Insulating Your Roof and Loft

The most common way that heat escapes from your house is through the roof. In a home that is not insulated, approximately 25% of heat escapes via the roof. The most effective way to combat this problem and lower your energy bills is by insulating your roof, attic, or loft. The process is very simple and can be done by anyone who is willing to learn.

Insulation is normally effective for 40 years at least and over the course of those years it will pay for itself time and time again.

If you already have insulation in your loft you should still check to make sure that you have enough insulation installed to retain the most heat and save the most money. If each home in the UK had 270mm of insulation in their loft we would save approximately £500 million and reduce 2.7 million tons of carbon dioxide output each year, which is equivalent to reducing approximately 100,000 cars from the road.

How to choose loft insulation

The type of insulation needed will vary depending on the type of loft you have.

Regular Joists and Easy Access lofts

If you have a loft which is easy to access and does not have condensation or moisture complications, it should be rather easy to insulate by yourself. You will start with rolls of insulation made out of mineral wool. The first layer of the mineral rolls will be placed between the joists, covering the horizontal beams on the floor of the loft. Once that is complete, add another layer cross-laid to the previous layer to cover the joists to ensure the insulation is at the depth required. This process should be quite simple for the average handyman; however, if you think it looks difficult you may want to hire a professional insulation installer.

Lofts Used for Storage and Living Areas

If your loft is used as a living area or for storage, you will want to place the support boards over the joists before you begin to lay the insulation. You need to insulate more than just between the joints as that will not have enough thickness.  To install enough installation you can:

  • Purchase floor boards with insulation pre-installed to make the job easier.
  • Use mineral wool to insulate in between the joists and then place strong insulation boards on the top. Cover that layer with more wooden boards.
  • Raise the floor level and install more mineral wool; making sure it is beneath the new level of the floor.

Whatever you decide, it is important that you do not squish the mineral wool while you install boards on top.  This will reduce its insulating ability.

If you plan on using your loft as a living area, you also have the option of insulating the roof rather than the floor. You will need insulation boards that are rigid cut to the correct width so that they will fit tightly between the spaces in the rafters. Once those are installed you can cover them with plasterboard. Since rafters aren’t very deep, you will want to insulate over the rafters with insulated plasterboard to get the best performance. If there is not enough room to insulate over them, you should use the insulation board that has the highest performance rate available to ensure you have enough insulation.

Lofts with Access that are Difficult

If you have a hard-to-reach loft, you may want to consider having a professional install the insulation. Professional installers have the special equipment necessary to install blown insulation which is fire-retardant insulating ingredients made of mineral wood or cellulose fiber. The installation will only take a few hours.

Lofts with Irregular Joists

If the shape of your loft is irregular, usually the problem is that the joists are too far apart for mineral wool.  Another problem may be that there are other obstructions keeping you from laying insulation properly; loose-fill insulation can be used in this case. This can be purchased as vermiculite, cork granules, or cellulose fiber which is usually installed by directly pouring it between the joists until the correct depth is reached. This type of installation may be done via the average handyman but again, if you feel uncomfortable you should hire a professional.

Lofts with Flat Roofs

Flat roofs should always be insulated from above if possible. You can add a layer of insulation board to the surface that is on the top of the timber roof or on the top of the roof’s weatherproof layer. This installation would best be done when you need to replace the roof covering anyways. With recent building regulation codes you will need to make sure that you follow building regulations when replacing a flat roof.

Flat roof jobs are usually left to professionals. Many things can go wrong and while it is possible to insulate underneath a flat roof, condensations problems can occur if the job is not done properly.   The cost of the professional will likely be worth the investment. Insulating a flat roof can save you approximately £180 while also reducing carbon dioxide (about 800kg) per year, possibly more depending how much of the loft consists of a flat roof.

Lofts That are Damp

Insulation, by its very nature, makes spaces cooler.  This can cause problems in an already damp loft. If you have condensation problems or dampness in your loft you should contact a professional before making any changes. Insulation may make the problem worse.

Insulating Hatches, Pipes and Water Tanks

When you insulate your loft between the joists you will definitely keep the house warmer; however, you will also make the space about the insulation colder. If there are water tanks or pipes in that area, it is best to insulate them as well as they are more apt to freeze. Make sure you have something safe to walk around on when insulating in hard to reach areas of your loft.

Cool air in your loft that is insulated means that cold drafts may be escaping or coming from the hatch of the loft. In order to prevent this, consider installing strips of draft-resistant material that are located around the frame edges and install an insulated loft hatch.

Professional Insulation Installers

To get a list of professional installers:

  • Go to the National Insulation Association’s website
  • Place a phone call to your local Energy Saving Trust center at 0800-512-012.
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