Building Inspection Tips – Under the House – In-Depth

In this article, we discuss the sub-floor area of a house and the items you might need to consider if you are getting ready to sell your property. We also look at some common defects in this area and how you can check for these before an inspection takes place. But first, let’s talk a bit more about sub-floors:

What is a Sub-Floor?

A sub-floor is the foundation the rest of the property is built on. In this instance, we will be looking at two main types:

Concrete Slab

This is where the foundation of a property is a level area of reinforced concrete. If the whole property is built on a concrete slab, it will cover the full footprint of the house.

Concrete/Masonry Strip and Pier

Where the land is unlevel, the foundations need to provide a level base for the rest of the house. This is usually done by building piers or similar supports from ground level. The supporting structure for floors, walls and the roof are then constructed on these supports.

Some houses are built using more than one foundation method.

Sub-floor Void

As you can see from the photos above, where part or the entire property is built on a concrete slab, there is no sub-floor void. On the other hand, foundations constructed above ground (piers) will have a void area that may (depending on the height) allow access to look at the ground, supporting structures and foundations themselves.

Why does the inspector need access to this area?

The sub-floor (if one exists) can tell a lot about the building and its condition. Things like ventilation, drainage, condition of the construction materials, signs of pest attack (current or past) are all important aspects of any home maintenance program and a building inspector will want to collect information from this area.

How can you help the inspector?

• Ensure the inspector can get reasonable access to enter the sub-floor void if one exists. If you personally can’t be there during the inspection, make sure your representative knows where the entrance to the void is and can open the hatch for the inspector. Make sure that the entrance point is not obstructed by any items as the inspector is not able to move any furniture around as part of his inspection.
• In the sub-floor space, remove any stored or unused items to clear the space. For example, timber boards are often found to be stored in the sub-floor area. But apart from being an obstruction, they are also conducive to timber pest attacks.
• Keep receipts for any repairs/improvements carried out in this space. These can help close any information gaps that may arise from the inspection.

Common defects we see?

As your home ages, it is normal for some defects to start showing. Most of them are a relatively easy fix and, coupled with regular maintenance, will not cause too many troubles.

Below is a list of some common defects that can occur in the sub-floor area of your home.

Inadequate Ventilation:

Causes:
Inadequate sub-floor ventilation is a common problem for many home owners. And there is a number of reasons for limited ventilation, including obstructed or blocked vents, aged vents and lack of natural ventilation. Where there is not enough ventilation in the sub-floor area, condensation can start building up, increasing the risk of defects associated with damp conditions. These may include wood rot, mould and higher risk of timber pest attacks.

How to Identify:
How much ventilation is required will vary from house to house and will depend on such factors as location, run off drainage and type of soil. If your sub-floor is damp, mouldy or smelly or you have fungi growing – these are all signs of insufficient ventilation.

How to fix:
A lot of the issues causing limited ventilation can be quite easily addressed:

• Obstructions or stored items under your house can block vents and limit natural air flow. Removing these obstructions can remedy this problem.
• A buildup of underfloor soil can block the vents. Cleaning the soil away and unblocking the vents will improve ventilation.
• Older vents made of terracotta or cast iron do not allow as much ventilation as more open metal vents. Updating these vents can help.
• Where there isn’t good natural ventilation you might consider improving it by adding vents or ventilation fans.

Drainage

The purpose of a drainage system in a house is to transport water away from the property to the city’s water management systems (storm water and sewerage). Naturally, issues with your drainage system can cause water to find its way under your house, and this can cause damage.

We talk more about drainage system (including gutters, flashings and downpipes) in this article (Link to Article – On the Roof).

Leaks

Causes:
Dampness in the sub-floor could happen due to a drainage pipe, plumbing or air-conditioning leak. Water finding its way under the house if the natural water flow at the property is not directed away from the building could also be the culprit.

How to Identify:
Leaks are generally easy to see – is there any water pooling in the subfloor? Below are some examples of subfloor leaks:

How to fix:

• Check for any damaged/leaking pipes and get these repaired or replaced by a licensed plumber.
• Check to see where the water flows at your property during periods of rainfall. If yes, you’ll need to engage a building inspector or plumber to investigate the issue and suggest a repair.

Loose Timbers Under the House

Causes:
The sub-floor void is often used to store unwanted items. And one of the most common items left in the void is timber related to past building works. As mentioned earlier, this can have negative impact on ventilation and encourage dampness. In turn, timber and damp conditions will increase the risk of timber pest attack.

How to Identify:
Spotting unwanted items, especially timber is easy. See some examples:

How to fix:
The solution is also easy. Simply remove all loose timbers from under the house.

Termite/Past Termite Damage

Causes:
The sub-floor support structure is often constructed using timber – termites’ food. It is also the closest part of the building to the ground and can be susceptible to dampness, creating perfect conditions for pests. This is why the risk of timber pest attack needs to be considered. The risk is dependent on the type of construction and other conditions present at the property.

How to Identify:
There are a number of signs of termite damage to subfloors. From inside your house look out for:

• Squeaking floors
• Sagging floors
• A top floor layer that is detached from the subfloor
• Loose floor tiles

From inside the sub-floor void, look out for any signs of damaged timbers. If attack is current, you may be able to see specimens.

How to fix:

• Regularly inspect for termites (with a maximum of 12 months between inspections). Ensure the subfloor is well-ventilated and drainage is adequate to prevent moisture build-up.
• If you have active termites you will need to call a pest company in ASAP to remove and treat the affected areas. You can also set up a regular termite treatment program.
• If you do not have ant capping, consider installing it as it is designed to deter termites forcing them to build their mud tubs around the ant capping so it is easier to detect them.
• Replace any timbers that have termite damage.
• Removing all loose timbers from under the house can help deter termites.
• Sealing gaps around water and gas lines where termites may enter your home can help eliminate entry points.

Maintenance and Prevention

These are just a few things you can put in place to make your property more presentable for a Building & Pest Inspection and more attractive to potential buyers. And while you may not use your sub-floor void often (or not use it at all), there are many reasons not to neglect it. Out of sight shouldn’t mean out of mind.

A well-maintained sub-floor space will generally have less defects and their nature will most likely be minor. And addressing minor problems before they escalate will surely minimise headaches and expense.

Performing routine inspections is one thing you can do help maintaining your property and deal with any issues proactively. If you want one of our inspectors to come out and check your home, it’s easy to arrange.

To see more of our building inspection tips, please click here.

Best Regards,
The EYEON Property Inspections Team

At EYEON Property Inspections, we help you buy and sell with more confidence.