Laying hardboard

Laying hardboard on top of wooden floors, commonly floorboards, provides a smooth, flat subfloor for some types of new floor covering. Hardboard is often used before laying carpet, sheet vinyl, and soft tiles such as cork, carpet and vinyl. Hardboard is generally laid smooth side up, especially when floor coverings are to be stuck down, such as with vinyl tiles. Always check which side up a manufacturer recommends for its particular floor covering. For example, some sheet vinyl manufacturers recommend laying the hardboard rough side up. Always take care to find safe fixing points when laying hardboard. A cable, pipe and stud detector will help you here.

Fixing hardboard 1. Stapling is the quickest way to secure hardboard, although ring shank nails (15-20mm ideal and shown here) can be equally efficient. Fix at 15cm intervals.
joining hardboard sheets 2. Butt the second board tightly up against the first sheet. As you place each board keep them as neatly aligned as possible.
nailing down hardboard 3. Work across the room and stagger the joints between the hardboard sheets on subsequent rows until only edge gaps are left.
cutting hardboard 4. Measure and cut pieces for the edges. To cut a straight line in hardboard, use a steel rule and a craft knife. Score the smooth side of the board.
cutting up hardboard 5. Turn the board over, lay the steel rule along the scored line and bend the board up and separate with a craft knife. Fill in all the edges on the floor with cut pieces as required.

Laying hardboard tips

  • For intricate cuts, around the base of an architrave for example, it is worth buying a profile gauge to provide an accurate cutting guideline.
  • Remember that laying hardboard will raise the height of the floor and may therefore effect whether or not doors will be able to open or close. However its best not to trim doors until the finished floor covering is laid.
  • Most of the DIY outlets sell hardboard, but it is not always flooring grade. Therefore you can take a chance on it or you may be better going for a guaranteed option from a specialist supplier.

  1. Ali Jackson says:

    I just had a small loo put in upstairs, with a new combi boiler in it, hence several pipes going into the floor. I want to put hardboard on top of the very gappy floorboards but am not sure how to fit it round the pipes (6 in all) or what tools to use to cut the hardboard. Please can you help
    here’s hoping

    • Hi Ali,

      Firstly, remember to be careful when fixing anything close to pipes. Check and double-check for safe fixing positions.

      Hardboard can be cut with a craft knife (as shown above) or panel saw, should you wish. For cutting holes for pipes, you are probably best looking at my laying a laminate or wood floor guide, with steps 21-24 showing the sort of principles you need to employ.

      Hope this helps,



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