Sand Cement Screed to level painted garage floor

[Mosschops72]

Hi All - I am converting my garage and need to level the floor as it slopes by 6cm over the 5m length of the garage. I am going to use a sand cement screed for the job however the existing concrete base was previously painted. Any advice on the best way to tackle this to ensure a decent bond between screed and floor would be appreciated. Can i use a slurry of SBR / PVA, Cement etc ?

Some of the paint has worn over time but id say it is still giving 90% coverage (see pic)

Many Thanks
Andy

 

[noseall]

Forget a s/s screed, it would not work even if you could get a decent bond. It will fail and break up where the thickness reduces.
Is there to be a knock-through from the main dwelling? If so, look at what the differences in height (if any) there is betwixt garage and dwelling floors. It may mean some furrings and ply.

 

[Mosschops72]

Thanks nose, the depth of the screed will be o less than 25mm and up to 65mm, the research I have for suggests 25mm is the minimum accepted depth. This is a detached garage btw.

That’s give more info I am doin g this with building refs and in order the insulate the floor I wanted to level prior to putting down the insulation boards and chipboard as per the spec I have.

 

[Mosschops72]

In fact following more googling it seems there is another option which is to use a framework of furrings and then osb on top with a dpm underneath

 

[noseall]

it seems there is another option which is to use a framework of furrings and then osb on top with a dpm underneath

Really, who would have thought.....

It may mean some furrings and ply.

 

[tomfe]

So no insulation in the floor then? This will not be part of the main house?

 

[noseall]

So no insulation in the floor then? This will not be part of the main house?

BC will overlook floor insulation and other points, regards garage conversions for the sake of cost v's gain of removing a sound floor.

The best case is that the proposed floor is low enough to get some insulation in as well as membrane and wearing surface.

 

[^woody^]

If the floor is having insulation and an new deck on top, then the slab can be leveled in screed as it wont matter if it loosens as it wont be going anywhere.

 

[Tigercubrider]

Most garages have a decent height difference between the original floor and the house

 

[noseall]

Most garages have a decent height difference between the original floor and the house

Not those that have opted for the sloping floor (as opposed to the step down) method of spillage protection, as in the OP.

 

[noseall]

If the floor is having insulation and an new deck on top, then the slab can be leveled in screed as it wont matter if it loosens as it wont be going anywhere.

It could become a nuisance if the OP leaves it a while before covering or bits start to dislodge if he decided to drill and fix battens etc. Otherwise I'd agree.

 

[Mosschops72]

Thanks Woody and Nose, would have been helpful if I had given all the info up front (the dangers of late night posting !)

This is a detached garage and fortunately I have sufficient depth to put down the screed layer to level the floor and then DPM, Kingspan TF70 and chipboard on top of the screed to meet regs, of course I will need to ensure the screed is allowed to dry fully first and be careful not to damage it in the meantime.