Module 11: Maintenance and Design


1. Comfort, sound insulation and resilience 
2. Overheating 
3. Pitched roof insulation 
4. Flat roof insulation 
5. Internal solid wall insulation 
6. External solid wall insulation 
7. Timber framed wall insulation 
8. Suspended floor insulation 
9. Air tightness and the use of tapes 
10. Use of vapour control membranes 
11. Maintenance and design
12. Choosing the right systems

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With new construction materials comes the ability to build in new and exciting ways. However, traditional principles still apply if you want to create low maintenance, durable buildings that will last many years.

Simple design

Simplicity is key in building design and construction. This allows very high construction standards and high performance but also creates buildings that are low maintenance and less likely to have problems. It can also create buildings that are easy to adapt to the future needs of occupants, an important consideration for the longevity of our buildings.

Simple design can mean many things but here we are looking at form and also construction methods. Simple, solid walled or monolithic construction is inherently easy to build, resulting in buildings which perform well and that are attractive spaces in which to inhabit. Buildings that perform well will inevitably have a long lifespan as there is no need to replace them.

Simple form that retains classic rather than over stylised features will not date so fast. Fashions change quickly relative to the lifespan of a building and highly fashionable buildings from one period can be deeply un-fashionable in the next.


One thing often missing from modern architecture is the roof overhang. Similarly, the cubist style sometimes used requires as little overhang on parapet walls as possible. Whilst both can look very striking once construction is complete, surface finishes can deteriorate quickly and spoil the appearance of the building.

Good eaves and gable overhangs can make a huge difference to the rate at which surface finishes, such as render or cladding, degrades or becomes stained by algae. Horizontal or low gradient surfaces accumulate bird droppings and algae which is then washed on the wall surfaces by rain. The larger the overhang the less likely this is to happen.

There is a very Devonian phrase which says that ‘a house is like a baby, it needs a good hat and a dry bottom’. This is somewhat vernacular but is a good rule of thumb for long lasting construction. Larger roof overhangs protect facades but also give shading from strong sunshine during the summer.

The ‘dry bottom’ refers to having a good foundation that is high enough above ground level and splash zones to prevent moisture ingress into any moisture susceptible materials, such as timber (or the cob local vernacular).

Robust finishes

It might seem obvious but spending a little more on the finishes used on a facade can have a massive effect on the reducing the maintenance cost of a building. There are render systems available to suit all construction budgets however, the maintenance requirements vary enormously between them, affecting long term cost and viability of the building.

Basic cement based renders with acrylic finishes are the main stay for speculative construction as they are cheap and will look as good as any other render system for a few years. However, their lack of stain resistance and propensity to grow algae ensures that they need regular cleaning and re-decorating, pushing up the lifetime cost enormously.

The slightly more expensive lime based renders and nano-porous silicate or extremely hydrophobic silicone finish renders are more flexible, breathable and are very stain resistant. The long periods between cleaning or redecorating ensure that although the initial cost is slightly higher, the lifetime cost of the systems is the lowest possible.

Timber facades can be provide beautiful finishes too but again, choosing long lasting, durable finishes over cheaper materials which will discolour and decay quickly will have a beneficial effect on reducing the lifetime cost.

Timber is often used with shadow gaps between the boards to provide a more striking architectural appearance. These gaps allow sunlight to penetrate the facade and the breathable facade membranes used behind them are only guaranteed for 15 years. If this is similar in length to the lifespan of the timber rain screen then it can be replaced at the same time. However, if that is not the case, the ability to remain water-tight may be lost before the facade needs replacing, which may result in failures.

Maintaining your building

It seems that the more low energy your building is, the more part of the environment it becomes. Unfortunately all the additional wildlife that wants to live on your building brings with it some basic maintenance.

Surface maintenance of roofs is fairly standard and similar for most buildings. The shallower the pitch of the roof, the more important it is to check that the surface drainage is kept clear and flowing and that there is no damage. Roof lights should be opened regularly to prevent cobwebs and leaves from blocking drainage and the glass cleaned. It will also ensure any leaks are picked up before they become an issue.

Gutters and downpipes should be kept free of debris, vitally important if your design features concealed gutters or gutters behind parapet walls.

Facades should be cleaned regularly to ensure surfaces stay clear of dust, dirt and bird droppings. Rendered facades can usually be cleaned with some gentle pressure washing (from a distance of no less than 250mm) but in sheltered, northerly locations or under trees they may need additional fungicidal washes to keep clear of algae. Timber facades may need oiling or staining to maintain their aesthetic appearance or durability.

Windows need to be kept clean but high performance, triple glazed windows, particularly inward opening windows, need a little more care. Drains/weeps should be kept clear as some insects, particularly masonry bees, like to set up home inside them, causing water to accumulate and possibly drain inwards. They also have the annoying habit of hollowing out the insulation within the window to make their nests.

The seals on these windows will also need regular cleaning as the narrow channels and crevices they form make ideal homes for spiders. Their webs and leftover food can prevent the seals closing effectively, reducing airtightness but also blocking drains.

The plinth area should be checked regularly for any damage as this area receives a lot of wear and tear in most buildings. Splash back from rain and impact from just about anything you can think of tends to happen in this area. Any surface or stone drains should be kept clear of leaves and debris and any scratches or holes should be touched up with more finish render. This can usually be achieved by simply stirring up the render and dabbing/stippling it on to the blemish with a paint brush For some reason scratches in the surface allow the growth of algae on an otherwise unblemished wall as per the below photo.

Building maintenance has largely dropped out of modern life but a few hours a year spent looking after your home increases your sense of ownership, your sense of home and enables your building to perform at its peak.

Module Exam