There are 4 basic levelling compounds on the market:

latex - This can be used over most floors without showing any problem, but tends to be weak etc, used mainly by professionals that don't know what there doing!

acrylic - This is a very good levelling compound. dries hard. Downside is that it does not flow very well.

water based - This is also very good. Flows very well and is really hard when dry. Downside is that it does not like moisture in subfloor base.

fibre bonded (water based) - The same as water based but better! Designed to go over floors that flex. Even floor boards!

You should start by finding out if you have a DPM and if your floor moisture content (if a new base) is within british standard of 75% relative humidity. This will make a big difference to the product you use. Water based being a big no no if above 75% relative humidity and the same for most floor coverings, wood, amtico, karndean, lino etc. You also need to make sure the base your screeding over weather it be concrete, tiles, quarry etc is stable and sound.

If below 75% or you have a working DPM:

1. Clean floor from contaminates (polish etc) next take a large straight edge and go over floor and mark out any major low or high spots. High spots should be grinded down (will save on compound) and low spots should be filled with 400 repair mortar, (there will be a link at the end for where to get all products from). Try to get all repairs within 3mm per meter run out. Fill in any cracks/holes etc with mortar
2. Prime with p131 neoprene primer. Neat on non absorbent floors and diluted with water (approx 1-3) on absorbent bases.
3. Choose your screed. I would always say water based unless moister problem in base floor. Water based flows really well and cant go wrong putting it down.
4. make sure you mix as the bag says. Stir with electric whisk until lump free and then tip out onto floor, then trowel as flat as you can. Your not trying to get it level here, just flat and smooth. Don't play with it to long and try to keep above 3mm deep. It will flow easier.
5. make yourself a cup of tea grab a beer , whatever and put the TV on!

If you don't have a DPM or moister content is to high, see How to install a surface DPM and refer back to this where needed.

If your levelling between wood and concrete or just over floorboards, see How to level a very uneven wooden subfloor.

You need p131 neopreme primer Either:

• red bag (water based)
• green bag with 55 acrylic or 114 latex liquid
• 400 repair mortar
• Maybe 700 flex. (for flexible bases)

mattysupra 2007/02/25 16:13