Differing floor levels

[camel307]

Hi guys,

So.....dining room is at the back of the house, leading on to the kitchen and then the hallway.

Dining room floor is currently 30mm higher than the rest of the downstairs. Plan is to tile right the way from front door to dining room (which provides the back door).

After what seems too much effort I have eventually removed the dining room tiles. Underneath I have found what looks like a concrete (sandy with small stones) sub layer which seems to be coated with a very thing black layer. The sub layer is roughly 30mm thick. Please see pics.

Under the sub layer, there just seems to be sand??? Is this correct?

As I plan to make the downstairs all one level I was wondering if you guys would recommend breaking it all up and starting again. Not only will this allow me to achieve the same level but it will also mean that I will not have to scrape this TOUGH adhesive off of the floor.

Also, for the concrete sub layer, what would you recommend in terms of:

i) Under base - i.e. hardcore or just sand?
ii) What thickness
iii) What kind of mix?
iv) Should I just make the concrete up to the final desired level or leave it a few mm short and then use some latex self levelling compound?

Any help much appreciated.

Please see pics as this might help decipher some of the above.

Thanks again.

Untitled

• camel307
• 22 Dec 2013
• 2

Untitled

• camel307
• 22 Dec 2013
• 2

Untitled

• camel307
• 22 Dec 2013
• 2

 

[stuart45]

You could break up the whole floor and put in insulation as well as a DPM.
A concrete floor with a sand/cement screed finish is quite common.
Depends how much time and cash you have.

 

[Blagard]

As stuart45 has said the old floor does not have a DPM, nothing new about that in old houses.

I would definitely break it out and relay a new floor if the opportunity presents itself. The link below should help. The concrete slab design varies according to size but 100mm is the minimum thickness

It is at times like this when you want to think about the possibility of under floor heating as well.

http://www.sustainablebuildingsolutions.co.uk/solution-data-sheets/ground-floor-retrofit-solid

 

[camel307]

Hi Guys,

Thanks for the reponses. Both are very helpful.

The house is a mid - late 70's house and the dining room looks like a bit of a self build extension at the back of the house. The overall quality is not great.

Both have mentioned a concrete slab but as far as i can tell (without any real digging apart from as shown) the screed (at least i think its screed???) has just been put down on sand. Is this likely or even possible?

Thanks again

 

[stuart45]

Nothing really surprises me in the trade, but in the 70's a normal floor would have been hardcore base, covered with sand to protect the plastic DPM, and then 4 inches of concrete, covered with a sand/cement screed.

 

[camel307]

Although I think its just screed on sand, it is quite weird that no tiles have cracked over time etc etc

Is re screeding a floor easy enough for a competent DIYer?

Also, would you concrete below the required level and then make up the shortfall with self levelling compound? Is the self levelling compound easy enough to remove in future years should I decide to change tiles etc.

Thanks

 

[seasickstevie]

If you're digging up the floor, use the opportunity to get some decent thermal insulation down.

 

[seasickstevie]

And underfloor heating ...

 

[camel307]

I have broken the floor and found that 25% of the floor is screeded over on sand and the rest is on concrete.

So I need to concrete the area that is not concreted. But how should I make up the height?

I can either rescreed or put a DPM over the concrete, add some thin insulation and then plywood (screwed into the concrete). Any one any opinion on concrete, DPM, insulation and then plywood?

Thanks guys

 

[seasickstevie]

If the existing concrete has got a DPM beneath it, you won't need another DPM on top of it.

How much depth is left above the concrete?
Is there enough for insulation (at least 50mm) and a screed?

 

[camel307]

I cannot tell if the existing floor has a DPM beneath it. This is why I considered laying another, just in case not.

There is not 50mm so I suppose the idea of insulation is removed.

However, I am still keen to line the floor with ply wood. I imagine this will offer some heat transfer prevention and will also be easier for me to do than screeding. It should also be perfectly level and flat.

Thanks