Advice about tiling in Spain

[Dumbo]

One of the most bullet proof methods of damp proofing is a cavity drain membrane installed by a quality installer.

 

[Waluigi]

Thank you to everyone who has commented.
Waluigi asked about the humidity reading before the PIV was installed. Unfortunately, the Hygrometer I was using was cheap and nasty and therefore useless. I think I need to get a proper one and saw this one recommended by Heritage House who are specialist in this area and highly critical of damp proof courses. Their website is worth reading - Controlling humidity in houses - https://www.heritage-house.org/damp-and-condensation/controlling-humidity.html I would be grateful for your views on this product.

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I’ve only ever used the Hygrometers supplied with the PIV unit. I’ve seen readings go from 90% to 40% in 3 days. Installed a few of these PIV systems now. All in single skin dwellings where the ‘dew point’ is formed on the inner wall by thermal bridging. PIV’s are a revelation!

 

[Bond]

If you are only experiencing problems in the floor slab and internal walls and not the external walls then, this would suggest you have an effective dpc to the external walls and a lack or defective dpc/dpm to the the internal walls and concrete slab- dampness transferring from the sub-soil area. Lots of good cement based tanking systems on the market. Ground pressure in this situation is unlikely to be very high. You will have to deal with the salts, using an anti-sulphate and perhaps stripping contaminated plaster and re-plastering with a renovating plaster.

 

[WetSaw]

Your house isn't in Camposol is it?

 

[lucius]

Sika do the tanking products, I doubt it is a solid floor normaly block and beam where in Murcia is it.

 

[PaddyW]

I have contacted the PIV company (Flatmaster 2000 | The Complete Ventilation Solution | Nuaire - https://www.nuaire.co.uk/residential/positive-input-ventilation-piv/flatmaster-2000) and they are very confident that condensation is not the problem and that the DPC (which I installed) is the most probable cause. The DPC installer is coming to see the flaky paint and salt problem in about two weeks time. He attributes the problem to salts coming through the newly re-plastered walls and intends to treat it with some sort of acid wash. I must admit that the more I hear about DPCs the more I am not 100% confident. I can just envisage it emerging elsewhere in the property.

I previously mentioned that the bathrooms will be retiled and hopefully that will avoid salt on the grout in these rooms. Can I just ask for your thoughts on the salt on grout in other rooms. Do you think that raking out the grout and re-grouting would solve the problem. Is there any specific type of grout I should use? Should I use anything else in the gaps before filling with the new grout?

As said earlier I am very grateful to those of you have taken the time to help me.
Muchas gracias
PaddyW

 

[Bond]

Following the installation of a chemical DPC it is good practice to remove any plaster which may have been contaminated with mineral ground salts. Apply a anti-sulphate solution and re-plaster with sand and cement or a renovating plaster , to prevent salts migrating to the surface. Some salts have the ability to absorb moisture directly from the air and liquify on the wall/floor surface, the conditions in which this occurs is in cases of high relative humidity.so even in cases where the primary source of moisture has been successfully dealt with, you can experience a secondary form of dampness, if the salts are still present on / within the wall/floor structure.