Advice needed, new build basement finishing

[Mat1]

I have a 65m2 "semi finished" basement that I want to finish into a cosy entertainment/living space. I'm in Ibiza where the lowest temperature in winter is about 8degrees and we don't get much rain. The houses in general are never warm.

 

Currently the space is uninsulated but dry and well ventilated. 

 

Some of my neighbours have done amazing looking conversions but none with any internal damp proofing or insulation. It's hard to know whether it's necessary given the climate. It will have heating of course.

 

Currently the plan is to tank the whole thing with Sika damp proof slurry then low profile insulation for the walls and floor. 25mm XPS/PIR for the walls and floor. The XPS will potentially have the UFH built in.

 

Anything I'm missing here?

 

Can anyone suggest any other build-ups for the walls and floor? 

[Conor]

What's the winter time soil temperature where you are? That will largely determine your insulation / heading needs. 

[Mat1]

Hi based on the data I could find I would estimate 8-10C. Similar to the the air temperature at its coldest.

[Mat1]

According to a few sources online it seems it's not strictly necessary to insulate the slab if you're going for UFH. That saves one job.

[Conor]

Those sources are wrong. Never believe randomers on the internet 🤣

 

I don't know how cold it gets there, or what expectations you have, but my first thought would be an air-to-air heatpump. A lot less complex that UFH and will heat the space faster and more efficiently than UFH laid directly on the ground.

 

Is your basement currently completely dry? By adding insulation or other layers, you might actually create moisture problems as the ventilation system could be dealing with any moisture on its own. 

 

If you were to insulate, I'd go for 50mm. 25mm not really worth the bother. How much head height do you have and what are the local building regulations?

[Nickfromwales]

19 hours ago, Mat1 said:

According to a few sources online it seems it's not strictly necessary to insulate the slab if you're going for UFH. That saves one job.

That’s been written by someone in a padded cell, totally bonkers advice 👎
 

7 minutes ago, Conor said:

my first thought would be an air-to-air heatpump. A lot less complex that UFH and will heat the space faster and more efficiently than UFH laid directly on the ground.

Defo the best advice here, even more so if there’s solar PV, but depending on budget and the noise of this running, even electric panel heaters shouldn’t be ruled out. 
 

Is there already a central heating system (gas boiler) in the property?

[Mat1]

2 hours ago, Conor said:

Those sources are wrong. Never believe randomers on the internet 🤣

 

I don't know how cold it gets there, or what expectations you have, but my first thought would be an air-to-air heatpump. A lot less complex that UFH and will heat the space faster and more efficiently than UFH laid directly on the ground.

 

Is your basement currently completely dry? By adding insulation or other layers, you might actually create moisture problems as the ventilation system could be dealing with any moisture on its own. 

 

If you were to insulate, I'd go for 50mm. 25mm not really worth the bother. How much head height do you have and what are the local building regulations?

 

This guy below! Around the 12:30 mark.

 

The coldest months January and February will be about 15C in the day and 8C at night/morning. 

 

We actually have an air source heat pump for the rest of the house. It does heat up the rooms quickly but they also cool down just as fast. I've got it set to 23C now and it's not as cosy as our previous house in the UK. I've ordered a thermostat and temperature gun to see whats happening here. I think we may need an air-air heat pump for summer cooling anyway.

 

Yes it appears to be totally dry at the moment, we get about 45mm of rainfall per month in winter. I have the extraction running most of the day to make sure we don't have humidity problems. Humidity is definitely a problem for a lot of people here

 

Current roof height is about 2450mm but I expect we will lose quite a bit of that for the new ceiling, services etc. I'd be happy with 2200 at the end of everything. No building regs here lol. 

 

 

 

 

 

 

Edited February 23 by Mat1

[Mat1]

1 hour ago, Nickfromwales said:

That’s been written by someone in a padded cell, totally bonkers advice 👎
 

Defo the best advice here, even more so if there’s solar PV, but depending on budget and the noise of this running, even electric panel heaters shouldn’t be ruled out. 
 

Is there already a central heating system (gas boiler) in the property?

 

 

We have this outside

https://www.airconditioningworld.co.uk/midea-m4oe-28hfn8-q-8-2kw-

 

And this inside- 

https://www.ariston.com/es-es/productos/bomba-de-calor/agua-caliente/nuos-evo-a/?keyword=nuos evo a%2B&creative=709892541522&gad_source=1&gbraid=0AAAAADzM6K7Zv4rFcbLtOwZKicV8bOVBB&gclid=Cj0KCQiAq-u9BhCjARIsANLj-s1ejLaxY5GpdQNwlTIVekRkVmGeF12nxFhr34RZAGw287L69X5TZ20aAky-EALw_wcB

 

 

The 3 bedrooms and living area have independent thermostats. I'm not 100% sure how how it all works. Way more complicated than my last house

[Conor]

You could do an experiment. Get a smart thermometer (e.g. meross) set it to log temperature every 15mins or so, hang it off the ceiling at about head height. Get a cheap oil heater, set it on low (750W or so), and leave it on a timer plug  (12hrs a day) for a few days and see what happens.

 

[Nickfromwales]

28 minutes ago, Mat1 said:

 

 

We have this outside

https://www.airconditioningworld.co.uk/midea-m4oe-28hfn8-q-8-2kw-

 

And this inside- 

https://www.ariston.com/es-es/productos/bomba-de-calor/agua-caliente/nuos-evo-a/?keyword=nuos evo a%2B&creative=709892541522&gad_source=1&gbraid=0AAAAADzM6K7Zv4rFcbLtOwZKicV8bOVBB&gclid=Cj0KCQiAq-u9BhCjARIsANLj-s1ejLaxY5GpdQNwlTIVekRkVmGeF12nxFhr34RZAGw287L69X5TZ20aAky-EALw_wcB

 

 

The 3 bedrooms and living area have independent thermostats. I'm not 100% sure how how it all works. Way more complicated than my last house

Ok, so you have a heat source for the UFH, that’s good. 
 

If you do go A2A AC heat & cool then you can get one outdoor unit that will do up to 4 or even 5 indoor units, so maybe kills a few birds with one stone to ditch UFH and go that route. The caveat is, that they’d all be either heating o4 cooling not a mix, if fed off one outdoor unit.