Installation of Liquid Screed

Thermotech operate throughout most of the UK although not quite Land's End to John O'Groats!

Dealing with the leading suppliers of liquid screed - Cemex Supaflo - Lafarge Gyvlon - Maxit Alpha - Tarmac Truflow - we are able to meet pumped screed requirements throughout most of the UK. As liquid screed is pumped into a location, it is possible to place it on site into areas that would be almost impossible with a conventional screed.

Unlike many operators, we operate our own screed pumps and we can offer liquid screed across a wide range of projects from relatively small residential single projects up to large commercial or industrial developments.

What is Underfloor Heating Screed?

There is no such thing as underfloor heating screed as an individual or specific screed product. Yes, along with others we refer to "underfloor heating screed" but really we should say "screed for underfloor heating".

All of the liquid screeds mentioned above are ideally suited to underfloor heating screeding due to the characteristics of the gypsum based screeds. In particular their greater strength allows for screeding at a reduced depth, compared to traditional sand / cement screed, whilst maintaining the strength of the screed. Typically you would need a gypsum screed of 50mm when used with underfloor heating pipes, this would eaquate to 50mm on top of the insulation 15/16mm for the pipe on top of the floor insulation with a 34/35mm covering on the underfloor heating pipe itself. Generally, when specified with underfloor heating, a sand / cement screed would need to be 75mm in depth.
Therefore using a gypsum liquid screed reduces the amount of screed required and more importantly it means less screed on top of the underfloor heating loop resulting in a more responsive heating system. In addition there may be construction benefits from the saving in headroom.

Schluter systems have developed a low height system for underfloor heating which was designed to be incorporated within existing buildings where headroom was at a premium. This system, Schlüter-BEKOTEC-THERM, of underfloor heating can only be used with a liquid screed due to the special properties needed.

Thermotech have years of experience in underfloor heating as well as liquid screed and all of our liquid screed operatives are familiar with the problems that can arise when underfloor heating loops are being screeded. As such they able to offer guidance to the site manager should they spot a potential problem with the heating loops and, more importantly, are careful not to cause damage to the loops when laying the screed.

Flowing Floor Screed with Underfloor Heating

The following photographs show a typical installation sequence, in this case with underfloor heating.

Using liquid floor screed with underfloor heating - place your mouse over the image for a description.

Surveying the site to establish levels prior to installation. Laying the edge insulation to comply with building regulations Document L (conservation of fuel and power) Document E (sound insulation). Minimising heat loss from floor slab to wall and to isolate the floor slab from the wall acoustically, to prevent transmission of sound. Starting to lay the floor insulation - note the staggered joints in accordance with manufacturer's recommendations. The insulation covered with a vapour barrier taped into place. Cleaning the surface of the vapour barrier to ensure a positive adhesion of the clip rails. This type of fixing minimises the use of the staple type pipe retainers, as repeatedly puncturing the vapour barrier and insulation can result in subsequent failure and non-compliance with building regulations. Installing the underfloor heating pipe loops into the clip rails. Re-checking the levels and preparing to pump the liquid screed over the underfloor heating loops. Cemex Supaflo liquid screed starting to flow into the area. As the screed is liquid it completely encases the pipework, and by eliminating air pockets found in conventional sand/cement screed increases the efficiency of the underfloor heating system. The finished floor, note the reflection of the ceiling and patio door on the smooth mirror-like finish of the liquid screed prior to drying.