Fitting Underlay

These are some general guidelines to fitting a carpet. Always remember to follow the manufacturer’s instructions and, if in any doubt, use a professional installer.



Use the Right Tools

In any successful carpet, laminate or wood flooring underlay installation it is advisable to have the right tools. You don’t need many but you should use tools specifically for the job.

  • Utility Knife – for cutting the carpet and underlay.
  • Knee Kicker (Carpet Stretcher) – for stretching the carpet over the gripper.
  • Carpet Tucker – for creasing and tucking the carpet behind the gripper.
  • Staple Hammer – for stapling the underlay to timber floors.
  • Hammer – for hammering the gripper nails into the floor.
  • Gripper Shears – for cutting the gripper to the correct length.
  • Tape Measure – a good quality, domestic metal tape measure will do.
  • Knee Pads – optional – depends how strong your knees are!
  • Spirit Level – to ensure the subfloor and the laminate/wood flooring is level
  • Ruler – to ensure the wood/laminate flooring is cut to the correct size
  • Saw – to ensure you cut the laminate or wood flooring properly and square so it fits snuggly
  • Knee Pads, Goggles, Mask – to ensure safety throughout the installation – especially laminate and wood
  • Damp Proof Membrane – to help with moisture protection – if it is not part of the underlay
  • Threshold Strips – to join your carpet, laminate or wood flooring to the next room
  • Laminate Trims – to ensure a quality finish around the room

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Preparation

Good preparation is vital and makes the overall laying of your carpet easier and more sucessful. When laying any type of carpet or flooring the first thing to do is make sure the sub floor surface is smooth, clean and dry. Hammer any protruding nails into wooden underfloors and screw in protruding nail heads. Newly concreted floors and screeded floors must be completely dry. Concrete, asphalt, vinyl, quarry or similar tiles subfloors should have a moisture barrier – and advise buying an underlay that it includes a Vapour stop membrane. For additional protection you could also lay a damp proof membrane first.

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Laying Carpet & Underlay

Many people have never fitted carpet underlay – but in reality it is very simple:

  • Lay the underlay, ideally, so that it runs at right angles to the direction of the floor boards.
  • Lay the underlay so that it overlaps the carpet gripper.
  • Rubber underlay should be laid face down with the rubber on the sub floor and the backing facing up to meet the underside of the carpet. PU foam underlay should have the coloured film facing down on the sub floor and the backing facing up to meet the underside of the carpet.
  • Lay the underlay in strips against each other tightly – but make sure they don’t overlap.
  • Staple the underlay down along the inside edge of the carpet gripper.
  • Trim the excess underlay along the inside of the gripper and use underlay tape to seal the seams. This will prevent lines showing through to your new carpet and stop the underlay moving when you are laying out and stretching the carpet.

Laying the Carpet
A new carpet is a significant investment. If you’re in any doubt on how to install it we strongly recommend you contact a professional carpet fitter. To install a carpet you need to start with a piece that overlaps the edge of the floor by about 10cm. The overlay can be trimmed later so the carpet fits properly. To cut your first section, measure the room at its longest point and add 10 cm to that measurement. Mark the back of your carpet at both edges with that measurement and join the two marks with a line. Fold the carpet over on itself, and using a straight edge and a utility knife, cut through the back of your carpet. Be sure to place a piece of scrap board underneath your cut line to protect the underlying carpet from being cut.

Joining any Seams
If your room is wide enough that you’re going to need another piece of carpet, follow the same process with the second piece – measure, mark and trim. Be sure the carpet pile is running the same way in all pieces, and that the carpet you cut is large enough to overlap the wall by about 10cm, as well as overlapping the first piece of carpet by 10cm. Try to lay out your carpet pieces so the seams won’t be in a noticeable position or in high traffic areas, but obviously sometimes this isn’t possible. Where the carpet pieces will join, overlap the two pieces, and then using a utility knife or a rented seam cutter, cut through both pieces of carpet, ensuring the edges will match exactly. Place a piece of seaming tape (sticky side up) on the underlay where your carpets will join. Use a carpet seaming iron to activate the adhesive (the iron goes on the tape not the carpet) lay the edges tightly together and seal the seam with a roller.

Securing the Carpet
Attach the carpet along one edge. Put the end of the knee kicker about 8-10cm from the wall and kick your knee forcefully into the padded end of the knee kicker. This will stretch the carpet over the carpet gripper, where the pins will grab it and hold it firmly in place. Then using the carpet tucker push the carpet behind the carpet gripper. Work your way around the room stretching the carpet over the carpet gripper, and trim the carpet near the wall with a utility knife or carpet trimmer. At the doorway trim the carpet so the edge will be underneath the closed door and install a threshold bar, which will hold the carpet in place at the doorway section.

Fitting Carpet on Stairs
Fitting carpet on stairs can be awkward but the same principles still apply. Fit a piece of gripper on the tread of each stair so that the angled edge is furthest away from you and also fit a piece on the riser of the next stair so that the angled edge faces the angled edge of the gripper fitted on the tread. Again the gap left really does depend on the depth of carpet to be installed. Three quarters of the depth of carpet is the correct gap. If in doubt try it on one stair. Cut the underlay in strips off of the roll about 5mm narrower than your stairs. Starting at the top stair fit and staple the underlay to the stair tread and over the nose down to the next piece of gripper and cut off with a utility knife. Repeat all the way down. Measure the width of the stairs and cut the carpet from the length of the roll. Roll the carpet up so that the outside is facing you, then fit from the top stair down tucking into the gripper recess on each stair, ensuring the carpet is pulled tightly over each nose. Cut off any excess carpet.

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Laying Laminate/Wood Flooring & Underlay

Laminate flooring is becoming more popular every day, and there are many good reasons to buy it. Once the choice has been made between the different styles, materials and finishes then the next stage is to ensure that the laminate flooring is installed correctly. These are some general guidelines to fitting a laminate floor but each laminate floor manufacturer can have specific installation requirements, so it is important to follow the manufacturer’s instructions where appropriate and, if in any doubt, to use a professional installer. However, fitting it is not hard and these general guidelines are intended to help you get started.

  • Measure out how much you need and make sure you’ve selected the right type. You should make sure that the underlay extends up the wall by at least 5cm.
  • Make sure everything is dry, clean and smooth. On concrete, lay the underlay with the vapour barrier side down and tape the seams of the underlay on the top side with vapour tape.
  • On wooden and other types of floor lay the underlay with the rubber side down, and again tape the seams with an appropriate underlay tape.
  • When fitting the underlay leave a 5-10mm gap around pipes.

Laying the Laminate/Wood Flooring

This stage may vary depending on which brand of flooring you buy. However, the basics are the same. Start on one side of the room and work towards the other, placing spacers along each wall. It is usual to work from the left side to the right as it is easier to click the boards together.

Place your first laminate floorboard down and make sure it is square with the wall, and with the short tongue against the wall. You are going to fit a long thin strip from left to right across the wall facing you, so line up the short end of the next board and click it into place by lining the short tongue of the second board into the long tongue of the first board at about a 30 degree angle. Quick tip – place a spacer where the two boards join, this will help to make sure your first row is straight.

Keep going to the end of the wall on the right. You will probably have to cut the end of the last board to fit. To do this, turn it round 180 degrees and lay it next to the previous board. Make sure there is a spacer between the last board and the wall, and then draw a line across the last board level with the end of the previous board. Cut across this line, turn the board round, and click into place. If you have between a third and two thirds of a board length left then it can be used to start the next row; otherwise, cut a board in half.

To start the next row, put the cut end against the left hand wall (with a spacing wedge, of course) and angle the long edge of the board into the row that is already down. Press forward and fold down at the same time to click it into place. Add the next board’s short edge into the previous board. Once the short edges have clicked into place, angle the long edge against the row that is down and push until the long edges are together, then push the boards down.

For the final row, you might need to cut the boards lengthways to make them fit. To cut the final row to size, place the board to be cut exactly on top of the last full row. Now use a third board on top which is pushed up against the wall (with a spacing wedge). Mark the edge of that third board onto the board sandwiched below it. The mark on that board is where you need to cut. Make sure it is the right way round so that the grooves will click together. When finished remove all the spacing wedges.


Finishing the Trim

If you have taken off your skirting boards then you can refit them now above the laminate floor. This will cover the expansion gap. If you are using laminate flooring trim, then measure and cut the trim. Try to make sure cuts are at exact angles, such as 45% when butting together in corners. Apply trim adhesive to the back of the trim which will go against the wall or skirting board – DO NOT GLUE IT TO THE LAMINATE FLOOR . Press the trim into place, and if needed keep them in place while the glue sets using something heavy. Laminate flooring remains porous even when laid, so it will experience normal expansion and contraction as humidity and temperature levels vary. For this reason you should leave a small expansion gap between the edge of the room and the laminate.