I'm thinking of investing in one for peace of mind on new slabs. Can anyone recommend a particular model or a link or two. Thanks Bri

what type of slabs bri..?

Originally Posted by Dave

what type of slabs bri..?

Concrete, as in the substrate, not for making a patio!!!! Just read what I wrote and it sounds like I'm on about paving slabs!!!!

I just ask as you need a different type for Gypsum based ones..

Originally Posted by Dave

I just ask as you need a different type for Gypsum based ones..

No just a standard, concrete jobbie. I'll cross the gypsum bridge when I get there, I've not had much to do with them really.

On cement screeds Bri, i just do a sweat test.. easier IMO..

Originally Posted by Dave

On cement screeds Bri, i just do a sweat test.. easier IMO..

Thats my normal route, just wondered if there was a good one, thats accurate. Don't want to spend a fortune, but on the other hand don't want one to get one if its not really necessary.

I think they are ok for walls if it's a cheaper one but for a 75mm+ screed then you will have to move up to a really pricey one.. could be 400 quid or so..


Google is ya friend.

[QUOTE=Dave;478038]I think they are ok for walls if it's a cheaper one but for a 75mm+ screed then you will have to move up to a really pricey one.. could be 400 quid or so..

I did have a look on ebay earlier and the prices range from a few quid to a few hundred. Its not something I know a great deal about, but if a good one is that much I'll stick to a good old bit of polythene!

One I've had demonstrated ( and considering) is the Protimeter Surveymaster. As well as having the contact measurement and the probes you can measure the moisture up to 20mm below the surface without drilling. With this you make an instant assessment on the moisture within a slab the theory being if it's dry enough 20mm down all is well. It is pricey tho certainly over £300.

Originally Posted by SandyFloor

One I've had demonstrated ( and considering) is the Protimeter Surveymaster. As well as having the contact measurement and the probes you can measure the moisture up to 20mm below the surface without drilling. With this you make an instant assessment on the moisture within a slab the theory being if it's dry enough 20mm down all is well. It is pricey tho certainly over £300.

I think when I saw ones for a few quid it seemed like a good idea, now I've changed my mind! I wouldn't use it often enough to warrant having one.

Protometer Aquant
It is ideal for checking the relative moisture condition of building elements such as solid walls and floors prior to more rigorous and time-consuming investigatives.
The Protimeter Aquant is ideal for checking behind or below surface coverings that would normally prevent a direct reading being taken.
Leak paths in shower cubicles (behind ceramic tiles), in caravans/motor homes and mobile homes can be identified with the Protimeter Aquant before visible water damage occurs.
Also, this instrument may be used for surveying GRP boat hulls for the early detection of damp spots that could lead to blistering caused by osmosis.
The Protimeter Aquant has a digital display that is synchronized with a colour-coded LED scale. The display shows the relative moisture level of the material under investigation on a scale of 0-999 and the colour coded LED scale indicates the material’s moisture condition.

Surveymaster
Building Surveying
ideal for assessing the moisture condition even under a sealed surface like vinyl / wood flooring and tiled walls. The readings are displayed digitally through the built-in LCD display and supported by a color-coded scale enables a simplified method to assess the moisture level at a glance - Dry, Borderline and Damp.
Measure Mode
Utilising the two-pins at the top of the instrument, a direct reading of the moisture level can be read. The numerical values displayed in the LCD display represent the actual percent moisture content of wood (% MC) and the wood moisture equivalent (WME) of concrete, dry wall and other materials.
Optional hammer electrode and deep wall probes can be used with the Mini to measure the moisture level at depths in walls and floors, regardless of the surface condition. These options are useful accessories when investigating the cause of moisture problems within buildings.
Search mode (non-invasive)
Measures moisture beneath the surface without drilling holes to a nominal depth of 0-20mm. Hold against the wall to allow a radio signal to penetrate the surface. This is the best method for assessing the moisture content beneath a tiled / covered surface.

Hope this helps...

Tramex do a good range. I use their moisture encounter meter myself. No idea how much it costs though.

A 20mm down reading isn't much cop on say a 75mm screed is it.. the damp will be further down and will still rise when covered.... Sweat the bugger out i say..

Originally Posted by Dave

A 20mm down reading isn't much cop on say a 75mm screed is it.. the damp will be further down and will still rise when covered.... Sweat the bugger out i say..

Moisture travels upwards ( I think we all know that) and on the surface it evaporates so the highest moisture reading will be just below the surface assuming there isn't source moisture underneath.

Very true sandy but i saw a floor layer take a reading once and it was well within the standards and then he proceeded to lay the carpet.. 2 weeks later the carpet was damp... moisture deep down had not fully dried and the carpet made the floor sweat.. Hence the damp carpet..

This is my main reason for sweat testing.... but Damp meters of a good quality will do the job.. i have not disputed that.. just a lot of money for something a tiler would rarely use IMO..

the only way to test concrete subfloors is with a hygrometer like protimeter hygromaster, protimeter mms or tramex cmexpert either by drilling floor and putting in the plugs or with a hygro box. All other damp meters are for wood but caan be used on concrete to give you best places to test. Rh% is the measurement british standards dictate otherwise you're liable for a failed floor. This should be done for every job and takes minimum of 48 hours to test.

Originally Posted by tarkett85

the only way to test concrete subfloors is with a hygrometer like protimeter hygromaster, protimeter mms or tramex cmexpert either by drilling floor and putting in the plugs or with a hygro box. All other damp meters are for wood but caan be used on concrete to give you best places to test. Rh% is the measurement british standards dictate otherwise you're liable for a failed floor. This should be done for every job and takes minimum of 48 hours to test.

That's not right......not right at all.

check with british standards it's the only test they will back up

Originally Posted by tarkett85

check with british standards it's the only test they will back up

I suggest you do check lol lol.

so what test should be applied to satisfy the bsi ?

I would be very interested to know please

THe British standards recommend exclusively the hair hygrometer. This is covered in annex a of bs82042003 and is referenced in several other standards. When we talk about British standards though we are talking about a guide to best practice. British standards don't "back up" anything. In fact there are areas of the industry which do not have a British standard associated with them at all. People place far too much reliance on British Standards especially when you consider that there are several elements to a floor which are covered in differing standards each in conflict with the others. British standards have no legislative or contractual authority in themselves. If you don't follow them they can't take you o court an due you.

Just because a test is not covered by a British standard does not make it an invalid test. You can measure the moisture in a concrete slab in several ways including a carbide bomb, an oven dried sample, an electronic resistivitity meter, hygro hoods, and several others.

A method simply has to yield accurate and repeatable results in order to be useable. Some of these non British standard methods are covered in other standard documents eg bba certification, European standards, ASTM standards, CSM standards, technical guidance documents and manufacturers standard methods etc etc etc....

Thank you Ajax123

for a tiler which piece of measuring equipment would you recommend for use on both concrete and gypsum based floors ?

Rob

hi i have a £35 one ,not sure wot make ,but all i can say is that we had a guy turn up and do a test for us useing one that cost £2500 and it give the same reading my one did ,lol

Originally Posted by TT Tiling

hi i have a £35 one ,not sure wot make ,but all i can say is that we had a guy turn up and do a test for us useing one that cost £2500 and it give the same reading my one did ,lol

On what substrate though ?

[QUOTE=Sir Ramic;563802]On what substrate though ?[/QUOTE
concrete floor

only interested in ajax123's opinion thanks, sick of all the conflicting opinions on gyp floors.

I have a meter

I personally use two methods predominantly. The first is the tramex moisture encounter meter which works on both concrete and gypsum screed. About £500 worth so not something i would expect most tilers to have. The problem with this on gyp floors is that it can be misleading so you need o have a bit of experiencewith the floors so you can interpret the results. For this reason I always back up a result with an analogue surface hair hygrometer which is freshly calibrated after each use. I trust this method 100%. If the Tramex says its wet then I dont bother with the hygrometer as it is pointless. You can use digital hygrometers which ou can buy for about £80 but these work differently an can be prone to innaccuracy when outside the range about 70 to 85% so if ou get a reading of above 85% you can say its not dry but you can't accurately say by how much. The accurate range is fine though cos it spans the readings we want I.e. 75% and below for cement addy and 85% and below for gypsum addy.

Occasionally I will break out a sample or laboratory analysis and very occasionally use the polythene bag test as an indicator