Anhydrate screed prep spec check

[Chalker]

This one!, only joking:lol:

 

[Ajax123]

Hi Alan which machine did you use to achieve 500m2 in 4 hrs as the floors I have done taken a lot longer and I have some decent equipment

Standard STR floor sander with either 60 or 30 grit paper. If the screed is particularly hard e.g. If the Laitance hasn't been removed before the heating has been commissioned if can be harder. In this instance a copper disc could be used instead of paper.

 

[poynton phil]

How dusty of a job is this?

 

[High Peak Tiling]

from Jobs i have done, it is a dusty job but I found most of the dust stays settled instead of airborn.

 

[High Peak Tiling]

I have only used belt sanders.. which took a long time

 

[Ajax123]

I have only used belt sanders.. which took a long time

I have seen belt sanders used and I beleive they do create more airborne dust than rotary str sanders. This is because the belt sanders move faster. They also "skid" over the surface due to them being lighter and if weighted to improve grip can rut the screed. The str sander is best and if dust is an issue you can get one with a integral cpvaccuum function although I see very few of these used.

 

[High Peak Tiling]

I have seen belt sanders used and I beleive they do create more airborne dust than rotary str sanders. This is because the belt sanders move faster. They also "skid" over the surface due to them being lighter and if weighted to improve grip can rut the screed. The str sander is best and if dust is an issue you can get one with a integral cpvaccuum function although I see very few of these used.

When I was on sites near London several years ago I saw the upright sanders being used and they just hoovered up after themselves

 

[Ajax123]

When I was on sites near London several years ago I saw the upright sanders being used and they just hoovered up after themselves

Yup...

 

[Spud]

Alan I have found if there is any moisture in the anhydride that sand paper discs clog and grip the floor causing the rotary machine to overheat, when taking the laitence off of anhydrite floors carborundum stones work far more effectively on a rotary machine and as they have a smaller surface area on damp areas they don't strain the motor or gear box of the machine unnesscesarily
dust is a big issue and we went over to dustless grinding and bagged dust collection I really think saying a 150 m floor can be done in an afternoon with a rotary machine is un realistic but if you have done it then I must be doing something wrong and would appreciate some tips
we have tried several types of machine and spent a fair amount of money tooling up for anhydrite prep work and all floors are different I suppose depending on the product and installers

 

[m3fitter]

spoke to Ardex help desk........... we de scabbed it with a brute, primed it well, and fixed ditra after 3 days......

 

[Spud]

spoke to Ardex help desk........... we de scabbed it with a brute, primed it well, and fixed ditra after 3 days......

How long did the sanding take you and which machine did you use ?

 

[m3fitter]

How long did the sanding take you and which machine did you use ?

the USA don't adhere the ditra to any substrate, thus totally creating a total floating floor, ignoring all substrates..

 

[Ajax123]

Alan I have found if there is any moisture in the anhydride that sand paper discs clog and grip the floor causing the rotary machine to overheat, when taking the laitence off of anhydrite floors carborundum stones work far more effectively on a rotary machine and as they have a smaller surface area on damp areas they don't strain the motor or gear box of the machine unnesscesarily
dust is a big issue and we went over to dustless grinding and bagged dust collection I really think saying a 150 m floor can be done in an afternoon with a rotary machine is un realistic but if you have done it then I must be doing something wrong and would appreciate some tips
we have tried several types of machine and spent a fair amount of money tooling up for anhydrite prep work and all floors are different I suppose depending on the product and installers

The so called "low Laitance" screeds most certainly take longer as the surface is much more consolidated. If it's a proper non low Laitance material the Laitance almost falls off on its own making prep much easier. I agree if it's done too soon the disks can clog up and I know a few guys who have had more success with the carborundum stones. Another dustless option would be enclosed shot blasting with which I have also had some success especially if the screed is contaminated with lignite or similar.

I also find that people sometimes work too hard to open the surface taking off more than they need from the surface. This is another potential issue of the low Laitance screeds as it can be difficult to know when the Laitance layer is actually off. This is another advantage of the non low Laitance stuff as it is pretty obvious when you've got the Laitance off. Laitance should be microns deep, may be up to half a mm... I sometimes get told that a "Laitance" is 10mm deep. This would not be Laitance but a defective screed usually caused by over watering... This can be much more difficult to sand properly.

 

[Ajax123]

spoke to Ardex help desk........... we de scabbed it with a brute, primed it well, and fixed ditra after 3 days......

I can say without a shadow of a doubt that if you have stuck ditra down after three days of the screed being installed using an Ardex system there is absolutely no way on earth that it would still be stuck down after 3months...

 

[Spud]

the USA don't adhere the ditra to any substrate, thus totally creating a total floating floor, ignoring all substrates..

Think we got some wires crossed here ?