400mm loft insulation

[Mark300zx]

I just had an EPC done which said if I get 400mm deep loft insulation it will increase my EPC to a C. I can't find 400mm deep, so is it just a case of doubling up on 200mm?

[emicen]

Our building warrant specified 400mm;
- 150mm laid between joists
- 150mm perpendicular over the top
- 100mm final layer

[Simpo Two]

Mark300zx said:

I just had an EPC done which said if I get 400mm deep loft insulation it will increase my EPC to a C

Letters are one thing but did they say how much money you're likely to save on heating costs?

My house was built in the 1980s and came with about an inch of ground-up newspaper in the loft! And single glazing. How did we cope?! But then energy was a small part of the household budget in those days.

[Mad Maximus]

Mark300zx said:

I just had an EPC done which said if I get 400mm deep loft insulation it will increase my EPC to a C. I can't find 400mm deep, so is it just a case of doubling up on 200mm?

Yes. In an ideal world you cover the joist height exactly then whole cover for the rest.

150mm joist = 150mm insulation then 250mm (maybe 150 + 100) = 400mm

[bmwmike]

Is this true also for a boarded loft which has 200mm joists beneath 18mm chipboard? There is 100mm insulation leaving a 100mm air gap then 18mm chipboard. I can’t remove the chipboard so sacrificed the storage and put 300mm over the chipboard but the airgap concerns me. It’s a dormer bungalow in case that matters thanks

[Baldchap]

What are you trying to achieve?

Is the house cold? The bills too high? An improvement in EPC for sale? Something else?

[FlyVintage]

Baldchap said:

What are you trying to achieve?

Is the house cold? The bills too high? An improvement in EPC for sale? Something else?

I’m thinking that it’ll be to achieve the upcoming minimum EPC requirement for rental.

[Baldchap]

FlyVintage said:

Baldchap said:

What are you trying to achieve?

Is the house cold? The bills too high? An improvement in EPC for sale? Something else?

I’m thinking that it’ll be to achieve the upcoming minimum EPC requirement for rental.

Gotcha. Then you need to do it.

Loft legs are probably the best answer. You can make the boarding sit higher to allow for more insulation. They're a pain to fit but they do work.

https://www.diy.com/building-supplies/insulation/l...

[LooneyTunes]

Baldchap said:

FlyVintage said:

Baldchap said:

What are you trying to achieve?

Is the house cold? The bills too high? An improvement in EPC for sale? Something else?

I’m thinking that it’ll be to achieve the upcoming minimum EPC requirement for rental.

Gotcha. Then you need to do it.

Unless I have missed it, the change to C is still not locked in.

[TA14]

bmwmike said:

Is this true also for a boarded loft which has 200mm joists beneath 18mm chipboard? There is 100mm insulation leaving a 100mm air gap then 18mm chipboard. I can’t remove the chipboard so sacrificed the storage and put 300mm over the chipboard but the airgap concerns me. It’s a dormer bungalow in case that matters thanks

If you can make sure that the ends are not ventilated then should be better insulated.

[dhutch]

Baldchap said:

What are you trying to achieve?

Is the house cold? The bills too high? An improvement in EPC for sale? Something else?

This!

[Mark300zx]

Trying to get a C rating for rental, although it is not cut and dried for the small amount of money to bump I've decided it's worth a punt!

[Peanut Gallery]

Random shout out to the comment about adding insulation in alternating directions - I thought I could cheat and just keep it between the rafters as I built it up, as it was going to be tucked in between the roof trusses - well thats failed and now the task of trying to get the top layer lifted off, rotated through 90 degrees awaits. Well, it can wait!

[POIDH]

Mark300zx said:

Trying to get a C rating for rental, although it is not cut and dried for the small amount of money to bump I've decided it's worth a punt!

Insulation is the cheapest way you are likely to do this.

[OutInTheShed]

POIDH said:

Mark300zx said:

Trying to get a C rating for rental, although it is not cut and dried for the small amount of money to bump I've decided it's worth a punt!

Insulation is the cheapest way you are likely to do this.

It's not what insulation you actually have, it's what the assessor thinks you have.

LED bulbs and TRVs may be the most cost effective improvement.

[Aluminati]

Peanut Gallery said:

Random shout out to the comment about adding insulation in alternating directions - I thought I could cheat and just keep it between the rafters as I built it up, as it was going to be tucked in between the roof trusses - well thats failed and now the task of trying to get the top layer lifted off, rotated through 90 degrees awaits. Well, it can wait!

Do not block the eaves.

[Mark300zx]

OutInTheShed said:

It's not what insulation you actually have, it's what the assessor thinks you have.

LED bulbs and TRVs may be the most cost effective improvement.

Have already had an unregistered assessment and he advised me to do the above.