How Much Insulation In Loft Is Needed?
In a nutshell ……………………you need 300 mm or 12 inches of insulation for maximum savings.
Is Loft Insulation Important?
Loft insulation is very important for all homes in the Uk.
About a quarter of your heat will be lost from your home via your loft. Heat rises and will always try to escape to a colder place.
Once the heat has entered into your loft, it is wasted.
The key is to provide a barrier on the loft floor so that the heat loss is massively slowed down and kept in your bedroom / living room for as long as possible.
We recommend insulation under your bedroom floors for this very purpose to keep the heat downstairs for as long as possible.
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Will Loft Insulation Save Me Much Money On My Bills ?

Yes.
Energy bills will continue to rise year on year and the best way to combat this is to insulate your home properly.
You will only do it once and then continue to reap the benefits for years to come.
How Much Loft Insulation For Building Regs ?
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In previous years just 25-50 millimetres was considered sufficient, and many homes are still at this level.
Building regulations now dictate that every new build needs to have 270mm of insulation in the loft to achieve the required u-value of less than 0.16w /m2k .
This level has been tested and found to achieve the best savings over time.
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Can You Have Too Much Insulation ?
Yes and no.
You can put as much insulation in the loft as you want but 2 things :
- You will be limited for storage
- Any more insulation higher than 300 mm will not give you any more benefit heat loss wise. The calculations have been done scientifically and found that 300 mm depth of insulation will give you maximum savings.
- Adding extra insulation will not be of any benefit to you so you will waste your time and money.
How Much Would It Cost To Insulate A Loft ?
Loft insulation is a relatively cheap energy efficiency measure to install, and you can do it yourself if you are handy for less than £200 !
Having it done professionally would cost you around £600-£900 depending on property size
Grants are available too for Free Loft Insulation if you are on a low income.
What Is The Best Home Insulation For Homes ?
There are many types of insulation you can use for your home to prevent heat loss.
THE BEST INSULATION HOWEVER IS………………….. FREE INSULATION.
This blog will cover all the types of insulation and (IF ELIGIBLE ) help you to get a grant for FREE INSULATION
The most important thing to remember is to ensure your home is adequately insulated to insulate yourself against ever rising energy bills which will eat into your household income on an ever increasing basis.
Insulating your home will prevent heat loss so you will not need to pump in as much heat into your home, costing you a fortune.
Why Do We Need Insulation?
TO SAVE MONEY !!!!!
An uninsulated home will be very cold and very difficult to keep warm in the winter months .You could be wasting up to a third of your heat!
The vast majority of that heat loss (around 58%) comes from your roof and walls so it is very important that these areas are prioritised.
Adding insulation to your walls and roof can reduce your heating costs significantly and there are grants available from the government for people on a low income too.
Typical Heat Loss
Heat loss will depend on your house type but as a rough guide you can expect to lose
- 25% of its heat through the roof
- 33% through the walls
- 15% through the floors
- 15% through draughts
- 20% through windows.
Insulating all of the above is not too expensive either so we recommend you look into this. Most insulation can be fitted by yourself too as it is not rocket science.
How Does Insulation Work:

The sole purpose of the insulation in your home is to slow down (as much as possible) the transfer of the heat from inside your home to outside.
Materials with a low U Value are the best types of insulation .i.e foam based materials are very low U Values and are great insulators.
Insulation works by reducing:
- Conduction, by having very little mass.
- Convection, by trapping air molecules and restricting its movement.
- Radiation, by having just enough mass to slow the transfer of heat by radiation.
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Types Of Insulation Used For Homes

- Rigid Foam Insulation– rigid insulation is commonly used in the walls as they are built, underneath floors and in suspended ceilings
- Wool Type loft insulation – this is the most common form of loft insulation for cold roofs and is typically Fibreglass or Mineral fibre based
- Aluminium foil backed insulation – If your loft area has “warm roof” insulation (insulation laid between the rafters in the roof rather than the joists, this is likely what you have although I also see Fibreglass wool used.
- Multilayer foil insulation – not as common but is used in more specific applications where other forms of insulation may not be suitable.
- Blown In Insulation – for cavities. Usually rockwool or bead
- Foam Spray Insulation
The Best Insulation for Cavity Walls

Traditional Cavity Wall Insulation for homes built from the 1930s onwards uses Blow in Rockwool or bead insulation .
A 25 mm hole is drilled into your walls and the insulation material is blown into the cavity filling all the crooks and crevices.
This insulation is easily retrofitted to your home and takes only a few hours to do.
New builds from The 90s onwards usually have insulation batts fitted as the walls are built. We recommend that you check your walls to see if this is the case as some homes have been missed in the early days.
SEE OUR CAVITY INSULATION PAGE
The Best Insulation for Homes with Solid Walls:
If your existing property has solid walls then your only option is to insulate internally or externally.
- External Insulation – Where you physically add insulation to the exterior surface of your main walls.
- Internal Insulation – As the name suggests, this type of insulation is added to the inner surface of the main walls of your house
You should use a material that is breathable and install a vapour barrier or VCL and an airtightness layer if you want to do it right.
Best Insulation For Homes with Suspended Timber Floors
If your home has suspended timber floors on the ground floor theres a good chance that they’re pretty draughty and uninsulated.
You can add rolls of fibreglass wool between the floor joists held in place with chicken wire or use Kingspan boards cut to size and held up with wooden struts across the joists.
Best Insulation For Loft Insulation
For most homes with a loft we recommend you lay fibreglass insulation onto the floor of the loft to create a barrier to your heat entering the loft. The heat is wasted once in the loft so you should concentrate your efforts on keeping the heat in your bedroom for as long as possible.
A 300 mm barrier of insulation on the floor will achieve this.
If you have a habitable room in the loft we recommend:
- Warm Roof – this type of involves fitting the insulation to the underside of the roof cover (between the rafters) allowing heat up into the roof void hence the name “warm roof”.
- Cold Roof – this type is where you lay the insulation on top of the ceiling of the habitable rooms (or between and on top of the joists).
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See Our Full Index Of Grants On This Website
- FREE FIRST TIME CENTRAL HEATING
- FREE STORAGE HEATER REPLACEMENT
- HEAT PUMP GRANTS
- FREE BOILER / BOILER SCRAPPAGE SCHEME
- LANDLORDS GRANTS
- FREE HOME INSULATION PACKAGE
- FREE LOFT INSULATION
- FREE EXTERNAL WALL INSULATION
- FREE CAVITY WALL INSULATION
Table Of Types of Insulation
Type | Material | Where Applicable | Installation Methods | Advantages |
---|---|---|---|---|
Batts – Rolls & Blankets |
Fiberglass – Mineral wool
Plastic and Natural fibres
|
All Unfinished walls
Suspended Floors and ceilings |
Fitted between studs, joists, and beams. | DIY
Suited for standard stud and joist spacing that is relatively free from obstructions. Relatively inexpensive.
|
Concrete block insulation.
|
Foam board placed on the inside or outside of your walls
Foam beads or air can be mixed in ( at manufacture ) into the concrete mix to increase R-values |
Foundation walls
New construction or major renovations Walls (insulating concrete blocks) |
Insulating concrete blocks are sometimes stacked without mortar (dry-stacked) and surface bonded. | Insulating cores increases wall R-value.
Autoclaved aerated concrete and autoclaved cellular concrete masonry units have 10 times the insulating value of conventional concrete. |
Foam board or rigid foam | Polystyrene – Polyisocyanurate
Polyurethane – Phenolic |
Unfinished walls, including foundation walls
Floors and ceilings Unvented low-slope roofs |
Interior applications: must be covered with 1/2-inch gypsum board for fire safety.
Exterior applications: must be covered with weatherproof facing. |
High insulating value for relatively little thickness.
Can block thermal short circuits when installed continuously over frames or joists. |
Insulating concrete forms |
Foam boards or foam blocks | Unfinished walls, including foundation walls for new construction | Installed as part of the building structure. Cores in the blocks are typically filled with concrete to create the structural component of the wall. | Insulation is built into the home walls, creating high thermal resistance. |
Loose-fill and blown-in | Cellulose – Fiberglass
Mineral (rock or slag) wool |
Enclosed existing wall or open new wall cavities
Unfinished attic floors |
Blown into place using specialist equipment and, sometimes poured in. | Good for adding insulation to existing finished areas, irregularly shaped areas, and around obstructions. |
Reflective system | Foil-faced kraft paper, plastic film, polyethylene bubbles, or cardboard | Unfinished walls, ceilings, and floors | Foils, films, or papers fitted between wood-frame studs, joists, rafters, and beams.
Do-it-yourself. |
Bubble-form suitable if framing is irregular or if obstructions are present. Most effective at preventing downward heat flow, effectiveness depends on spacing and number of foils. |
Rigid fibrous or fiber insulation | Fiberglass
Mineral (rock or slag) wool |
Ducts in unconditioned spaces
Other places requiring insulation that can withstand high temperatures |
fabricate the insulation into ducts either at their shops or at the job sites. | Can withstand high temperatures. |
Sprayed foam |
Cementitious – Phenolic
Polyisocyanurate – Polyurethane |
Enclosed existing wall
Open new wall cavities Unfinished attic floors |
Applied using small spray containers or in larger quantities as a pressure sprayed (foamed-in-place) product. | Good for adding insulation to existing finished areas, irregularly shaped areas, and around obstructions. |
Structural insulated panels |
Foam board or liquid foam insulation core
Straw core insulation |
Unfinished walls, ceilings, floors, and roofs for new construction | Construction workers fit SIPs together to form walls and roof of a house. | SIP-built houses provide superior and uniform insulation compared to more traditional construction methods |