I have been laying some glass wool-type loft insulation. 1970s bungalow.
Question: If I board over the insulation, will this give a more effective insulation, compared to just leaving the insulation laid between the rafters? The baedroom in particular gets cold in winter. So I am considering boarding over the insulation in that area with chipboard.
Bruce
Not if it compacts the insulation forcing the air out of it. This will make it worse. Why not just put more insulation down ? If you want something to walk on use narrower Kingspan sheets that fit through loft hatches screwed onto the joists but mark with paint where the joists are as places to stand.
Yes providing you don't compress the insulation any. ideally you want to put an extra layer of rockwool insulation over what you've already put down but at 90 degrees angle so the ceiling joists are also covered up. this will increase your insulation much more than just boarding over it.
Steve
Yes.
Do it, and add as much extra insulation and in particular seal gaps with anything you can find - windproofing makes a HUGE difference.
Thanks. There was a manky, thin layer of insulation down. The previous owner left 4 rolls of insulation in the loft,so I just used these to put another clean, thin layer on top. There are now two, thin, loose layers of insulation down. Boarding over will not compress it.
Adding an extra board layer in this way must logically be a way to improve thermal insulation.
bruce
The insulation value of chipboard is negligible. Best to take a silicon guns and go all over the loft and seal up all gas: pipes, cables through to roses, etc. Make sure the edges of the ceiling is air-tight. Get 4"x2" and lay these across the joists. Pin with a large screw at each joist joint. in the gap fill with "Rockwool", put chipboard over. In area where there is no boarding pile the insulation vet high: 400mm
It is worth doing this in a bungalow as the ceiling is the largest area of heat loss.
Ah, I see, draughts through small gaps need eliminating as a priority. The "thermal mass" of the whole ceiling doesn't leak heat so much.
Sounds equivalent to putting in a new floor level. But its liek you say. since moving in to the bungalow I have noticed the missing thermal insulation effect of having another storey above you.
Bruce
How many 400mm high vets do you know?
At any rate, 400mm of insulation is an unnecessary overkill.
Generalisation. It depends on the size of the bungalow and insulation of the walls if any.
The correct thing to do is to make a heat loss calculation for the house as a whole and look at appropriate and in context amounts of insulation for each surface.
You haven't a clue.
Not a generalisation.
He is doing the loft. It is best he packs in as much as he can. 400mm minimum, in places where he can.
I already showed you the calculations at least twice, and that was for
300mm insulation vs 200mm. 400mm vs. 200mm is simply stupid and will make negligible difference in the context of the house as a whole.I would suggest seeing that 400mm high vet if I were you. They are familiar with diagnosis when the patient is unable to articulate what's wrong with them.
Flawed calculations. Payback time on Insulation levels cannot be pinned down, as fuel prices keep rising. If someone fitted their house out with
400mm in the loft and 300mm in the walls just before 9/11, his payback would have been a year or so. One thing is certain, oil prices keep rising. You also had the inability to view a house for insulation purposes. The upper f loors can be regarded as a bungalow with the largest area of heat loss being the ceiling. Then there is the ability to keep a house cool in summer as it keeps the heat out too. This went right over your head. You see, you just don't know. This is sad.
House prices also keep rising. In many areas, a house with 400mm of insulation may be significantly smaller internally, and hence less of an asset than one with much less or even none. It doesn't take that much of a price difference to be able to pay the heating bills from interest on the difference.
IMM wrote
This is a superb example of utter ignorance and zero experience.
Just adding 3/4 chipboard to a loft many years ago reduced the heating bill by 30%! A small amount of ventilation through a floor is a good thing from a moisture viewpoint. If you are going to board a loft, 8' x
4' sheets cut down to a suitable size to join on the ceiling rafters (close to 8' x 2' is often a convenient size) will not need to be fixed down. This facilitates lifting boards at a later date when she wants the house fixtures just under the ceiling changed around! Loose laid boards float and do not stress the ceiling below when the humidity and temperature changes. If you're going to suffer by boarding the loft, board all of it, don't do half a job with loose insulation floating around. Don't add 4' x 2' joists, unless you're using them supported by the ends, you'll only increase the load on the ceiling rafters unnecessarily.Regards Capitol
Possibly - but in the next part L, the ODPM will probably ask for the equivalent of about 400mm of loft insulation for new houses AND insist that houses are brought up to the regs "where possible" before sale. Just because you don't have a cavity to insulate and so the heat will still pour out there won't exclude you from meeting the requirements where you are able to meet them.
Does this chipbard have magic powers? The insulation value 3/4 of chipborad is neglibible.
More nonsense. Stop making things up.
Use 4x2 joist to increase the depth for more insulation. You must stop making things up.
In an existing house 400mm can easily go in the loft. In a new house the walls can be made to accomodate high insulation levels. Make them hollow and spray in cellulous insulation which also makes the structure air-tight.
No one is saying make each wall 400mm wider, that is silly. Walls can be clad in Kingspan which is high performing and thin. Cavities can be filled. Walls can be externally clad and rendered over or cladding over the insulation.
I expect what happened was there was far too much airflow in the loft and the cold air was permeating the Rockwool and cooling it. Even an airtight blanket would have had the same effect.
This is I suspect the only way these silvered bubble wrap products can work as well.
I did say make the ceiling air-tight.
If one wanted to do the complete and comprehensive job, one would include the energy cost of making and moving the insulating material.
Who is going to put 300mm of insulation in the walls of a 70s bungalow? Get real.
It is very easy to take all of these into account in a heat gain/loss calculation. I know that you have difficulties with simple arithmetic, but the numbers are incontrovertible.
The point is that it is clearly worth putting some insulation in a roof. The question is how much when one also considers the loss of usable space and where it makes sense. The more that one adds, the more the law of diminishing returns applies.
There is little point in reducing the heat loss through the roof from
300W to 200W if there is 5kW going through the walls and windows.
Get away.
More spin and nonsense.
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