wall cross-section
the most common
«The sweating house»
Condensation
Black mould spots in the upper corners and behind furniture. Droplets on the windows in the morning. Worse in winter and at night.
Airing: €20–300Learn more →
DAMP SEASON HAS STARTED · OCT–FEB
The mould is back.
Again.
You cleaned it with bleach. Painted over it. Bought moisture absorbers. If you don't know which kind of damp you have, you're treating the symptom — and the stain always comes back. Find the cause in 3 minutes, before someone sells you thousands of euros of building work.
Where does it show up?
FREE · NO EMAIL · 12 QUESTIONS · INSTANT RESULT
Foto: NordhornerII · Wikimedia Commons1 in 3 homes in Portugal has damp. Yours probably does too.
32.1% of the population, rising for three years in a row (INE, 2025). In January, Lisbon spends days at 90–100% humidity.
Sound familiar?
Tap the ones that apply to your home. (be honest…)
None? Great. But in winter the humidity indoors goes up — check whether your home is at risk.
Find the cause — 3 min
Foto: Tony Webster · Wikimedia Commons
Foto: Mia Primavera · Wikimedia Commons
Foto: Doggo19292 · Wikimedia Commons
Foto: Sintegrity · Wikimedia CommonsWhich one is your home?
Treating the wrong cause is the most expensive mistake: a €4,500 injection won't fix condensation, and a dehumidifier won't stop a leak.
wall cross-section
the most expensive
«The wick house»
Rising damp
Damp band up to ~1 m from the floor. White powder and salts (efflorescence). Crumbling plaster, blistered paint.
Silane injections: €35–60/m²Learn more →
wall cross-section
the most urgent
«The weeping house»
Water ingress
Yellow-brown patch with a sharp edge. Worse 1–3 days after rain. On the ceiling, near windows or under the terrace.
Terrace waterproofing: €28–45/m²Learn more →
How it works
- 01
Answer 12 questions
With pictures instead of jargon. If you have a hygrometer, measurements make the result more precise.
- 02
See the likely cause — and why
Probabilities for each type, the three signs that weighed most and how confident we are. If we're not sure, we say so.
- 03
Decide the next step
Fix it yourself, ask 1–2 verified companies for quotes or, if you rent, send your landlord a letter with the PDF report.
EXAMPLE RESULT · BEDROOM, LISBON
Likely condensation
High confidence · medium severity
Condensation86%
Water ingress11%
Rising damp3%
Why we think so: wall at 13 °C, below the dew point (13.5 °C); black mould in the upper corners; laundry dried indoors.
WHY WE'RE DIFFERENT
A company's «free diagnosis» always ends the same way: with its own quote.
We also earn money from companies. The difference is that the rules are public:
The algorithm decides
The diagnosis isn't made by a partner. There are no paid spots in the result.
If you can fix it yourself, we say so
Even when we earn nothing from it.
At most 2 companies
Your details are only shared with your explicit consent — and never with 10 companies.
Bad ratings, out
Companies badly rated by our users are excluded.
SECOND OPINION
Already have a quote? Check it for free
Tell us the type of damp, the method and the price. We tell you whether the method treats the cause and whether the price per m² is within what the market charges.
Check a quoteFOR TENANTS
Renting a damp home?
Find the cause, document it with numbers and send your landlord a ready-made letter, created in 2 minutes in your browser.
Tenant's guideTOOL
Dew point calculator
With a €20 thermometer you can tell whether your wall will grow mould. At 18 °C and 75% humidity, any surface below 13.5 °C gets wet.
Open the calculatorFOR COMPANIES
Qualified requests, with diagnosis and photos
Type of damp, area, location and timeline — before the first phone call. Each request goes to at most 2 companies. The first 5 are free.
See the termsGuides with nothing to sell
prices with sources, no paid brands
Prices7 min
How much does rising damp treatment cost? (2026 prices)
Injections, electro-osmosis and salt-retardant plasters: prices per m², a worked example, red flags and what to ask before you sign.
Full guide →Rooms7 min
Mould in the bedroom: why it appears and how to get rid of it
The bedroom is where mould appears most — and there is a physical reason for it. The plan to get rid of it, in most cases without building work.
Full guide →Tenants and condominiums7 min
Damp in a rented home: who pays, the landlord or the tenant?
As a rule, maintenance work is the landlord's job. But the cause matters: how to document, notify, what deadlines to ask for and what not to do.
Full guide →Diagnosis8 min
Damp walls: how to find the cause in 10 minutes and what it costs to fix
Condensation, rising damp, water ingress or a plumbing leak: four signs that tell them apart, a comparison table and observed prices for each fix.
Full guide →7 am, January
WHY HUMIDADE.PT EXISTS
Three companies, three «free diagnoses», three different answers.
Anyone who has had mould at home knows the pattern: each company concludes you need exactly the product it sells. Injections for one, ventilation for another, special paint for the rest.
We built humidade.pt so you know the answer before the first visit — with numbers, sources and the model's rules in plain sight. If the result looks wrong to you, write to us: we read everything and use every case to calibrate the model.
— the humidade.pt teamWrite to us →
Frequently asked questions
Yes. We don't ask for contact details to show the result — only if you want quotes from companies or the PDF by email.
A public scoring model: each answer adds or removes points from three hypotheses. The weights are on the methodology page.
It depends on the cause. We create a letter to your landlord with the report; each party's obligations should be confirmed with a lawyer.
No. It is indicative. When confidence is low, we say so and recommend a visit.