HOW TO PreparE a Floor for Screeding
Floor preparation before screeding
It is vital to ensure that any floor preparation is laid correctly so that your screeding has the perfect base - any errors at this point can mean that your screed may be weaker or crack in future.
Preparing a Floor for Screeding - Checklist:
- Check floor levels
- Install DPM (damp proof membrane) if required
- Lay insulation correctly
- Tape insulation joints
- Install underfloor heating (if applicable)
- Pressure test heating pipes
- Ensure thhe floor is clean before screeding
Plan Your Floor Build Up
What is the overall depth for your insulation, underfloor heating, screed, adhesive/glue and flooring. Bear in mind that you may have to consider any existing door thresholds, adjacent room levels and ceiling heights. If your overall depth is minimal, remember that insulations come in a range of thicknesses, but the U value can remain the same, so still maintain your heat levels. Screeding also comes in a range of depths depending on the specific type - so don’t assume that you must have a 65mm thickness.
Installing the Damp Proof Membrane (DPM)
For a ground floor, make sure that you lay a damp-proof membrane (DPM) usually a 1200 gauge. This will prevent any damp penetrating your flooring from below. The DPM needs to lap at the edges of the walls so that any rising damp doesn’t bridge into the base from the sides. Roll out the DPM and secure around the wall edges with tape. It can be cut down to size once you have finished. Also remember to tape any joints together.
Laying Floor Insulation
Insulations can be cut to size easily with a saw, but it is quite dusty work, so it is advisable to use a facemask or work outdoors. It works best if laid in a brick pattern as it is more unified. Any joints should be taped together.
Installing Perimeter Edging Strip
Edging strips should be laid at the perimeters to prevent the heat spanning into the wall, this is normally 25mm thick. Another point to remember is that this should be thicker than the screeding and is cut down to size afterwards.
Need Advice Before You Screed?
Call us today for freed advice on 0207 099 6264 for expert advise on you your floor build up, underfloor heating, insulation, damp proof membrane and choosing the correct screed
Ensure the Floor is Clean, Level and Stable
Installing Underfloor Heating
The insulation needs to be laid as flat and evenly as possible, any movement at this point will mean that there will always be movement. The movement may cause the screed to crack in future, regardless of its weight, which is heavier when laid wet but becomes lighter once the water evaporates during the drying process.
Walk over the sub-base and see if it is nice and steady - if there is any rocking in the boards put some sand underneath it to even it up. Also have a good look at the existing concrete base when first starting – is it relatively level or sloping at certain points? If so, lay some compacted sand in the worse spots.
If using a liquid screed, a layer of 500-gauge damp proof membrane is required on top of the boards to stop this type of mixture corroding it and to contain the liquid which will seep into any gaps or holes. Again, remember to lap the membrane around the perimeter. The use of a top layer of DPM is only required for liquid systems.
When you are ready to install your underfloor ensure that the pipes are spaced evenly and fixing into place either with specialist pins/clicks or on specially made crating. The ufh system will needed to be tested to ensure it is fully working and pressure tested before screeding on top of the undefloor heating.
Once You Have Followed All These Procedures, You Are Now Ready to Screed!
This is where we come in. Let us know about your project and we can help install your perfect screeding.
We can provide you with superb technical skills matched with experience and extensive knowledge, all at a great price!
So, call us today on 020 7099 6264.
Common Floor Preparation Mistakes
- Uneven insulation boards
- Gaps between insulation
- Untaped DPM joints
- Incorrect edging strips
- Not pressure testing Underfloor Heating
- Debris beneath insulation
FAQS
Why is floor preparation important?
Poor preparation can lead to movement, cracking and an uneven finished floor.
Do insulation boards need taping?
Yes. Taping helps prevent movement and reduces the risk of screed passing between the joints.
Should underfloor heating bee pressure tested?
Yes, pipes should always be pressure tested before screeding begins.
Does liquid screed require additional preparation?
Yes, liquid screed requires a membrane to contain the material and prevent leakage through gaps.
Can I screed over an uneven concrete floor?
Minor variations can often be corrected during preparation, but signiificant level differences should be assessed before screeding begins.
Need Expert Screeding Services?
Call us today about your domestic or commercial project on 020 7099 6264 and we’ll be happy to help.