Strong winds can prevent work at height, on roofs or with cranes, damage existing works and even collapse scaffolding. Rain, snow and hail will likely prevent progress on electrical works, cause access problems for heavy machinery, affect concreting and can cause flooding on poorly-drained sites.

Disruptions on the roads, at ports and on railways can cause delays for suppliers delivering goods to site or prevent staff from getting to site.

These delays can play havoc with a carefully coordinated construction programme, where (for example) a delay to installation of concrete foundations can have knock-on effects to the entire project supply chain (both materials and labour).

Under the construction contract, who is responsible for weather based delays?

The general rule is that if the contract is silent on weather delays then these will be the contractor’s responsibility. To counteract this, many contracts will identify adverse weather within the extension of time provisions as an employer risk event.

When un-amended, JCT Design & Build Contracts (both 2011 and 2016) place the risk of adverse weather on the employer. Both versions define exceptionally adverse weather conditions as a “Relevant Event” under the contract, which entitles the contractor to claim a fair and reasonable extension of time without penalty. However, in both JCT’s exceptionally adverse weather does not fall within the definition of “Relevant Matter”, so the contractor will be able to claim additional time to complete the works but will be unable to claim additional money from the employer.

The NEC contract does not distinguish between delay events, so the contractor will be able to make a claim for additional time to complete and also money to do so.

FIDIC Conditions of Contract for Construction for Building and Engineering Works uses the term exceptionally adverse climatic conditions, but again places the risk on the employer.

How bad does it have to be?

Whilst most construction contracts will use the term exceptionally adverse weather conditions (or similar), not all will accurately define it.

The NEC engineering contract refers in clause 60.1(13) to weather events which are shown to occur on average less frequently than once in ten years. This will be by reference to an established climate data source for a specified location (ideally one as close to site as possible).

The JCT contracts do not get any more specific than exceptionally adverse weather, but amended contracts seen within previous case law often refer to 10 years of previous meteorological records for the site as the frame of reference within which to argue.

In the absence of any specific provisions within the contract, a Met Office weather warning for weather conditions which are likely to cause delay (such as snow or wind) in the relevant area may well be sufficient, but this will depend on the attitude of each individual employer.

The general rule is that the key word within this phrase is ‘exceptionally’. Whilst snowfall in May would likely allow the contractor to claim an extension, snowfall in December would probably not.

How should I deal with adverse weather?

The key advice here falls into three categories: planning, notices and record-keeping. These could equally be referred to as before, during and after.

Programmes which are running through the depths of winter and the height of summer should make allowances for weather conditions accordingly. Processes which require certain temperature ranges should be timetabled accordingly, along with works requiring a dry period or soft ground through which trenches can be dug. This also affects works such as landscaping.

Your contract is likely to require the contractor to give notices to the employer if adverse weather (or anything else) is likely to cause a delay to project completion. The contractor should ensure that the notices are given in accordance with the timing and details required, to the people specified under the contract.

If adverse weather conditions do strike, records are very important. Photos from site, details of logistical issues (closed roads or difficult travelling conditions) and even video footage can help paint a picture of why the adverse weather caused a delay. The issues caused could include damage to existing works resulting from storms or flooding as well as severe weather preventing work on site or access to site. A weather station on-site will provide accurate data for the site itself, which removes the need for any estimation of wind speeds or amount of rain recorded. An email explaining that “the average site temperature of -2®C and the heavy snow from Monday 7th – Thursday 10th prevented the pouring of concrete, setting the entire programme back by four days and requiring additional payments for off-site storage of damp-proofing materials” will be far more likely to accepted by an employer than the assertion that “the cold weather in January delayed us by a week and increased our costs”.

If you have encountered any issues with adverse weather conditions or have any other construction related queries, feel free to contact me.