Setcrete Deep Base Floor Levelling Compound goes down thick and sets real quick.
Builders faced with levelling up a significant difference in floor height (maybe up to 50mm) between two rooms – the floor in a house extension and the floor in the original building, for example – would traditionally opt for a sand/cement screed to build up the lower floor level. While this ‘does the job’, there is a better alternative.
Deep base floor levelling compounds can be installed up to a depth of 50mm in one go and, what’s really impressive, is that they can be walked on as soon as 90 minutes after application. Carpets or ceramic tiles can be installed from only six hours after application. Resilient floorcoverings, such as vinyl, rubber or lino can be installed after 24 hours (although if the thickness is above 10mm, it is recommended that the deep base compound is capped with a thin layer (3mm) of high-performance levelling compound or ‘latex’ once it is ‘walk on hard’ and then left for 24 hours).
Moisture menace
Before installing the levelling compound, the subfloor should be checked for the presence of moisture. This can be done using a handheld moisture meter or, more accurately, using a digital hygrometer. You can’t reliably judge the presence of moisture by smell or touch. The maximum moisture level, measured in terms of relative humidity (RH), should be 75 per cent RH or 65 per cent if wood flooring is going to be installed.
Excess moisture is more likely to be present if the subfloor was laid before DPMs became mandatory in buildings, or if it is a newly laid screed and may have high levels of residual construction moisture. The most common cause of floor failure by far is excess moisture. It can attack adhesives, which leads to floorcoverings blistering or becoming detached from the subfloor, causes wood floors to warp, and provides ideal conditions for mould growth.
If excess moisture levels are detected, a rapid set liquid DPM can be applied over the screed, before the deep base levelling compound is installed, to provide a protective moisture barrier. The best performing DPMs will cure in around three hours at 20°C.
Quick and easy
If moisture levels are below the 75 per cent (or 65 per cent) threshold, the deep base levelling compound can be installed immediately, following priming and drying of the appropriate primer. The water-mix power is simply poured onto the area to be raised and allowed to flow into position, requiring only minimal work with a smoothing trowel. The compound will typically have a working time of 20-30 minutes and will be ready to walk on after around 90 minutes.
In contrast, a sand/cement screed used to level up a floor can take a day or two before it is ready to be walked on and, importantly, will take many more days to naturally dry out before a floor covering can be installed. These screeds will typically dry at a rate of around one day per millimetre depth of screed, which would mean around 50 days for a 50mm screed to become fully dry. The temptation is to proceed with the flooring installation before the screed is fully dry, which is virtually guaranteed to lead to problems.
While a rapid set DPM could be applied over the screed to manage moisture levels, a newly laid screed should be left for a minimum of seven days before the DPM is applied. A suitable levelling compound should then be applied before a floorcovering is installed.
Substrate suitability
As well as being suitable for use over sand/cement screeds and concrete, deep base levelling compounds are also suitable for use over non-absorbent subfloors such as ceramics, granolithic, terrazzo, epoxy and polyurethane resins, and ceramic and quarry tiles that are in sound condition and well adhered to the subfloor.
They have found widespread popularity in raising floor levels in conservatory extensions and for filling in trenches in floors where an internal wall has been removed to create a more open living space. Furthermore, they can be used over both wired and wet underfloor heating–systems.
Priming
It is important that subfloors are primed with a suitable primer before applying the levelling compound. Priming ensures good adhesion between the compound and the substrate, providing a higher quality finish. It also helps to prevent pinholing and unacceptably rapid drying of the levelling compound when installed over absorbent subfloors.
Any builder will tell you that anything that cuts down time on a job and makes the installation process easier, while at the same time delivering top notch results is something worth considering. In the case of levelling up subfloors, deep base levelling compounds are certainly in that bracket.
For further information on Setcrete visit https://www.setcrete.co.uk/
