How Much Insulation Do I Need to Buy?

There are several reasons why it is ideal to order the right amount of insulation the first time round:

  • You only pay one delivery fee
  • The job is completed in one go and the plasterers can commence their work
  • You don’t waste money by purchasing more than you need
  • You don’t have to deal with disposal of excess batts

Calculating Insulation Required for Ceilings and Underfloors

For ceilings and underfloors, you will need to estimate the total area, by multiplying the width by the length. Then multiply this by 0.9, to allow for the fact the timber framing also uses up some of the space in the ceiling or underfloor. The square metre coverage is all you need to know when ordering online with Pricewise Insulation. Simply find the product you need, select the width and required R-value, and as you adjust the number of bags to order, the square metre coverage will update automatically. Make sure you order slightly more than you need rather than slightly less, so you don’t run out of insulation before the job is complete.

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A photo of Bradford Optimo Underfloor Insulation installed under a house.

Calculating Insulation Required for Walls

A similar principle applies for calculating how much wall insulation you need, but with one extra step in the calculation.

  • Multiply the width of the walls by their length to find the total area
  • Subtract the area of the doors and windows from the total area
  • Multiply what is left by 0.9 to allow for timber framing

Measure the Timber Spacings Before Ordering Insulation

Most bulk insulation comes in two standard widths: 430mm and 580mm. The reason for this is to minimise the amount of cutting required by the installer by supplying batts that fit snugly between the most standard timber framing. When ordering insulation make sure you have measured the width between the timber joists so that you can purchase the optimal size. Otherwise you may find yourself having to cut every single insulation batt to make it fit and spending an excessive amount of time and energy completing the job.

Have Everything You Need Before You Start the Job

There’s nothing worse than setting aside some time to complete a DIY project and realising that you’ve forgotten about some minor, but essential equipment. When installing insulation there are a few handy things to have with you that will make the task easier. The most essential tools no installer will work without are a sharp knife and the installer’s stick. While the latter is nothing more than a broom handle (or similar) with a nail protruding from the end, working without one is tedious and totally unnecessary. The stick allows the installer to insert insulation batts easily into hard to reach areas. A step ladder may be necessary when installing ceiling insulation from below and to reach the highest wall cavities more easily.