Advice about tiling in Spain

[PaddyW]

Running out of options.

I would be grateful for some advice regarding a bathroom refurbishment in Spain. The property is not used for long parts of the year and I have problems of damp and condensation. It has always been difficulty to know whether the flaky walls and salt are caused by damp or rising damp. At the time the house was built (2004), Spanish builders infrequently used damp proof courses. The problem started after 5 years. After years of problems I had a new injected damp proof course installed, air vents installed in every room and a PIV system installed (Flatmaster 2000 | The Complete Ventilation Solution | Nuaire - https://www.nuaire.co.uk/residential/positive-input-ventilation-piv/flatmaster-2000). The PIV system runs 24/7. The walls were replastered by a British company and repainted. Eighteen months later some of the walls near the floor were all flaking again, and salt deposits were on the grout on some of the floor tiles.

This property was to be my retirement home, but I get depressed every time I walk in the door and see the state of the walls and floor despite all the money spent on getting it to look nice.

In the bathroom there has always been some salt in places on the grout. The grout at the moment is about 0.75cm wide. The bathroom is to be completely gutted and new wall and floor tiles laid, and new drainage put in place. I want to ensure that the bathroom has been sealed properly to avoid salt on the tile grout or any other form of rising damp. The builder and tiler have suggested using Gunite which they use to seal swimming pools. The new floor tiles will be pretty close and I don’t know how much grouting will be done this time round.

Any advice on how best to proceed would be gratefully appreciated. I know that products are different in Spain and this may be part of the problem in resolving this problem.

The salt on the grout in other parts of the property is significant but scattered and intermittent but there were small piles about 0.5cm high. Could this grout be raked out and redone to prevent this happening again? Any recommendations on the type of grout or sealant to be used? I should add that the same type of tiles are used on the patio surrounding the property and I have never seen salt outside the house.

I would be very grateful if I could draw on the expertise of users of this forum as I seem to be running out of options.

Thank you

PaddyW

 

[Bill]

Get the Malaga Kid on to it........ @pdc

 

[Andy Allen]

Our English teacher...@pdc is the man to talk to....

 

[Bond]

The presence of salts on the surface would suggest lateral or rising damp as being the cause. Without knowing the structure it’s defficult to give any definitive advise. If possible establish and deal with the cause externally. Internally to the wall surfaces affected by salts, clean down and apply an anti-sulphate solution, and perhaps tank the walls , prior to re-tiling etc.

 

[WetSaw]

Where in Spain is the house?
I assume that you've checked for leaks? Is the water turned off when the house is unoccupied?
Unfortunately it's not uncommon for empty houses to suffer damp problems over here.
I'd have rendered the interior walls rather than plaster as that sucks up even the slightest bit of moisture. The bathroom could be tanked but you must make sure you use a product that is good for negative pressure as well as positive, Kerakoll Osmocem for example.

 

[Wayne Brown]

Sounds like your property could have been flooded at sometime once salt water gets in there then it will always come out somewhere, I had a 3 story townhouse that had been flooded in 1953 and had exactly the same problems as you are experiencing just I thought . Kop

 

[lucius]

Can you get to underneath the floor beams and vent that area? Even if DPC has been used often their is no membrane
In the floor and if the subsoil is getting wet it can cause the problems you are getting.In my part of Spain Sika products are widely available so you can research these in English.Unfortunately what you are experiencing is quite common in Spain but tend to get better once the house is lived in.

 

[Waluigi]

Did you have a Hygrometer Reading before and after the PIV was installed?

 

[PaddyW]

Thank you to everyone who has commented. I am very grateful that you have taken the time to help me.

A number of questions were posed which I will try and answer. The house is in Murcia.

The water is turned of when the house is unoccupied. We recently had a leak in the garden and I now monitor water usage and confirm that there are no leaks.

There is no salt or damage on the exterior walls - just internal walls.

I did not fully understand one of the comments and would like some clarification. "The bathroom could be tanked but you must make sure you use a product that is good for negative pressure as well as positive, Kerakoll Osmocem for example." I know that some products can have adverse effects and I am anxious not to apply anything that could exacerbate the problem.

The house has a solid floor and underfloor inspection is not possible.

Lucius has commented - "In the floor and if the subsoil is getting wet it can cause the problems you are getting. In my part of Spain Sika products are widely available so you can research these in English." What sort of Sika products would be of use to me? I recall that the problem started after a particularly extreme Gota Fria. This is an annual event often associated with violent downpours and storm.

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.

 

[WetSaw]

A lot of tanking ( waterproofing) products are only suitable for positive pressure, as in keeping water in a water tank or swimming pool. What you have is potentially damp coming from below that will contain a lot of minerals etc so whatever you use must be impervious to those. Sika, as someone mentioned, are a good brand with a broad range of products.

 

[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.

View attachment 105093 View attachment 105093

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.