Rising damp cause found after 30 years

By: admin | Posted on: July 25, 2020

This property has been suffering from damp issues for a number of years, and it hasn’t been diagnosed correctly. I was told there were a few suggestions as of why it was thought to be damp, but we have found the cause now. Before you even think about damp proofing a building, it is about elimination before coming to a conclusion. I’ve seen many a times when a damp survey Company have carried out a damp survey, and haven’t eliminated anything in regards to potential causes of rising damp. In this case, this is a classic example of an obvious cause of rising damp, but unfortunately for some people who have paid for a damp survey there is no drain inspection carried out. Now i’m not saying that every property should have a drain survey, but there is British Standards in regards to damp surveys that actually mention this, especially if you have damp internally adjacent a drain. See below from British Standard BS 6576 4.2.1.3 d)

So the question is why doesn’t this get inspected? In my opinion if you ask any surveyor whether the firm is independent or not they will probably not offer a drain survey as this isn’t a piece of equipment they actually have. So it’s unlikely at enquiry stage they would want to lose out on a survey. To be fair though, any prior conversation the surveyor might have had with the client, they might think that from your observations the damp might be more condensation related, and this is reasonable. A decent CCTV drain inspection camera will cost around £5000.00 / £6000.00, plus you will need jetting equipment, and cleaning equipment along with sonde detection. All of this is likely to cost around £15000.00, plus a van to carry it in. You can now see exactly why a general surveyor wouldn’t offer this service.

We have heavily invested in our surveying equipment to ensure we get the diagnosis right first time. If you need a CCTV drain survey along with quantitative moisture analysis following BRE DIGEST 245, please contact us to discuss your issues.

The video below shows the cause of the rising damp. This was caused when the tarmac path was installed over 30 years ago, and damaged the drains.


Calcium carbide meter/speedy meter test

By: admin | Posted on: June 1, 2020

It is presumed by the way of the self proclaimed damp experts that the calcium carbide meter, or also referred to as the speedy meter, is in fact the most reliable form of moisture measurement when it comes to identification of rising damp. Unfortunately most don’t really understand the limitations of the damp measuring instruments, and don’t follow the guidance as per BRE DG245, where part of the sample should be put aside for the hygroscopicity determination.

I own, and have used a calcium carbide meter on many occasions, and in my opinion when measuring moisture, when there is the potential for rising damp and hygroscopic salts this instrument can be massively misleading. I personally only use this when inspecting flood damaged buildings that are more of a modern construction that would unlikely to be contaminated from hygroscopic salts, from a genuine long term rising damp. The reason for this is because you can’t determine what is actually going on regarding the amount of moisture, and giving the correct advice to fix the issues.

Example explanations

The below picture shows the total moisture content of a calcium carbide meter reading of a sample removed from the wall, and placed inside the speedy meter. As you can see it gives a total moisture content of 16 %. The total moisture content (16 %), is made up of the capillary moisture, and the hygroscopic moisture. The speedy meter doesn’t give a figure for these separate amounts, which is the misleading part.

The below picture shows an example of the total moisture content broken down into the capillary moisture, and the hygroscopic moisture.

The below picture shows the same total moisture content as in the above picture, with a capillary moisture content of 1 %, and a hygroscopic moisture content of 15 %….. completely different.

calcium carbide meter

The above images explain the total moisture content, and show that it is impossible for interpreting different moisture content results, without understanding the capillary moisture content, and hygroscopic moisture content on site.

Lets now look at another example with some more guidance of why it is so important to differentiate between capillary moisture and hygroscopic moisture. This is from one of my recent surveys where a traditional solid wall property with no physical damp proof course installed has been damp proofed because it was presumed the property had genuine rising damp and needed a new damp proof course. During this survey I removed samples of plaster/mortar for analysis, and worked out the exact amounts of moisture using the gravimetric laboratory methodology. You can see in my graph below the total moisture content has been split up, to include the capillary and hygroscopic moisture content.

What does this graph show? This is the most important part…. what it shows here, is that there is a very high amount of capillary moisture content, and a low level of hygroscopic moisture content. This is not what you would see on a genuine long term rising damp issue, as you would normally see more of a distinguished hygroscopic salt band. This property actually had issues with drains that I picked up with our CCTV drain survey. The samples were also chemically tested for nitrates and chlorides (hygroscopic salts), and none of any significance were present. All of the data points to drainage issues or possible leaks, and this couldn’t be observed from an onsite calcium carbide meter test. This property needs to be dried down with a Corroventa desiccant tented drying equipment, and the drain issues rectified.

The below graph is something I see often where a physical damp proof course has been installed from new when a property was originally built. The total moisture content is 5%, and so is the hygroscopic moisture content, and the capillary moisture content is 0 %. How could you give suitable advice to your client if you couldn’t differentiate these moisture contents?

What this actually shows is that there is no capillary moisture. Capillary moisture content, is only present if there is a source of water/free moisture such as rising dampness. The amount of capillary moisture content will depend on the permeability, porosity and severity of the water ingress. The absence of capillary moisture indicates that a material is ‘dry’, that is not subject to water ingress from any source. This means normally that the damp proof course is most likely to be bridged, by plaster, debris in the cavity, or perhaps the floor screed. By also chemically testing the mortar samples for nitrates and chlorides, we can prove if these are present. If these are present as in this case, the repair was to remove the bridging issue, along with a suitable plaster repair.

BRE DIGEST 245, BRE DG 245, CALCIUM CARBIDE TEST, SPEEDY METER TEST

Capillary moisture / Free moisture

The second component is the free moisture content which is only present if there is a source of water ingress such as rain penetration, rising dampness. The amount of free moisture will depend on the permeability, porosity and severity of the water ingress. The absence of free moisture indicates that a material is ‘dry’, that is not subject to water ingress from any source.

Ground water salts:
Not only is the distribution of moisture required, we also need to obtain details of past activity of rising dampness, and this can be obtained from the presence and distribution of ground water salts, basically chlorides and nitrates. Where a long term rising damp complex has existed, these salts will always mark the maximum height to which water has risen, and tend to form a concentration (‘salt band’) around the maximum height of rise. I often find on very old properties that have been subjected to long term rising damp over many years, sometimes two distinguished salt bands. Thus, even if water ceases to rise the salts will still remain and ‘mark’ the maximum height once reached. It is the relationship between the distribution of moisture and salts that is the basis of the investigation.

The information regarding speedy meter testing of moisture and gravimetrics has been published and documented by Building Research Establishment (BRE) for many years. The earliest copy I have is the TIL 29 version which was revised in April 1977, and the latest version is BRE DIGEST 245, also known as BRE DG 245. The latest version of this document is from 2007.

Very important extract below from DG 245 2007 edition

Experience has shown that some building materials possess an HMC of up to 5% even without the introduction of salts from external sources. Although only a rough indicator, the 5% threshold does represent a reasonable general guide to whether or not some kind of remedial treatment is needed. This emphasises the importance of the difference between the HMC and MC measured on samples. It can also be useful to establish the MC and HMC of wallpaper, plaster and render, although drying plaster above 35 °C will drive off hydration water bound within the plaster and must be avoided. The figure of 5% at the base of the wall (the wall/floor junction) can be taken as an approximate guide to the presence of rising damp. However, even at this low level of moisture there can be a risk of damage to finishes and rot to any timber that may be in contact with the wall.

If you like this kind of geeky facts on damp, you might like this one that has some screen shots from the British Standards www.completepreservation.co.uk/rising-damp/http://www.completepreservation.co.uk/rising-damp/


Long term damp issue

By: admin | Posted on: May 22, 2020

Easy damp survey today. After having previous damp repairs carried out to their property that have subsequently failed, they decided to try and find a damp specialist surveyor that actually wants to eliminate issues before coming to a conclusion of why there is a damp problem.

In this instance the previous surveys, and works were more of a quote to repair a visual damp issue. Unfortunately no drains were tested or leak detection tests were carried out, so the same conclusion was given, and that was to install a dpc (damp proof course).

I tend to find there can also be at least a couple of things that always need to be rectified, but in this instance there was one issue. Because the cupboard was full to the brim the previous damp specialists failed to inspect inside the cupboard where the rising water main was. There was a small leak on this, but it wasn’t visible in the cupboard because of the vinyl floor covering. I also did drill a full gravimetric profile just to prove if there were no hygroscopic salts present, which would be indicative of long term genuine rising damp issues.

Top tip

Expect to pay for a damp survey, and expect to have an invasive survey where plaster samples are removed from the wall, and tested following the methodology in BRE DIGEST 245. It’s always prudent to have a drain CCTV survey to check for any defective drain issues, and even possibly a leaking mains water pipe.

If you need a damp survey where you want to be sure all issues are eliminated, to offer a long term solution give us a shout 🙂


No damp proofing needed

By: admin | Posted on: May 20, 2020

I was recently asked to survey a property that had visible damp issues internally.

I was informed that a ‘damp specialist’ had already visited the property, and had diagnosed rising damp issues, and subsequently recommended a chemical damp proof course has to be installed to fix the rising damp issues. This was carried out around 3 months prior to my survey.

The property is a 1970’s 2 bedroom ground floor flat, this being cavity construction along with a physical damp proof course installed from new.

Any survey starts with the basics like the reported history, the tenant/homeowner that lives in the property can give you so much info that can help with the diagostics especially if it’s only a snap shot survey.

There is often lots of controversy regarding damp meters, these are an excellent tool when used appropriately-there often not though. The pattern of readings I found on the wall when profiling from floor to ceiling didn’t replicate any form of a rising damp profile.

Observations

I noted visible dampness when a bed was pulled out from the wall, mould was noted on the bed, small amounts of condensation on the windows. A very small amount of condensation at the base of the bedroom external walls, mostly behind furniture.

When carrying out surveys I find my Flir T600 gives a great understanding of the building fabric, especially during snap shot surveys. I use this meter linked to a Flir MR77, to produce an isotherm. An isotherm is basically a blue colour on the screen that shows everything at dew point (condensation occurring). What I can also do is change the temperature up or down to find at risk areas, and check these areas with moisture meters etc for patterns of dampness.

flir0815
flir0816-copy

Below shows a visual of the dampness to the wall, possibly a tide mark from rising damp or something else.

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The below shows mould growth on the wall, mould will not occur on the wall if there has been a long term rising dampness problem with subsequent salts.

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The below shows the paper was easily peeled back with no damage. Sample pots along with a slow speed drill are being used to collect plaster samples to see if there is any free moisture in the wall (behind the surface-about 20mm in). I follow the methodology in BRE Digest 245 for quantitative results.

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This is as simple as it gets, and for some reason lots of surveyors never carry out this very basic procedure. We know there is dampness to the surface of the wall, possibly condensation, now after I have drilled out a small sample, I then check the wall with an insulated deep wall probe-this shows if the dampness is at the surface or in the wall is dry. We now know that in the wall is dry, and the surface is damp, we can now carry out profiling up the wall every  just to see if there is a pattern to the dampness issue or another possible issue.

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Green indicates a dry reading.

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Dry.

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You can see the holes where I have taken the samples

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Holes filled no visible damage from my destructive survey, the paper was put back into place – happy days.

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Externally I noted the walls have had retro-fit cavity wall insulation, the visible chemical damp proof course drilled, and some blocked drains.

Click the link to the below video to see what I could see during my inspection.

One thing that concerned me the most was that the damp proofing technician actually drilled the damp proof course through the physical damp proof course!!! Not only that the pointing looked like he applied neat cement with the palm of his hand to cover the injection hole…….not even the slightest attempt to blend in with the original mortar, like he wanted everybody to see his first class bodge up!

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Blocked cavity.

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Chemical damp proof course drilled through physical damp proof course.

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The chemical damp proof course from another angle.

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No comment!

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This issue was a condensation problem, nothing to do with rising damp, and the damp proof course that was drilled into the outer skin only was a complete waste of time.

I know I take longer to do my surveys than some of the other local damp specialists, but I think I offer value for money 🙂


Rising damp survey Wiltshire

By: admin | Posted on: January 12, 2020

This shows the very basic damp issues can get confused by some damp survey specialists. In this instance you will see the value of having a paid survey following the methodology in BRE DIGEST 245, which is the only quantitative way to measure moisture, and confirm rising damp with a moisture profile.

My client had a number of free damp surveys and the damp issues on the external wall had been diagnosed as rising damp two times, and also hygroscopic salt damp. This was all diagnosed with a damp meter only, and this isn’t what any of the BRITISH STANDARDS recommend.

When I used the damp meter with the two pins (wme mode) just to map out the moisture in the wall, I noted there were no high readings at the base of the wall, or the skirting board, which would provide a more reliable reading regarding moisture. What I did note was higher readings at high level when the damp meter was used in search mode.

Externally the building is solid red brick and exposed, now this is important because we know there can be a possible issue with penetrating damp because of wind driven rain. On further inspection I noted issues around the lintel that would allow penetrating damp an obvious route into the building.

Now I can understand why the damp surveyor thought it could be hygroscopic salts because often these can be found at higher level. I can’t understand how the other damp surveyors thought it was rising damp, and that a new damp proof course would fix the issues. I can’t understand that the damp surveyors never actually noted the location of the property in regarding the exposed position, and also the external defects.

The below graph shows the moisture profile following BRE DIGEST 245 carried out by Complete Preservation. This visually shows to even a layperson there is no capillary moisture at the base of the wall and that higher levels of capillary moisture are at ceiling height, that are adjacent the external defect. There are no hygroscopic salts present, and no high levels of hygroscopic moisture, which indicates there isn’t a rising damp issue, and never has been a long term rising damp issue.

BRE DIGEST 245 MOISTURE PROFILE

Now whats the solution of repairing the damp issue?

Simply fixing the external defect by carrying out some lime pointing where voids are visible. And then drying the wall down with tented desiccant drying equipment to ensure there is no risk to the timber lintel. Whilst there is an initial survey fee, you can see the value in this, and also the cost of repairs are a lot cheaper than a new damp proof course and plastering. Oh, and there is no disruption and mess to deal with 🙂

We carried out the lime pointing repairs, and the installed the desiccant drying equipment, and signed it off as dry when finished. The client was also a guest on our SuperVision real time moisture data loggers so they could actually log in to see how it was drying down for a transparent service.

If you have a damp issue please don’t hesitate to get in contact with us 01225 769215

enquiries@completepreservation.co.uk


Leak detection

By: admin | Posted on: January 7, 2020

Have you got a damp problem that you can’t figure out? I find many people don’t even consider a leaking pipe buried within a solid floor. Most people are under the assumption that the alleged damp is just simply rising damp. I have also found that home owners have had a number of free surveys and are convinced they actually need a new chemical damp proof course. It’s not until naive people have spent several thousands of pounds on damp proofing that they they contact us to help them out, as they still have a problem.

Locating Water Leaks using advanced electroacoustic ground mics

When a pressurised water pipe leaks the water flows out which causes the pipe and surrounding material (mud, concrete tarmac) to vibrate. This sound, or vibration, is transmitted along the pipe (structure borne water leak noise) and through the surrounding material (ground borne water leak noise). 

With the Aquaphon A200 ground mic set listening for these water leak noises is now easier than ever before.

If you have a possible leak and need some help give us a shout…..


Rising damp & the facts you need to know

By: admin | Posted on: August 13, 2019

This is some very basic stuff showing diagrams that visually explain damp issues that just drilling a new damp proof will not solve. It is well documented in BRE Digest 245, British Standard BS 6576, British Standard BS 5250, THAT YOU HAVE TO FIND THE CAUSE OF THE RISING DAMP, ALONG WITH CORRECT DIAGNOSIS BEFORE YOU CAN MOVE FORWARD WITH A REPAIR.

I have massive issues with Estate Agents that offer their damp expert to carry out a free pre purchase damp and timber survey, and basically give a quote to do the cheapest job. The quote is referred to as a ‘report’ and is presumed to be worth something along with the Mickey mouse guarantee. These are often a couple of pages, with no mention of any possible defects or the actual cause of the damp. These are worthless, and the works always mask the visible defects, and subsequent damp issues normally occur.

If you have a property that is cavity construction it is essential that you have to eliminate some of the possible causes of rising damp. It is unlikely that the physical damp proof course has failed, or broken down. If you have a solid wall property, these below pictures can also be relevant in some cases especially if there is a physical damp proof course, or a chemical damp proof course has been installed.

The below picture shows a basic issue, this being debris in the cavity that has bridged the damp proof course.

BRIDGED DAMP PROOF COURSE.BRE DIGEST 245 PDF. BRE DG 245 PDF

The below shows bridging of the damp proof course by the path.

BRIDGED DAMP PROOF COURSE

The below shows bridging of the damp proof course by the plaster.

The below shows bridging of the damp proof course by the external render.

The below shows bridging over the damp proof course by mortar pointing.

BRE DIGEST 245 PDF. BRE DG 245 PDF

The below shows bridging of the damp proof course by the screed.

Some facts…. lots of damp proofing experts claim to work to BS 6576:2005 (This is the British Standard). BS 6576:2005 Code of practice for diagnosis of rising damp in walls of buildings and installation of chemical damp-proof courses. MOST OF THEM DONT, please read the below and read some facts published in the British Standard.

BRE DIGEST 245 PDF. BRE DG 245 PDF
BRE DIGEST 245 PDF. BRE DG 245 PDF

I have highlighted NOTE 2 BELOW.… it clearly states that a damp meter gives a qualitative reading. Gravimetric tests give more detail, this will tell you exactly what is going on. Chemical tests, this is a speedy meter or a carbide meter will only show a total moisture content. Gravimetrics differentiate between hygroscopic and free moisture contents….. this is the only way we carry out our surveys.

BRE DIGEST 245 PDF. BRE DG 245 PDF

Please see the facts in BS 5250 regarding rising damp.

BRE DIGEST 245 PDF. BRE DG 245 PDF

BS 5250 also nearly states that the gravimetric method gives the most reliable results.

BRE Digest 245 states the below.

Again BRE Digest 245 recommends that  plaster/mortar samples are taken to determine what is exactly going on.

What do you do if you have a damp issue? A damp survey should be more an investigation, and you should expect to pay for it. If your damp surveyor doesn’t eliminate some very basic issues you will get a quote for a new damp proof course.

Damp meters are brilliant but they beep even when the wall is dry, if some hygroscopic salts are present, and they can’t tell you if the wall is damp by free moisture or hygroscopic salts.

All of the British Standards recommend that gravimetrics should be used to determine what is actually going on.

If you need advice regarding a damp survey, please give us a shout.

Top tip

You need to ask your damp surveyor for an invasive damp survey where as a minimum a carbide meter is used, or ideally gravimetric sampling. Most damp surveyors will only offer non invasive damp surveys, which is then an opinion not based on any data in regards to the moisture content of the wall. Drains, leaking pipes, bridging of the damp proof course are common defects that need eliminating as per the above screenshots in the British Standards. These will need to be inspected. Have a look at some interesting videos in the video gallery section of the website.