Loft insulation question with a view to future conversion....
 

Hi all

I have searched the group via google for info on logt insulation - but
can't really find an answer that fits my question.... so here goes.

Got an old house. Almost zero insulation in the loft. Planning a
loft conversion in a couple of years when the barn conversion is
complete (another story).

Anyway, just measured the rafters in the loft and the dims a

2.5" wide
3" tall
Space between rafters averages at approx 15.5" (some 14, some 16)

I need to put some insulation up there - but don't want to waste money
by putting something down only to find it unsuitable when we come to
convert.

What should I use? Kingspan/celotex? Can I cut it to fit the varying
widths I'd need? If this is the best solution, how do you fit it?

Can I also ask about the loft conversion - woudl the rafters as they
are support another couple of rooms - or would the whole rafter thing
need upgrading (by an expert!)

Thanks in advance

Simon

On Sun, 31 Oct 2004 14:17:50 +0000, Simon Hawthorne
wrote:

Hi all

I have searched the group via google for info on logt insulation - but
can't really find an answer that fits my question.... so here goes.

Got an old house. Almost zero insulation in the loft. Planning a
loft conversion in a couple of years when the barn conversion is
complete (another story).

Anyway, just measured the rafters in the loft and the dims a

2.5" wide
3" tall
Space between rafters averages at approx 15.5" (some 14, some 16)

I need to put some insulation up there - but don't want to waste money
by putting something down only to find it unsuitable when we come to
convert.

What should I use? Kingspan/celotex? Can I cut it to fit the varying
widths I'd need? If this is the best solution, how do you fit it?

Can I also ask about the loft conversion - woudl the rafters as they
are support another couple of rooms - or would the whole rafter thing
need upgrading (by an expert!)

Thanks in advance

Simon

I would worry about standing up there on those rafters.

Will you save enough to justify the cost over 2 years ?

Rick

Simon Hawthorne wrote:
Hi all
snip
Got an old house. Almost zero insulation in the loft. Planning a
loft conversion in a couple of years when the barn conversion is
complete (another story).

Anyway, just measured the rafters in the loft and the dims a

2.5" wide
3" tall
Space between rafters averages at approx 15.5" (some 14, some 16)

I need to put some insulation up there - but don't want to waste money
by putting something down only to find it unsuitable when we come to
convert.

The rafters are utterly unsuitable for anything more than walking
around on carefully, and maybe storage of empty boxes, and will need
replaced or augmented to put rooms up there.

As this is the case, the insulation is unlikely to be suitable - you may
not want to insulate the two rooms off anyway as eventually you'd want
the whole roof to be warm.
Personally, I'd get some 150mm insulation at B&Q or wherever, and
split into three 50mm layers, before laying.
You should probably do some sums to see how much money you'll save
in heating, and how much the insulation will cost over a couple of years.

"Simon Hawthorne" wrote in message
...
Hi all

I have searched the group via google for info on logt insulation - but
can't really find an answer that fits my question.... so here goes.

Got an old house. Almost zero insulation in the loft. Planning a
loft conversion in a couple of years when the barn conversion is
complete (another story).

Anyway, just measured the rafters in the loft and the dims a

2.5" wide
3" tall
Space between rafters averages at approx 15.5" (some 14, some 16)

I need to put some insulation up there - but don't want to waste money
by putting something down only to find it unsuitable when we come to
convert.

Why not insulate the rof and then it will be ready when you install a new
floor for the conversion. Kingspan/Celotex is the right route - you can cut
to any shape with a saw.

But if you leave the conversion too late the new Part L will kick in and
you'll need even more insulation to meet it (and it may even be impossible).

Simon Hawthorne wrote:

I need to put some insulation up there - but don't want to waste money
by putting something down only to find it unsuitable when we come to
convert.

What should I use? Kingspan/celotex? Can I cut it to fit the varying
widths I'd need? If this is the best solution, how do you fit it?

You could go with the insulate the roof option, as has been suggested.
If you want to go for the more conventional approach between the ceiling
joists, then use something fireproof like Rockwool since you can then
re-use it later.

Can I also ask about the loft conversion - woudl the rafters as they
are support another couple of rooms - or would the whole rafter thing

Not a chance....

need upgrading (by an expert!)

Upgrading yes, although you will need someone who knows what they are
doing to design the stucture, implementation may not require much
expertise beyond basic capentry and common sense.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Simon Hawthorne wrote:

Hi all

I have searched the group via google for info on logt insulation - but
can't really find an answer that fits my question.... so here goes.

Got an old house. Almost zero insulation in the loft. Planning a
loft conversion in a couple of years when the barn conversion is
complete (another story).

Anyway, just measured the rafters in the loft and the dims a

2.5" wide
3" tall
Space between rafters averages at approx 15.5" (some 14, some 16)

I need to put some insulation up there - but don't want to waste money
by putting something down only to find it unsuitable when we come to
convert.

What should I use? Kingspan/celotex? Can I cut it to fit the varying
widths I'd need? If this is the best solution, how do you fit it?

Can I also ask about the loft conversion - woudl the rafters as they
are support another couple of rooms - or would the whole rafter thing
need upgrading (by an expert!)

Thanks in advance

Simon


You can either insulate the ceiling joists, in which case we need to
know the dimensions of them, or you can turn your 'cold roof' into a
'warnm roof. which is more than just laying down some insulation stuck
between the rafters.


Not sure what you are really after here.

I'd be invlined to jstslap don thick rockwool for now, and sort out a
warm roof as and when you do the conversion, at which time the old
insulation will get binned anyway.

I need to put some insulation up there - but don't want to waste money
by putting something down only to find it unsuitable when we come to
convert.

If you want to start on the conversion, as it were, you should insulate the
roof with Kingspan.

You will need to decide whether you are going for a ventilated area behind
the insulation, or a full fill.

With a ventilation fill, you leave 50mm between the insulation and the felt.
This area is then ventilated using soffit and ridge vents. You then apply as
much insulation as you can (25mm in your case) and then more underneath up
to 100mm total thickness (75mm). Then foil backed plasterboard over that.
(You can order the insulation ready attached). This is a simple technique,
but can make the roof thicker, which may be a problem for headroom,
especially when you consider that the floor may need to be strengthened
(i.e. made thicker).

The alternative, with no ventilation space required is just to fill the
entire space within the rafters (75mm in your case) and the rest up to 100mm
below (25mm in your case). This gives much more headroom. The problem is
that you loss the ventilation and another method must be used to ensure that
the roof timbers don't rot.

Your two alternatives for this solution:

1. Have no felt (old houses may have no sarking at all. The gaps between the
tiles/slates provide adequete ventilation for the roof timbers). I'm not
really suggesting ripping the old felt out, as it provides a useful backup
when the roof covering fails and is required by building regulations.

2. Reroof, using breathable membrane instead of felt. This allows moisture
to pass through, but still provides weather protection. Unfortunately, it
needs to have all the slates/tiles removed and replaced after installation.
This may be an option if you are intending the reroof anyway.

There is one other solution if reroofing anyway and you have a detached
house and no problems getting planning permission. This is to install a
genuine warm roof. You'd put insulation between and above the rafters. The
rafters than become part of the warm climate below, protected from the cold
and wet outside air. It raises the roof, which might not be aesthetically
pleasing and would create an ugly mismatch on a row of terraced houses.

Christian.

On Mon, 01 Nov 2004 10:20:50 +0000, The Natural Philosopher
wrote:

You can either insulate the ceiling joists, in which case we need to
know the dimensions of them, or you can turn your 'cold roof' into a
'warnm roof. which is more than just laying down some insulation stuck
between the rafters.

Sorry guys - the dims I gave were for the joists - which I meant all
along...... bloody beginners not knowing the difference (sorry!!)

S.

On Mon, 01 Nov 2004 10:20:50 +0000, a particular chimpanzee named The
Natural Philosopher randomly hit the keyboard and produced:

You can either insulate the ceiling joists, in which case we need to
know the dimensions of them, or you can turn your 'cold roof' into a
'warnm roof. which is more than just laying down some insulation stuck
between the rafters.

A lot more. In fact, completely stripping the felt, battens and
tiles, insulating OVER the rafters, then counterbattening over that.

A warm roof is NOT one where any part of the rafters are below the
internal temperature of the building.
--
Hugo Nebula
'What you have to ask yourself is, "if no-one on the internet wants
a piece of this, just how far from the pack have you strayed?"'

"Hugo Nebula" abuse@localhost wrote in message
...
On Mon, 01 Nov 2004 10:20:50 +0000, a particular chimpanzee named The
Natural Philosopher randomly hit the keyboard and produced:

You can either insulate the ceiling joists, in which case we need to
know the dimensions of them, or you can turn your 'cold roof' into a
'warnm roof. which is more than just laying down some insulation stuck
between the rafters.

A lot more. In fact, completely stripping the felt, battens and
tiles, insulating OVER the rafters, then counterbattening over that.

It's more usual to lay OSB over the top of the insulation rather than
counterbattening, as I think is the only way now allowed in Scotland.