Mould is a type of fungus that can be found almost everywhere as it makes up about 25 percent of the biomass on Earth. There are many types of mould but only a few are capable of causing both serious and mild health issues. Most moulds thrive in damp conditions. They spread by releasing millions of microscopic spores that may float through the air, travel along moisture, or even be carried by insects.

Actually, mould is part of the decomposition process of organic matter because it plays a vital role in nature by breaking down organic matter, creating substances necessary for sustaining animal and plant life. However, their effects on buildings are undesirable. What it requires for moulds to grow are oxygen, moisture, nutrients and temperatures between 40 and 100 degrees Fahrenheit.  

Causes of Mould Growth During Construction

The major reasons for mould growth during construction process is uncontrolled moisture incursion which appears in form of liquid flow, condensation, high humidity and/or capillary action that dampens building materials. Other major causes of mould growth during construction include issues relating to site, product, procedure and design.

• Site-related issues

Site related issues that can cause mould growth include poor site drainage, inadequate building protection, water buildup in basements and crawlspaces, and stored building materials that get wet.

• Product-related causes

These refer to defects on building materials delivered on site. The defects may occur before or after delivery.

• Procedural issues

These include lack of proactivity, poor quality control and non-challant attitudes with which construction engineers handle moisture incursion when it happens.

• Design-related causes

Some design flaws and defects caused by shoddy construction also allow moisture to take place.

How Mould Grow During Construction

In the early stage of construction phase, the presence of organic material is limited, especially if floors are concrete and framing is metal. The hardness of materials like wood framing and subfloors can make the materials difficult for mould to take over in the short period during which they’re exposed. However, if left exposed for a longer period of time, wood can have mould growth. Unlike wood, the soft organic matter which drywall and ceiling tiles are exposed to make them susceptible to mould. In fact, mould can begin on drywall and ceiling tiles within 48-72 hours of first getting wet.

Effects of Mould on Buildings During Construction

Mould has adverse effects on the construction project and the process. It slows down work, delays completion date, leads to incursion of extra cost and other negative effects.

• Slowed construction

The growth of mould during construction causes work to slow down as construction workers need to get rid of the sources of the moisture in order to deal with the mould before going ahead with their work.

• Delayed completion date

Slowed construction occasioned by mould incursion means that the project will be behind schedule and this automatically translates to delay in the construction project.

• Extra cost

In the case of damaged or infected materials, the cost of replacing the materials and repairing the parts of the building affected and replacing all the affected materials will impact negatively on the budget set.

How to Prevent Moulds During Construction

• Choose site carefully

One of the ways to prevent moisture incursion, which allows mould to occur, during construction is to choose the right construction site. Proper investigation should be carried out on the proposed location. Using a good location eases the construction process and prevent moisture entering in the foundations. You can also drain or grade the land to redirect rain.

• Inspect materials upon delivery

Immediately materials are delivered, they should be inspected in order to identify defects. If any material is defective, it should be returned as it may turn to a fertile ground for moisture. More so, materials wrapped with special moisture resistant can be ordered.

• Provide good storage facilities for materials

Construction materials, especially porous materials, should be protected and stored in a dry location.  They should be covered with plastic sheets to keep them dry. However, the covering should not too tight since the moist can build up in time. Don’t allow materials be delivered before they are needed and ensure you limit storage time.

• Dry already wet materials

Materials which area already wet prior to drying-in can hold moisture after a rain event, and release it back into the indoor environment after drying-in, which can then be absorbed by drywall and foster mold growth. Hence wet materials should be given enough time and opportunity to dry out before drying-in will prevent this.

• Use humidity control

Humidity control should be used for construction drying. This will make the air dry when interior walls are installed to reduce the risk of hidden mould growth in the future.

• Remove growing mould

In case you see mould growing during construction, identify and take care of the sources of moisture. If this is not done, the existing moisture will continue to breed mould. You can start cleaning up once you have dealt with the moisture but if required, contact an environmental professional for advice.

Quality Control Measures During Construction

It is possible to successfully manage active moisture incursion and mould growth during construction projects. There are environmental professionals who can assist building owners, contractors, construction managers and architects in developing proactive plans to achieve this.

Inspections should be carried out to assess potential mould growth and develop remediation plans should mould growth occurs.