Property

We’ve discovered our bathroom has no foundations. What should we do?

Property Clinic: For safety’s sake and peace of mind an inspection should be carried out

If it transpires that there are no foundations, remediation work becomes more costly. Photograph: iStock

Tue Nov 24 2020 - 06:00

We’ve discovered that we have no foundations under our bathroom extension (discovered when neighbours built their own adjacent extension). We bought our home, a former council house, a year ago. The bathroom needs renovating and we just had it reroofed. We don’t have the money to renovate and put in new foundations. The extension is apparently 30 years old.

While there are no signs of any structural issue at present, we are disappointed that the absence of a foundation wasn’t identified in our survey. What are the best next steps? Many thanks for any advice you can give.

This is a startling discovery. The information provided, I assume by your neighbour’s builder, must have caused you great distress as it raises serious safety issues. Although your extension has shown no signs of structural weakness over a period of 30 years, I believe further investigation is warranted.

Let’s deal first with why this omission was not reported to you as part of your pre-purchase survey a year ago.

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There are three types of building survey: type one, two and three (T1,T2 and T3), with the most popular being T2. This should be a thorough visual inspection without opening up or investigating the concealed fabric of the building. If an issue is suspected during a T2 inspection, a further inspection to level T3 will be recommended.

For example, if significant settlement or cracking is encountered then the surveyor may recommend that foundations be inspected rather than monitoring the building over an extended period. This investigation would come at a significant cost to any purchaser and will often be resisted by a vendor because of the disruption. It is therefore unusual that a T3 inspection would be undertaken in normal circumstances.

In your case you mention that there are no obvious signs of structural issues. The foundations to a building are not visible as they are below ground. Therefore, your surveyor would have no reason to suggest that there was an issue with foundations that would warrant further investigation.

Turning to the specific issue at hand, foundations are designed to transfer the weight of buildings into load-bearing ground. The foundation will typically be three times wider than the wall it supports to spread weight over a greater area. However, this is not always the case

The absence of a visible formed foundation in your case indicates that the weight is being transferred into a narrow section of the ground.

However, there are different types of foundations and the builder may not be familiar with the type used here. For example, there is a deeper and narrower-based foundation which can be the same thickness as the wall and that type may have been employed here. In this scenario it’s likely no further action would be required.

A chartered building surveyor would be able to advise you on this. If it transpires that there are in fact no foundations, the situation becomes more complex and remediation work becomes more costly. First of all you will need to carry out some excavation work and sink some trial holes to get an accurate picture of the situation.

The addition of the new roof also needs to be considered as this may lead to additional weight being placed on the walls.

It is very unusual that a recent building would have been built without concrete foundations. Particularly an extension to a house owned at the time by a local authority. For that reason and the fact there have been no structural issues over the last 30 years, I would be hopeful that foundations are in fact in place, no further intervention will be required and that you will be free to proceed with your intended upgrade.

However, it is important from a safety point of view – and peace of mind – that the required inspections are carried out promptly. – Noel Larkin

Noel Larkin is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland, scsi.ie

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