Ivy Causing Damp: What It Does to Walls and What to Do

Ivy rarely creates damp in a sound wall, but it can make an existing problem worse and hide it from view. A thick covering can slow the drying of a wall that is already wet. It can also conceal cracked pointing, blocked gutters and bridged damp-proof courses until the damage is well advanced. If you can see damp inside your home and ivy outside, the ivy is a clue to investigate, not a diagnosis.

Below we explain what the research from Historic England and the RHS actually says, how to tell ivy-related problems from leaks and other defects, how to remove ivy without harming the masonry, and when a survey is the sensible next step.

TL;DR

• Ivy’s attachment roots do not normally bore into sound masonry. Damage mostly happens where the wall already has cracks, holes or loose mortar.
• Ivy can reduce drying on a wall that is already damp, and it hides defects such as failed pointing, damp-proof course problems and blocked air vents.
• Research on ivy and humidity is mixed in its detail, so the wall’s condition matters more than the plant. Diagnose the cause before blaming the ivy.
• Remove ivy slowly, outer stems first, and expect to repair mortar, plaster or paint afterwards.
• If damp marks, mould or musty smells appear on walls behind ivy, book a survey before any treatment is chosen.

Table of Contents

• Does ivy cause damp?
• What the research says about ivy and humidity
• How ivy affects walls, mortar and timber
• Signs that ivy is hiding a damp problem
• Is it the ivy, a leak or something else?
• How to remove ivy without damaging the wall
• Repairs to expect after the ivy is gone
• Our view: survey first, then decide
• When to book a damp or timber survey
• Get the cause confirmed
• FAQ
• Sources

Does ivy cause damp?

Usually it does not cause damp on its own. Historic England says the effect of ivy on wall moisture is complicated, with no simple answer. A thick covering may shield a wall from rain, but it may also stop moisture from the ground or from building defects evaporating effectively.

The RHS takes a similar view. Ivy is often not the cause of structural problems, but a covering on a house that already has a damp problem can make it worse by limiting how much the walls can breathe.

So there are two separate questions:

1. Is the ivy adding water to the wall? Rarely.
2. Is the ivy stopping a wet wall from drying, or hiding why it is wet? Often, yes.

The second question is where most homeowners run into trouble. The damp has a source, and the ivy sits in front of it.

What the research says about ivy and humidity

The evidence does not all point one way, and it is worth knowing why.

Histic England reports research on deep-seated damp that found no evidence that ivy worsens damp-related deterioration. It also says further research shows climbing plants such as ivy do not increase relative humidity or damp within walls.

The RHS tested this on model buildings. Its experiment did not support the concern that green walls cause damp: relative humidity was 5.7% lower inside ivy-covered buildings on warm winter afternoons than inside bare ones. The same work found ivy reduced air temperatures in summer by at least 1°C.

Ivy can also protect a wall. The RHS notes it can shield masonry against heavy rain-driven winds, which cause erosion and add to damp.

This is why we do not tell every homeowner to strip ivy off. Those findings come from healthy, intact walls or model buildings. A real house with cracked render, a leaking downpipe or a bridged damp-proof course is a different case, and the ivy there may be doing harm by concealing it.

How ivy affects walls, mortar and timber

Ivy attaches with small aerial roots. Historic England says these are superficial in typical circumstances and do not penetrate masonry or draw moisture or nutrients from it. In some conditions the plant can produce proper roots, for example when the base is cut, the wall is very damp, or leaf litter has collected. These roots can enter small cracks and holes and disrupt the masonry.

The Historic England research report puts it plainly: ivy cannot actively bore into walls, but it can cause serious problems where it grows into existing defects such as holes, cracks and crevices. The greatest damage tends to occur when shoots meet darkness, moisture and weathered material inside an already deteriorating wall. This is not common, but it happens.

In practical terms, ivy growing on or into a wall can:

• dislodge masonry, mortar and pointing
• lift copings and slates
• block gutters and downpipes
• conceal damp and other defects

Historic England lists these effects in its guidance on ivy on walls. Blocked gutters matter more than most people expect, because overflowing water runs straight down the wall face. Our guide to blocked gutters causing damp inside the house explains how that shows up indoors.

On timber, the concern is indirect. Ivy that reaches fascias, soffits, window frames or roof edges can keep them damp and hide early decay. If you can see ivy at roof level or around timber windows, check those areas closely.

Signs that ivy is hiding a damp problem

The Property Care Association’s code of practice says ivy and other climbing plants may hide faults. Vegetation can also obscure the damp-proof course, defective pointing and air vents, and inhibit drying.

Look for these signs inside the property, on walls that face ivy:

1. Damp patches that grow after heavy rain and fade in dry spells.
2. Peeling paint, blown plaster or bubbling wallpaper.
3. White, powdery salt deposits on the plaster surface.
4. Musty smells in rooms with an ivy-covered outside wall.
5. Mould spotting on the wall or in the corners.
6. Staining at skirting level or around window reveals.

Outside, look for cracked or missing pointing behind the stems, damp-stained brick, leaves packed into gutters, and ivy growing under slates or into eaves.

Patches that move with the weather often point to water entering through the wall. Our guides on why walls get damp after rain and five follow-the-water checks for penetrating damp set out what to look at, in order.

Is it the ivy, a leak or something else?

This is the question that decides whether you spend money on the right repair. Damp in a wall behind ivy usually has one of these causes:

RICS says finding the cause of damp can be complex. It recommends a specialist survey and suggests checking gutters and rainwater pipes, roofing defects and external pointing. It also warns that damp meters can give high readings on materials other than timber because of conductive substances that are not moisture. A meter reading alone is not a diagnosis.

The Property Care Association says an investigation should take a whole-house approach. That means considering location, structure, materials, ventilation and the condition of the building, and noting the weather at the time of inspection. Our guide to rising, penetrating or condensation shows how those three are separated in practice.

It also helps to read about condensation versus damp, because indoor mould on a wall behind ivy is not always caused by the outside. High indoor humidity can do it alone. The Property Care Association’s code notes that mould can grow when average room humidity stays above 70% for several days, and that liquid water is not needed if surface humidity is high enough.

How to remove ivy without damaging the wall

If the ivy is blocking inspection, harming the building or hiding defects, it should come off. Historic England says ivy may need removing if it is harming a building or preventing a thorough inspection of the wall surface. It also warns that removal can further damage friable masonry, so slow and careful is the rule.

The RHS advises the following approach, and we would add a survey at the end:

1. Test a small area first. Removal can pull away paint and loose mortar, so see how the wall responds.
2. Cut and peel the outermost stems. Work steadily inwards rather than removing large sections at once.
3. Leave the main stems attached to their roots until the end. The RHS gives this sequence for removal.
4. Deal with strong root hairs gently. A wire brush, metal scraper or pressure washer can remove them, taking care not to dislodge loose material.
5. Do not simply cut at ground level and walk away. Historic England notes that cutting at the base can lead to rooting-in higher up the wall.
6. Survey the exposed wall. Once the surface is clear, check pointing, render, gutters, air bricks and the damp-proof course.

If the wall is soft, crumbling or has lost much of its pointing, take advice before pulling anything off. Our masonry repairs work covers walls where the fabric has failed.

Repairs to expect after the ivy is gone

The RHS says repairs after removal may include filling cracks and joints, re-rendering or repainting. In our experience, the likely list is:

• repointing where mortar has crumbled
• patching or renewing render
• clearing and repairing gutters and downpipes
• lowering soil or planting that bridges the damp-proof course
• opening up blocked air vents
• renewing internal plaster that has absorbed moisture and salts

Inside, plaster that has held damp for a long time can carry salts that keep drawing moisture back in. That is a matter for damp re-plastering, not repainting. If the wall shows white deposits, read about salt-contaminated plaster.

Our view: survey first, then decide

We see the same pattern on many Dorset, Hampshire and Wiltshire properties. The owner notices damp on a wall, sees ivy outside, and assumes the ivy is the cause. Sometimes it is a factor. More often it is covering something else: a failed joint, a leaking gutter, soil piled above the damp-proof course.

That is why we start with diagnosis rather than treatment. We look at the visible symptoms, record what we find with photographs, and write up clear findings and a defined scope of work. You are only offered treatment after the inspection, and our workmanship carries a written guarantee.

We also stay within our remit. If a wall needs structural input or a specialist referral, we say so in the report rather than stretching to cover it.

Tell us what you can see: where the ivy is, where the damp shows inside, and whether it changes after rain. That information shortens the diagnosis.

Quay

When to book a damp or timber survey

Book an inspection if any of these apply:

• damp, mould or salts show inside on a wall that carries ivy outside
• the ivy reaches the roof edge, window frames, fascias or soffits
• you have removed ivy and found cracked, soft or missing mortar
• you are buying, selling or letting a property with heavy vegetation on the walls
• timber near the ivy feels soft, looks cracked or has small exit holes

A survey should name the cause, show the evidence, and set out the work in writing. Our damp and timber survey covers walls and timber together. For wood showing decay, the timber survey looks specifically at rot and woodworm. Landlords can use our landlord damp and mould inspection. For a wider view of what a good inspection covers, see our damp inspection checklist.

Get the cause confirmed

Quay Point Plastering carries out survey-led damp, mould and timber work across Dorset, Hampshire and Wiltshire, with more than 35 years in the industry. We diagnose first, document the findings and agree a scope before any treatment starts. Depending on what the survey finds, that can mean penetrating damp repairs, DPC injection or condensation work, timber treatment or replastering.

Book an inspection through our website or call 01202 287134. Tell us where the ivy is and what you can see inside.

FAQ

Can ivy cause damp inside a house?

Ivy does not usually create damp in a sound wall. It can make an existing problem worse by slowing evaporation and by hiding defects such as failed pointing or a blocked gutter. If you have damp indoors behind ivy, the cause needs diagnosing rather than assuming.

Will ivy damage brickwork and mortar?

Ivy’s attachment roots are normally superficial, according to Historic England. Damage mostly occurs where the wall already has cracks, holes or loose mortar, which ivy can grow into. Removing it can also pull away weak mortar, so take it down slowly.

Should I cut ivy at the base to kill it?

Cutting at ground level is not a complete answer. Historic England notes it may lead to rooting-in higher up the wall. The RHS advises peeling the outer stems first and leaving the main stems attached until last.

How do I know if damp is from ivy or a leak?

Check whether the damp changes with the weather, whether gutters and downpipes are clear, and whether the pointing behind the ivy is sound. Constant damp unrelated to rain can suggest a plumbing leak. A survey that follows a whole-house approach separates these causes properly.

Sources

• Ivy on buildings and fences, RHS
• Ivy-clad walls keep homes cool during summer, RHS
• Benefits of Ivy, Historic England
• Ivy on Walls, Historic England
• Ivy on Walls research report, Historic England
• Damp and mould, RICS
• Code of Practice: Investigation and Control of Dampness, Property Care Association
• Condensation vs damp: what UK homeowners need to know

Recommended

• Why Walls Get Damp After Rain
• Ground Levels Causing Damp: How to Spot and Fix It
• Up to a Year to Dry: Survey Cavity Wall Damp First
• Damp in solid walls: causes, diagnosis and fixes