What Unforeseen Factors Can Increase my Home Renovation Budget?

Many clients fear the risk of unplanned cost increases. Investigation at design stage, and careful selection of a proper building contract reduces this risk.

In general terms, there is very little scope for a budget to escalate at construction stage once you have listed everything you want, and decided on a level of specification for the project when briefing your architect for the “technical design”. Standard rates of construction will apply to the majority of house extension schemes, with the exception of features which will be supplied by specialist sub contractors; such as special glazing.

The risks of increases usually come from the introduction of unknown factors:

1. Opening up of old structures and uncovering damaged parts of the building that need replacement
2. Digging foundation excavations for basements and discovering bedrock or obstructions which must be removed
3. Discovering dampness, insect damage or other issues during a detailed survey of existing structures
4. Discovering asbestos or other hazardous materials in existing structures which must be moved or removed to facilitate new works (I always recommend a specialist asbestos survey before buying any pre-1980 house.)
5. Economic changes to the price of labour or construction materials (where such changes may impact on price certainty under the type of building contract in place.)

Do any of these apply to your design?

I must say that I have not encountered any major expenses of this type in the last five years (2009- 2014) which were not flagged at the time of the initial survey, and for most extensions to houses built and architect- certified in the last 30 years such unforeseen circumstances are unlikely.

For works to protected structures, modern houses which were not properly inspected during construction, and houses which may contain asbestos, such issues are far more likely. An architect can investigate such issues by means of:

1. A thorough survey
2. Opening up of concealed spaces (by a qualified individual) as part of the design and project planning process
3. Using an appropriate form of contract to limit exposure to fluctuations in the cost of materials and labour.

Many clients fear the risk of unplanned cost increases. Investigation at design stage, and careful selection of a proper building contract reduces this risk.