Structural survey or engineer's report: which one do you need?

The difference between the two

A standard pre-purchase survey is a visual inspection of the whole home, inside and out. It reports on the roof, the walls, damp, the windows, the heating and the services. It is the right survey for most second-hand homes, and it costs €300 to €600 plus VAT.

A full structural survey asks one question: is the building sound? The engineer looks hard at the parts that hold the home up:

• the foundations, as far as they can be judged from the outside and from cracks
• the load-bearing walls, lintels and beams
• the roof structure, in the attic, not just the tiles
• the floors, and whether a joist has been cut or has rotted
• any extension, and how it joins the original building
• movement: cracks measured and photographed, doors that stick, floors that slope

The structural report can also include opening up a small area, a drain test, or a sample of the blockwork for a pyrite or mica test. Each of those costs extra and needs the seller's permission.

You do not need both. A structural survey covers what the standard one does, in more depth, and costs more.

When a structural survey is worth it

Ask for the deeper survey when any of these is true:

• the home was built before about 1960, or has solid walls with no cavity
• there is an extension, an attic conversion, or a wall has been knocked through
• you can see cracks wider than a coin, especially stepped cracks in the brickwork
• the home is in an area with known pyrite or mica problems
• it has been empty for years, or it is derelict
• you plan to renovate, extend or take walls out, and you need to know what you are starting with
• a standard survey said to refer it to a structural engineer

The last one is common. A building surveyor sees a crack, cannot say what caused it, and asks for an engineer. Paying for the engineer at that point is the right call: a crack can be nothing, or it can be a foundation problem that costs tens of thousands.

For a vacant or derelict home, the structural survey comes before you bid, not after sale agreed. The grant works are costed from it.

What it costs

A full structural survey costs €1,500 to €3,000 plus VAT at 23%. The range depends on the size and age of the home, how far the engineer travels, and whether any tests are added.

Tests on top:

• a pyrite or mica test of the blockwork or the hardcore under the floor: a sample is taken and sent to a laboratory, and the fee depends on the number of samples
• a drain survey with a camera
• a damp specialist's report

Ask for each as a separate line on the quote. You may not need all of them, and the engineer should say which ones matter for this home.

Against that, set what it protects. A home with a structural problem can be very hard to sell on, and a lender may refuse to lend on it at all. The engineer's report is also what you use to go back on the price, or to show the lender that a problem has been assessed and can be fixed.

The table below gives the typical ranges from our costs config, not a quote.

Pyrite, mica and the tests

Pyrite and mica are minerals found in some building blocks and in the hardcore under floors. When they take in water they swell or crumble, and the walls or floors crack. Homes built in the 2000s in some counties are affected. A government redress scheme exists for some owners, but a buyer cannot count on it.

If the home is in an affected area, or was built in the years when the problem happened, ask the engineer about a test. A test means taking a core sample from a wall or the floor and sending it to a laboratory. The seller must agree, and the hole is made good afterwards.

A clear test does not cover every wall, but it is the only evidence there is. Without one, a lender may still lend, but a future buyer's engineer will ask the same question. If the seller refuses a test on a home in an affected area, treat that as a warning.

What happens after the report

The report gives each defect a cause, a severity and a fix, often with a rough cost. Three outcomes are common:

1. The building is sound. Normal cracks from the home settling, nothing structural. You go ahead, with a budget for the ordinary repairs.
2. A problem with a fix. A lintel to replace, a wall to tie, a floor to relay. Get a builder's quote, then go back to the seller through the agent, in writing, with the report attached. You can ask for a price drop or walk away before contracts.
3. A problem without a clear fix. Ongoing movement, a failed foundation, a positive pyrite or mica test. Most people walk away. If you go ahead, tell your lender: it may want the engineer's report before the loan offer, and it may refuse.

Send the report to your solicitor either way. Any extension or structural change without planning permission or a certificate of compliance goes into their questions on the title.