Symptoms mapped to likely causes, with the check that tells them apart.
Costing and commercial control. 5 questions answered below, each with the arithmetic behind it and the limits of what the tool decides. Open the Defect Diagnosis tool.
A defect is a symptom, and the symptom is rarely where the cause is. Cracking in a wall may be a foundation, a lintel, a thermal movement or a tree; damp at the skirting may be a leak three floors up. This tool takes the symptom you describe and returns the plausible causes, the observations that would distinguish them, and the checks that would settle the question. It gives several causes on purpose. Single answer diagnosis from a description is how a repair is done on the wrong element, and the cost of that is paid twice. What the tool does not do is diagnose: a photograph and a sentence are not an investigation, and every cause it returns comes with the observation that would confirm or exclude it, so the next step is a site visit rather than a purchase order.
Damp at the base of a ground floor wall, on the inside, in one corner. The tool returns rising damp, a bridged damp proof course, a leak from above following a cold bridge, and external ground levels above the course, each with the observation that separates them: the height of the tide mark, whether it appears after rain, whether the external ground is above the course, whether there is a downpipe nearby. None of those can be answered from a description, and the tool says so rather than picking rising damp because it is the most familiar.
It takes a described symptom and returns the causes that could produce it, the observations that would distinguish them and the checks that would settle it. It is a structured starting point for an investigation rather than an answer. The value is in not committing to the first explanation that comes to mind, which is usually the one that was seen most recently on another job.
No, and it is deliberately built not to. A diagnosis from a description is a guess with confidence attached, and building defects are exactly the area where a wrong guess is expensive: a damp proof course injected where the problem was a leaking downpipe costs money and does not fix anything. What the tool gives you is the shortest list of plausible causes and the tests that separate them.
Because one symptom usually has several. Damp at a skirting can be rising damp, a bridged course, a leak, condensation or a cold bridge, and each has a different remedy and a different cost. Giving one cause would be a coin toss presented as an answer. Giving four with the observation that separates them turns the problem into something that can be investigated in an afternoon.
No. It diagnoses the cause, or rather it narrows the causes. Repair pricing needs the extent, the access and the method, which are known after an inspection. A repair price given before the cause is confirmed is a number that will change, and quoting one is how a small job becomes a dispute.
From the documented causes and failure modes of common construction details, and from the observations that distinguish them. It is a knowledge base rather than a model's opinion, and it is deliberately conservative: where the description does not distinguish between causes, it says what further information would, instead of choosing.