage of the low sun of winter months in the south elevation and the long evening light of summer in the west.  Windows in the east and north walls by contrast might reflect the idea of shelter from wind, wet and cold in that quarter.

With larger openings the frame, which will tend to be heavier in section, should be hidden as much as possible within the masonry surround. Sub-division of the glass need no longer mimic the small pane size, for with the emphasis on the thermal insulation performance of double glazing in windows it is no longer efficient to use small panes. Where it is difficult to incorporate framed glazed opening lights consideration might be given to the introduction of solid timber opening panels for use when ventilation is required, i.e. separating the inherently incompatible functions of shielding and ventilation.