Anhydrite screed........

[Old Mod]

There are 3 tests that can be done. Oven dried sample which is usually lab work so dispute territory. Hair hygromerer which is fine provided it is done correctly...many many hygromerer are incorrectly calibrated or used inappropriately. And carbide bomb which is the quickest. my preference these days is the carbide bomb. Indie some training for mapei a while ago and stressed this point so thats probably where it has come from.

Not easy things to source tho Alan, can you point us in right direction?

 

[Ajax123]

I think mapei may actually sell them.... maybe that's also an incentive for them. You could try screed giant as they sell most things screed related.

 

[Ajax123]

They're not cheap

 

[judge]

I've always used the hair hygrometer as instructed by yourself Alan ,so I know it's being used correctly.being incorrectly callibrated worries me a bit.mine must be three years old by now.probably used around fifteen to twenty times .time to start looking in the carbide bomb test I think.cheers

 

[judge]

They're not cheap

Does santa have them on his list

 

[Ajax123]

Only for good boys and girls....

 

[Glynn]

The Carbide method is supposed to be the best method for accuracy, but who has the ba##s to drill, or chisel, into a screed which has under-floor heating pipes running through them. At Tilemaster we have ten electronic moisture meters (Tramex CME4) which are distributed through the sales and technical people and these have been used on hundreds of anhydrite screed floors for the last four years and we have never had a failure when using these meters. People will say they are not suitable, we at Tilemaster disagree and we have total faith in these meters. There is no waiting three days for a reading, it is instant. These meters are not cheap, about £350 but should be part of your tool box. We don't get involved in the debate with the chemistry of moisture, at the surface, migrating, evaporation ect we just trust these meters to tell us wet or dry.

 

[hmtiling]

I've seen bal do on site tests with a carbide bomb just taking a bit from the surface. I'd trust my hygromaster over that any day

 

[Ajax123]

The Carbide method is supposed to be the best method for accuracy, but who has the ba##s to drill, or chisel, into a screed which has under-floor heating pipes running through them. At Tilemaster we have ten electronic moisture meters (Tramex CME4) which are distributed through the sales and technical people and these have been used on hundreds of anhydrite screed floors for the last four years and we have never had a failure when using these meters. People will say they are not suitable, we at Tilemaster disagree and we have total faith in these meters. There is no waiting three days for a reading, it is instant. These meters are not cheap, about £350 but should be part of your tool box. We don't get involved in the debate with the chemistry of moisture, at the surface, migrating, evaporation ect we just trust these meters to tell us wet or dry.

I too use a hand held electronic meter but as a survey tool. With long experience you get to be able to interpret what you see and I can predict a wet or dry result using this. However I would never rely on it solely as I would be putting myself in an impossible position where things to go wrong. I am not sure which meters you are using but I would be very interested to see the test data supporting it. It has lingbbeen claimed by both the major players in the electronic measuring market that they have machines that work but sadlynj learn that are supported either by robust test data or by the british standards I am not able to recommend them.

As for breaking out samples these should be taken at points where there is reliably no heating pipes present. Drilling should be avoided unless the resultant dust can be pushed back into the hole and left to acclimatise for 48 hours and that dust then tested. I usually take samples from points around the edges or where kitchen islands and units will go ensuring thatbthenmeter sample is from the full depth of screed. I have never had a problem hitting pipes all the time iv'e been doing it. The pipes are also much more robust than you might thimk. If there is doubt that the screed is dry based on the electronic meter I don't test... It's a waste of time.

It's also worth noting that moisture accuracy is far less of an issue when using gypsum based materials on top of gypsum based substrates. I have known gypsum adhesive used when the screed is only a week old with no UFH and it's still there to this day nearly 9 years later.

I suppose, putting standards and test data to one side, as long as the test is applied accurately and consistently such that repeatable results are obtained and these can be measured against a scale of results it matters not what test is used.

 

[Dumbo]

I too use a hand held electronic meter but as a survey tool. With long experience you get to be able to interpret what you see and I can predict a wet or dry result using this. However I would never rely on it solely as I would be putting myself in an impossible position where things to go wrong. I am not sure which meters you are using but I would be very interested to see the test data supporting it. It has lingbbeen claimed by both the major players in the electronic measuring market that they have machines that work but sadlynj learn that are supported either by robust test data or by the british standards I am not able to recommend them.

As for breaking out samples these should be taken at points where there is reliably no heating pipes present. Drilling should be avoided unless the resultant dust can be pushed back into the hole and left to acclimatise for 48 hours and that dust then tested. I usually take samples from points around the edges or where kitchen islands and units will go ensuring thatbthenmeter sample is from the full depth of screed. I have never had a problem hitting pipes all the time iv'e been doing it. The pipes are also much more robust than you might thimk. If there is doubt that the screed is dry based on the electronic meter I don't test... It's a waste of time.

It's also worth noting that moisture accuracy is far less of an issue when using gypsum based materials on top of gypsum based substrates. I have known gypsum adhesive used when the screed is only a week old with no UFH and it's still there to this day nearly 9 years later.

I suppose, putting standards and test data to one side, as long as the test is applied accurately and consistently such that repeatable results are obtained and these can be measured against a scale of results it matters not what test is used.

Made your chuckle your opening on this as my brother in law is in the building remedial repair business specialising in waterproofing and damproofing and he is a great believer in how you interpret the results of a reading as to what exactly what the problem is .