I was impressed with some of the technical understanding in this forum so wanted to put my question here. The plan is to put limestone tiles into my kitchen. The project is a large renovation and I dont have some of the major pressures as we do not live in this house during the project. Some background: This kitchen area 3.5m x 6.6m (23m2). The subfloor was concrete (old) over which a poly water barrier was laid then 20mm of kingspan insulation, then another layer of poly water barrier, then UHF pipes stapled to the insulation in 2 circuits (1 zone) fitted (spiral in and spiral out patern) 150mm apart. There is an expansion barrier fitted around the perimeter, then 40-50mm of Gyvlon Thermio screed was pumped into the area (the whole of the ground floor also). The screed was poured in early July and the house was then completely closed up for 7 days with no foot traffic, then the house then was opened daily for the rest of the summer. The laitance was not removed at this stage.
The screed sat in that condition for 80 days before the UFH boiler was turned on. The lowest temperature on the manifold mixing valve is 35C and the UFH run for 4 weeks with constant 35C water through the circuits with the house air temperature at 28C and then the thermostats were commissioned. Each zone has a thermostat probe in the screed ensuring the screed never goes above 27C and the air temperature is set to 19C. The use of low temperature UHF water temperature (35C) was the plan hence very close pipes in the install. During this final phase the with thermostats enabled the water was raised slowly to 45C and slowly back down as well over a period of 2 weeks. I think my substrate is in good condition and dry. I have tried the stick plastic sheet down trick with no sign of moisture.
We are now ready for floor coverings and have chosen large limestone tiles for the kitchen area as mentioned. Here come my questions. The laitance now must come off and it was my plan to do that with a large hand held belt sander with a 40 or 60 grit belt attached to proper dust extraction. Will the belt sander be sufficient? I need to prepare that in advance for the tiler.
Many recommend the use of a decoupling layer. The tile company (Stratford Tiles) from where I purchased this limestone have a lot of experience with the product (they import it) and say the decoupling layer is not a must but is belt and braces so it is a risk call. My substrate looks to be good and it seems like it is commissioned pretty well and there are no cracks in the floor. The decoupling layer is a lot of extra cost (product+adhesive+fitting) so is it really required?
I understand the need for the primer and that will be done properly and I think that must be one suitable for the adhesive chosen. That is where the next variation of opinion comes. Some say a cementitious adhesive whereas other say a flexible adhesive. The tile supplier recommends an S2 type adhesive. I have watched BAL's youtube moisture test and recommendations for a similar screed and they recommend their 'Stone and Tile PTB' which is a flexible pourable thick bed adhesive. What recommendations should I follow?
Thanks in advance for your ideas and help.
The screed sat in that condition for 80 days before the UFH boiler was turned on. The lowest temperature on the manifold mixing valve is 35C and the UFH run for 4 weeks with constant 35C water through the circuits with the house air temperature at 28C and then the thermostats were commissioned. Each zone has a thermostat probe in the screed ensuring the screed never goes above 27C and the air temperature is set to 19C. The use of low temperature UHF water temperature (35C) was the plan hence very close pipes in the install. During this final phase the with thermostats enabled the water was raised slowly to 45C and slowly back down as well over a period of 2 weeks. I think my substrate is in good condition and dry. I have tried the stick plastic sheet down trick with no sign of moisture.
We are now ready for floor coverings and have chosen large limestone tiles for the kitchen area as mentioned. Here come my questions. The laitance now must come off and it was my plan to do that with a large hand held belt sander with a 40 or 60 grit belt attached to proper dust extraction. Will the belt sander be sufficient? I need to prepare that in advance for the tiler.
Many recommend the use of a decoupling layer. The tile company (Stratford Tiles) from where I purchased this limestone have a lot of experience with the product (they import it) and say the decoupling layer is not a must but is belt and braces so it is a risk call. My substrate looks to be good and it seems like it is commissioned pretty well and there are no cracks in the floor. The decoupling layer is a lot of extra cost (product+adhesive+fitting) so is it really required?
I understand the need for the primer and that will be done properly and I think that must be one suitable for the adhesive chosen. That is where the next variation of opinion comes. Some say a cementitious adhesive whereas other say a flexible adhesive. The tile supplier recommends an S2 type adhesive. I have watched BAL's youtube moisture test and recommendations for a similar screed and they recommend their 'Stone and Tile PTB' which is a flexible pourable thick bed adhesive. What recommendations should I follow?
Thanks in advance for your ideas and help.