Loft Insulation

rajanm

Hi everyone,

We have a sizeable loft area which is around 80% boarded up. It houses our boiler and various items like suitcases, etc. The problem is that the insulation is pretty poor - we've been quoted around £2k to clean the loft, board it up and insulate it.

That's a heck of a lot of money for something that, in the main, I think I could do myself.

I feel comfortable with the insulation side of things but I'd have to remove the current boarding.

In terms of ensuring I still have a space to store things, I was thinking I have two options -

1. Keep a small section of chipboarded area intact, even though it isn't well insulated and insulate the rest of the area properly or

2. Take all of the boarding up, insulate it all myself and then get a handyman in to put some flooring in to a section of the loft using loft legs.

Additionally, I have a couple of questions:

What would be the best way to take the existing chipboard up - I'm not entirely sure how it has been installed?

Also what would be the best insulation to use?

Thanks in advance!

Rajan

Mistral001

In option 1. do you mean keeping a small area as it is for storage of suitcases etc. and laying additional insulation on top of the existing boarding over the rest of the area? If you did you could get good insulation and do it yourself in an afternoon for a few hundred pounds.

rajanm

Mistral001 wrote: »

In option 1. do you mean keeping a small area as it is for storage of suitcases etc. and laying additional insulation on top of the existing boarding over the rest of the area? If you did you could get good insulation and do it yourself in an afternoon for a few hundred pounds.

No I mean taking all of the flooring up bar a small area perhaps the square footage of two airing cupboards. That area wouldn't really be insulated and would be kept intact as it is at the moment.

For the remaining 80% of the loft I'd remove the flooring completely and put insulation in. Of course, if I don't need to remove the flooring that would be ideal but my understanding was that you can't put insulation on top of flooring and they it actually had to be stuffed in tightly between the eaves?

Shaun_of_the_Dead

You need to leave suitable access to the boiler.

Davesnave

rajanm wrote: »

For the remaining 80% of the loft I'd remove the flooring completely and put insulation in. Of course, if I don't need to remove the flooring that would be ideal but my understanding was that you can't put insulation on top of flooring and they it actually had to be stuffed in tightly between the eaves?

You will only find out how the particle board is fixed by trying to remove it on one edge, but it would not need to be attached to the joists particularly strongly. It might be nailed, staple gunned or screwed, but with the right tools it should come up quite easily.

You do want it up because the insulation ought to rest on the ceiling as any void between the joists would allow the passage of air. I think you mean this when you say it should be "Tightly stuffed between the eaves." The eaves is the edge of the roof and that's exactly what ought to be left with a small gap at the very edge to allow air to travel into the loft for ventilation.

Under whatever area you have as boarded storage, you could place solid insulation cut to size. That way you wouldn't need loft legs. Solid insulation like Celotex or Kingspan is more efficient than the woolly stuff, so it would still give you a decent amount of insulation. Aim to leave a small air gap above it; it comes in many thicknesses.

FreeBear

Glassfibre and rockwool type insulation should not be "stuffed tightly" into any gap. It needs to have space to fluff up as it is the trapped air that provides the insulation. If there isn't any insulation between the joists, the insulation roll will need to be cut so that it can be gently tucked in to the space - Rolls generally come partially precut for standard joist spacings. If you need something non-standard, use a wood saw to cut the roll while it is still in the plastic wrapping.

One normally use 100mm glassfibre between the joists, and then lay 150mm or 200mm at 90 degrees (uncut). Pay attention to the perimeter under the eaves as this area is often poorly insulated due to the lack of space to work. Some creative thinking may be required.

Celotex/Kingspan boards are great - Expensive, but they have nearly twice the insulating properties of glasfibre/rockwool. Downside is they only come in 2.4x1.2m sheets, so will need cutting to get through the loft hatch. I found a very sharp serrated kitchen knife ideal to cut these sheets. A fine wood saw leaves a rough edge and generates quite a bit of mess. Ideally, joints between the sheets need to be sealed with a squirt of polyurethane foam and then taped with aluminium foil tape (after trimming back any protruding expanded foam).

rajanm

FreeBear wrote: »

Glassfibre and rockwool type insulation should not be "stuffed tightly" into any gap. It needs to have space to fluff up as it is the trapped air that provides the insulation. If there isn't any insulation between the joists, the insulation roll will need to be cut so that it can be gently tucked in to the space - Rolls generally come partially precut for standard joist spacings. If you need something non-standard, use a wood saw to cut the roll while it is still in the plastic wrapping.

One normally use 100mm glassfibre between the joists, and then lay 150mm or 200mm at 90 degrees (uncut). Pay attention to the perimeter under the eaves as this area is often poorly insulated due to the lack of space to work. Some creative thinking may be required.

Celotex/Kingspan boards are great - Expensive, but they have nearly twice the insulating properties of glasfibre/rockwool. Downside is they only come in 2.4x1.2m sheets, so will need cutting to get through the loft hatch. I found a very sharp serrated kitchen knife ideal to cut these sheets. A fine wood saw leaves a rough edge and generates quite a bit of mess. Ideally, joints between the sheets need to be sealed with a squirt of polyurethane foam and then taped with aluminium foil tape (after trimming back any protruding expanded foam).

Do you think that if I manage to insulate at least 80% and leave 20% of the flooring intact as is, that would make a difference or does the whole loft really need to be insulated to the same standard for there to be any difference to the overall heat loss?

FreeBear

The more of the area you can insulate, the better. If 20% can't be done to the same thickness as the remaining 80%, it is still worth doing.