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Damp Plaster, Concrete & Wood – How Fast?

In the UK, there are 3 building materials that you will likely come across inside properties (if we call bricks an exterior material) and they are plaster, wood and concrete. These can be found in various elements of a building fabric, including walls, floors and ceilings. Consequently, damp plaster, wood and concrete is something we come across regularly when doing our work.

Damp Plaster, Wood and Concrete
Pre Damp Plaster, Wood and Concrete

As experts in water leak detection and water damage, we are very familiar with tracking down the tell-tale signs of damp plaster (and damp plasterboard), wood and concrete. This is helped greatly by sophisticated, professional moisture meters which are often used as one of the best leak detectors also.

In fact, we utilise a range of moisture meters do do what we call ‘moisture mapping’, with some meters designed for particular materials – a good example is the Tramex Concrete Moisture Encounter range which (amongst other things) as the name suggests is good for measuring damp concrete in particular.

Damp Plaster, Wood and Concrete

Something that people ask us is whether or not these three materials absorb water, how much and how quickly. So we thought to help demonstrate that, we would do a simple test!

This can be seen in the video below, with more detail and statistics below that:

The tests for damp plaster, wood and concrete started with ‘dry’ materials. We say ‘dry’ because they all have a stable / ‘natural’ level of moisture within them. They are not 100% dry. How much moisture is in these materials will depend on a number of factors, including:

  • What exact materials they are made of
  • With wood for example, what type it is
  • The environment it is kept in, including;
  • How much it is exposed to moisture, damp or condensation
  • The time of year, season and weather (including humidity)
  • Is it indoors, outdoors etc.
  • Many other factors are considered

So, as you can see, you can’t simply say “Item X has 10% moisture, so it is dry”, it may normally be 3 or 4%, in which case, comparatively, it is wet vs it’s normal levels. One of the reasons we always take control readings. On the topic of humidity, we have a really valuable guide to reduce humidity in homes.

So, here are the weights of the objects before the test:

Pre-Damp Plaster, Wood and Concrete Test
Pre-Damp Plaster, Wood and Concrete Weight

As you can see:

  • The ‘dry’ pre damp plaster weighed 44g
  • The wood (softwood) was 34g
  • The concrete was 65g

So relatively speaking, the most dense material was concrete, then plaster, with wood the lightest. But will that affect the results of how much water they take onboard? Let’s take a look.

Getting Damp Plaster, Wood and Concrete

In order to get to a situation where we have damp plaster, wood and concrete we simply submerged them in tap water (good old H20!) for a day, taking readings of weight after a day and 24 hours.

Damp Plaster, Wood and Concrete (wet)
Damp Plaster, Wood and Concrete (wet)

Interestingly, as you can see in the picture above (and indeed the video previously) the plaster and concrete started to bubble immediately. This was a good indicator that they were taking on moisture quickly, with air bubbles being replaced with water – also demonstrating they are somewhat porous materials too!

Let’s take a look at where we got to after 1 hour of being underwater:

Damp Plaster, Wood and Concrete after 1 hour
Damp Plaster, Wood and Concrete after 1 hour

The results are extremely interesting, as you can see:

  • The (now) damp plaster weighed 56 grams (+12g / +27%)
  • The damp wood was now 36 grams (+2g / +6%)
  • The damp concrete was now 77 grams (+12g / 18%)

Firstly, notice how in the UK we usually say grams not grammes (although both are acceptable nowadays) but also remember that 1 gram of water is 1 ml (millilitre) of water so we know the amount of water each has ‘taken onboard’, aka absorbed (not to be confused with adsorbed!) within it’s structure.

Secondly, it is interesting that the concrete and damp plaster took on the same amount (12g) but, as a percentage of their additional weight, the plaster took on more. In comparison, the wood only added 2g in weight.

Damp Plaster, Wood and Concrete (after 1 day)

We then re-submerged each of the 3 materials for another 24 hours / 1 day and re-weighed them. The results were fascinating to say the least!

Damp Plaster after 1 day
Damp Plaster after 1 day (Weight)

As you can see:

  • The damp plaster was still 56g (+12g / +27%)
  • The concrete, likewise was unchanged at 77g (+12g / +18%)
  • However, the damp wood was now 56g (+12g / +35%)

This is interesting for a few reasons:

  • Completely coincidentally all had added 12g
  • The damp plaster and concrete were saturated after just 1 hour
  • Surface area may have played a part in this
  • The wood continued to add moisture over time
  • It actually added the most in percentage terms given its lower start weight
  • This is likely a good comparison of a more capillary vs porous material
  • The wood started more slowly but caught up and overtook the others in %

How Much Water Was Added?

As we just said, they all added 12g of water, which is 12 millilitres. To help illustrate this, we added this amount to a small glass with food dye to help visualise it:

Damp Building Materials
Damp Building Materials – Extra Water

It is interesting to see how much that is, especially in relation to the size of the 3 objects. They may look solid but clearly they are not. Relatively speaking, all three took on moisture a lot and all within a day.

This is why we always say that when you have a water leak or water damage, act quickly to avoid things getting too damp and do not ignore it, which can lead to property damage. Something we see a lot as a damage management company, including when people have an underfloor heating leak.

The charts below help to visualise and explain this too:

Damp Materials - Analysis Chart
Damp Materials – Analysis Chart

On the subject of acting quickly when you see damp or a leak, something else we spotted which we will look at in the next section was the damp plaster in particular.

Damp Plaster – Additional Observation

When we finished our experiment, one of the materials stood out from the others, the damp plaster. Why? Well whilst the concrete (especially) and the wood had largely held their form, shape and strength the plaster was showing signs of degrading after just 24 hours of contact with water, which is not long.

We look at these materials dry after water damage from a leak in our concrete leak article.

There were fragments that had broken off and it had started to become a bit mushy. We actually think that it lost a gram or two into the water it was submerged in. To be honest, this was not particularly unexpected!

We are sure that those of you who have had a ceiling leak have seen plaster and plasterboard get mis-shaped and bow with the water / damp it is exposed to. We see this very often – plaster and plasterboard do not stand up well to moisture and often need to be replaced, especially as often you see mould problems too.

Damp Plaster Window Mould
Damp Plaster around Window – Mould

We discuss how damp plaster can lead to mould in our article about Christmas mould, which is a really useful read and explains why mould in houses is more common in winter months, including December.

As experts in damp and mould, we can help you deal with this.

Damp Plaster – Top Tip
“Wet or Damp Plaster or Plasterboard is especially susceptible to problems with mould growth. It is a material which can get damp quickly and provides organic nutrients that mould thrives in so be extra vigilant for damp on walls which are covered in plaster.”

Leak Detection Team

Damp Plaster – Related Articles

Here are a few other useful articles related to this subject which you may find interesting to review too:

If you have a water leak contact our friendly and experienced team for help.

Rainbow Restoration Leak Detection
Rainbow Restoration – Leak Detection

How do you fix damp in plaster walls?

Rainbow International - Damp Problem, York and North Yorkshire

How you remedy damp plaster on walls will depend on the cause of it is (which could include rising damp, penetrating damp, a water leak or condensation) and the extent of the damage caused. Plus, not all plaster is the same – some are solid, some are plasterboard and some are lath and plaster. Each are treated differently, depending on age too!

Do I need to replace damp plaster?

Damp Survey - Water Leak Detection. York, North Yorkshire.

This will depend on a number of factors. Firstly, how bad the damage is, which in turn will be related to the amount of water / moisure it has been exposed to and how badly affected it is (which could include mould damage too). Plus the type of plaster it is, the age and construction method. Many factors are considered but replacement of damp plaster is not uncommon, especially as it can get weakened and distorted easily.

Will damp plaster dry out?

Water Damage - Property Drying, York and Yorkshire

This will depend on where the plaster is located, how badly affected it is and (for example) if it is painted. For example, gloss or silk paint can ‘trap’ moisture which would not escape without assistance from drying (dehumidifiers etc). Plaster can dry out on its own, but it is commonly better to do this with special drying techniques and equipment. An additional thing to consider is that damp plaster can lead to mould problems if it is not dried, which causes other problems.

At Rainbow Restoration – York & Yorkshire Coast we are experts in Leak Detection, including commercial leaks, so if you need help finding a water leak or getting your property back to normal after a water damage or a flood, get in touch with our friendly local team who will be happy to help you with this. We are based in York and help find water leaks in York.

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