The primary time you encounter salt banding on a moist wall, it’s simple to mistake it for mould – and in equity, mould typically follows quickly after if the difficulty isn’t addressed. However salt banding is definitely the results of salts being drawn up by way of the wall and deposited in a neat, horizontal line because the moisture evaporates.
It is a frequent side-effect of rising damp and one which tends to linger lengthy after the unique moisture challenge has supposedly been mounted. What makes salt banding significantly irritating is that it behaves in a different way from abnormal damp patches or mould. The floor would possibly look sound however nonetheless really feel damp to the contact, and any try to redecorate often ends in effervescent paint or plaster that received’t fairly settle.
Beneath, we break down what salt banding truly is, why it kinds, easy methods to inform it other than different sorts of damp injury, and the proper manner to make use of a salt neutraliser so the issue doesn’t return.
What’s salt banding on a moist wall?
Salt banding is the horizontal line that seems on a wall affected by rising damp, created as moisture attracts salts up by way of the masonry. Jess Thomas, managing director of Drainage Central, explains that it’s “the seen line that signifies how excessive rising damp has reached,” shaped by salts accumulating within the wall material. These salts stay lively and proceed to soak up moisture, retaining the floor damp even after the unique downside is mounted.
Barrie Francis, damp and timber specialist at Timberwise provides that this band is brought on by hygroscopic salts – primarily chlorides and nitrates – that are left behind because the wall dries out. These salts pull moisture from the air, so the wall might all the time seem damp on the similar peak. In some instances, they will take up sufficient moisture to dissolve right into a liquid, often called deliquescence.
That is distinct from efflorescent salts, which Barrie describes because the small, white crystals generally seen on drying masonry. These will not be often hygroscopic and might typically be brushed away, whereas salt banding requires focused therapy.
Jess Thomas is the managing director of Drainage Central, and an professional within the drainage and plumbing trade. Jess frequently offers worthwhile insights on a variety of trade subjects, and is devoted to serving to householders discover efficient options to their drainage issues.
Barrie Francis is a moist and timber specialist at Timberwise, advising householders on rising damp, salt contamination and long-term moisture management, with a long time of expertise in property preservation.
What causes salt banding on a moist wall?
In line with Jess Thomas, salt banding usually occurs when a damp proof course (DPCs) is broken or lacking, permitting floor moisture to journey freely by way of the masonry. Because the wall dries, the salts naturally focus on the level the place the moisture stops, which is why the band seems in a clear, horizontal line.
Barrie Francis explains that that is the “peak of the capillary rise,” and it’s right here that salts settle through the drying course of. Their presence turns into apparent after they start absorbing moisture from the air, making a persistent damp-looking strip on the floor.
In essence, the trigger is twofold: undesirable moisture rising by way of the wall, and the salts left behind as that moisture evaporates.
The best way to inform salt banding other than mould or damp staining
Salt banding has a couple of clear markers that set it other than different sorts of damp injury. Jess Thomas notes that it seems as “a visual band or line of discolouration,” often near floor degree or round areas the place moisture has seeped in. The floor should still really feel damp, however the paint typically stays intact – not like many sorts of mould, which are likely to disrupt the end and unfold in uneven clusters.
Mould exhibits up as irregular spots quite than a straight, horizontal line, and is often linked to poor air flow and excessive humidity. Damp staining, in the meantime, is any water-related mark that disappears as soon as the underlying moisture challenge has been sorted.
If the road seems constant, low on the wall, and generally barely powdery or fluffy, it’s much more prone to be salt banding than mould or primary staining, and it received’t clear with out focused therapy.
Do you have to deal with salt banding earlier than adorning or replastering?
Treating salts earlier than you try any adorning or replastering is important, as they will forestall new finishes from bonding correctly. Jess Thomas explains that if salts stay lively within the wall, “recent paint will blister, crack, peel or flake because the salt pushes it from the wall.” As a result of these salts proceed to soak up moisture from the air, the floor by no means really dries, leaving paint and plaster struggling to stabilise.
Barrie Francis cautions that the present plaster typically must be eliminated altogether, and he recommends stripping it again “300mm past the final seen indicators of dampness,” as hygroscopic salts can sit deeper throughout the constructing material and reappear even after floor therapies. Skipping this step often leads to the identical injury returning, which is why correct salt therapy is simply as necessary as addressing the explanation for damp.
The best way to use salt neutraliser on salt banding
Salt neutraliser is a specialist chemical therapy designed to react with the salts in your wall and cease them drawing in moisture. As Jess Thomas explains, it “penetrates into the wall and reacts with the salts to neutralise them,” and may also assist kind a barrier towards future salt banding on the identical floor.
Used accurately, it creates a extra steady base for plaster or paint. Right here’s easy methods to apply it correctly:
1. Put together the wall
- Brush away any unfastened, fluffy or powdery salt deposits.
- Take away any flaking paint or clearly unfastened plaster.
- Soak the affected space with clear water so the neutraliser can penetrate extra evenly.
2. Shield your self and the area
- Neutraliser may cause burns if mishandled, so put on gloves, eye safety and appropriate clothes.
- Be certain the room is properly ventilated and canopy flooring and close by finishes with mud sheets or plastic.
3. Take a look at a discreet space first
- Take a look at the salt neutraliser by making use of it to a small, inconspicuous patch.
- Permit it to react totally and test for any surprising discolouration or floor change earlier than committing to the entire wall.
4. Apply the salt neutraliser
- Comply with the product directions for dilution and protection, then use a brush to work it evenly into the floor.
- Don’t be alarmed when you see some frothing. That is regular and easily signifies the neutraliser reacting with the salts.
5. Permit time for it to work
- Depart the neutraliser on the wall for the complete interval really useful by the producer.
- Keep away from reducing this time brief, as incomplete neutralisation can enable salts to stay lively and probably reappear down the road.
6. Wash down the floor and let the wall dry totally
- As soon as the response time has handed, wash the handled space with clear water to take away any residue.
- Don’t paint, skim or replaster till the wall has utterly dried.
- Use light air flow and background heating quite than making an attempt to force-dry the floor.
When will not salt neutralisers work?
Salt neutraliser isn’t a cure-all, significantly the place rising damp has been at play for a very long time. Barrie Francis stresses that in these instances, the plaster itself is usually contaminated with hygroscopic salts and the plaster needs to be eliminated altogether.
In extreme or long-standing instances of salt banding, particularly on partitions with a failed or lacking damp proof course, chances are you’ll be :
- Set up or restore of a moist proof course (typically through chemical injection).
- Full removing of salt-contaminated plaster to the really useful peak.
- Replastering with an appropriate damp-resistant specification, probably alongside the usage of a salt neutraliser.
In different phrases, salt neutraliser works greatest as a part of a wider damp remediation technique, not as a shortcut instead of fixing the underlying moisture supply and changing closely contaminated plaster.
Important merchandise for combatting damp and salt banding
Dryzone Renderguard Gold 5L
A specialist additive deigned for use when replastering after rising damp therapy. It neutralises residual salts and improves the brand new plaster’s resistance to moisture.
Rempro 1 Litre Salt Neutraliser
This floor therapy designed to neutralise salts on brick, stone or plaster earlier than tanking or adorning. It’s appropriate for small areas, with protection of round 5–10m² per litre.
Dryrod Damp Proofing Rods Dpc Package
A dependable solution to cease rising damp at its supply, this package helps forestall future salt banding by making a long-lasting chemical damp-proof barrier.
FAQs
Is salt banding all the time an indication of rising damp?
Not all the time, however it’s some of the frequent causes. Salt banding often signifies that moisture has travelled up by way of the wall, bringing salts with it. In the event you’re uncertain whether or not rising damp continues to be lively, a specialist can perform moisture and salt testing to substantiate and supply recommendation on easy methods to deal with damp in a particular space.
How lengthy does salt neutraliser take to work?
This depends upon the particular product, however most require a set response interval, which is often a couple of hours. It’s necessary to go away it undisturbed for the complete time really useful on the packaging so the neutralising course of can full correctly.
Can I paint straight over an space handled with salt neutraliser?
No. The wall should be washed down after therapy and allowed to dry utterly earlier than you apply paint, plaster or skim coat. Adorning too quickly can entice moisture and trigger the identical issues to reappear.
Will salt banding come again after therapy?
If the underlying moisture challenge has been mounted and the salts have been neutralised or eliminated, the band shouldn’t return. Nonetheless, if the damp proof course continues to be compromised, or if salt-contaminated plaster hasn’t been eliminated the place essential, you might even see persistent patches.
Is salt banding dangerous?
The salts themselves aren’t dangerous, however the damp situations they create can result in structural points, injury to your paintwork, and ultimately mould progress if the wall by no means dries correctly. Treating the salts is all the time really useful if you wish to forestall additional injury to your house.
For lighter floor points or common condensation on partitions, easy instruments like the very best dehumidifiers could make an actual distinction. When unsure, do not be afraid to contact a moist specialist, as this may increasingly forestall extra severe, structural injury to your house afterward.
