I'm right into the major mess stage with the old Bungalow. It would make
sense to rip out the plasterboard and crappy glass wool that's full of
mouse crap and corpses, and better to do it now and get it over and done.

Some (30% at least) has to come out so I can get access to run cables and
pipes anyway. Ultimately it should all come out so I can check the roof
timbers and reinsulate to a better standard (this dormer isn't freezing but
it does bleed heat).

If I do it now, it will have to run for two winters uninsulated as that's a
phase 2 job.

I could mitigate by dropping 4" of insulation under the floor (like bagged
glass wool or sheeps wool or something else that's not totally offensive to
my lungs).

4" would be a useful long term acoustic barrier, keep a little heat in
downstairs and end up below my cables (clipped to side of joists) so I
don't have to consider silly amounts of derating.

What would you do?

Cheers

Tim

Tim S wrote:
I'm right into the major mess stage with the old Bungalow. It would make
sense to rip out the plasterboard and crappy glass wool that's full of
mouse crap and corpses, and better to do it now and get it over and done.

Some (30% at least) has to come out so I can get access to run cables and
pipes anyway. Ultimately it should all come out so I can check the roof
timbers and reinsulate to a better standard (this dormer isn't freezing but
it does bleed heat).

If I do it now, it will have to run for two winters uninsulated as that's a
phase 2 job.

I could mitigate by dropping 4" of insulation under the floor (like bagged
glass wool or sheeps wool or something else that's not totally offensive to
my lungs).

4" would be a useful long term acoustic barrier, keep a little heat in
downstairs and end up below my cables (clipped to side of joists) so I
don't have to consider silly amounts of derating.

What would you do?

Is anyone going to be living in the dormer during the wait? If not, then
I would go with the insulate the floor option. You will just have to
cope with it being 'kin freezing when you need to work in that space.

The other option may be to get some rigid PIR insulation panels that you
could cut roughly to shape and just push against the sides when you are
not actually working on the space. That would give effective enough
insulation short term if you don't mind it looking like you are living
inside a tin foil box!

--
Cheers,

John.

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

On 1 Dec, 15:08, Tim S wrote:
I'm right into the major mess stage with the old Bungalow. It would make
sense to rip out the plasterboard and crappy glass wool that's full of
mouse crap and corpses, and better to do it now and get it over and done.

Some (30% at least) has to come out so I can get access to run cables and
pipes anyway. Ultimately it should all come out so I can check the roof
timbers and reinsulate to a better standard (this dormer isn't freezing but
it does bleed heat).

If I do it now, it will have to run for two winters uninsulated as that's a
phase 2 job.

I could mitigate by dropping 4" of insulation under the floor (like bagged
glass wool or sheeps wool or something else that's not totally offensive to
my lungs).

4" would be a useful long term acoustic barrier, keep a little heat in
downstairs and end up below my cables (clipped to side of joists) so I
don't have to consider silly amounts of derating.

What would you do?

Cheers

Tim

Rip it out & change Dormer insulation to phase 1?

Phil coughed up some electrons that declared:

Rip it out & change Dormer insulation to phase 1?

Hi Phil,

Unfortunately I can't, although it would be an ideal plan. The Phase 1
schedule is tight (need to have ground floor done and dusted by Sept 2009).

There's going to be complications with how to maintain airflow above the
insulation, which I may need to take paid advice on, unless the BCO is
willing to stick his neck out with an opinion. It really needs to be done
together with new soffits with ventilation strips (the current ones have
none) so I can see it taking quite a lot of research and fiddling around to
get it right.

It's all to do with having 2 dormers right upto nearly the ridge height on a
full hipped roof - no obvious way to maintain a breathing airflow above
celotex other than about 64 vent tiles( at 20 quid each!). There's bound to
be a more sane solution, but it's not one that is likely to be in, say, a
Celotex or Kingspan application guide.

Cheers

Tim

Tim S wrote:

It's all to do with having 2 dormers right upto nearly the ridge height on a
full hipped roof - no obvious way to maintain a breathing airflow above
celotex other than about 64 vent tiles( at 20 quid each!). There's bound to
be a more sane solution, but it's not one that is likely to be in, say, a
Celotex or Kingspan application guide.

One obvious one that springs to mind if you are planning on stripping
any of the roof, is to replace the under tile felt with a breathable
one. Failing that, a ventilated ridgewould probably cost far less than
vent tiles (although 64 sounds like rather alot - one per rafter space
ought to be adequate). You can also get a fair amount of ridge
ventilation just by cutting away 6" of felt close to the top (assuming
you have some soffit vents).


--
Cheers,

John.

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

John Rumm coughed up some electrons that declared:

Hi John,

Is anyone going to be living in the dormer during the wait?

No - it's pegged as "uninhabitable" for Phase 1. Half the floor will be
missing too.

If not, then
I would go with the insulate the floor option. You will just have to
cope with it being 'kin freezing when you need to work in that space.

That's OK - I only have to watch the tanks, but I expect enough heat will
leak up from below to keep them happy, and I can chuck something round them
temporarily.

The other option may be to get some rigid PIR insulation panels that you
could cut roughly to shape and just push against the sides when you are
not actually working on the space. That would give effective enough
insulation short term if you don't mind it looking like you are living
inside a tin foil box!


That's not a bad idea. I need the celotex anyway assuming I go for this,
rather than more wool to a greater thickness ( see other post regarding
ventilation and anti-condensation measures). I could screw it on across the
rafters loosely in whole sheets for the mostpart, then rescue it to cut and
fit later.

Cheers

Tim

John Rumm coughed up some electrons that declared:

Tim S wrote:

It's all to do with having 2 dormers right upto nearly the ridge height
on a full hipped roof - no obvious way to maintain a breathing airflow
above celotex other than about 64 vent tiles( at 20 quid each!). There's
bound to be a more sane solution, but it's not one that is likely to be
in, say, a Celotex or Kingspan application guide.

One obvious one that springs to mind if you are planning on stripping
any of the roof, is to replace the under tile felt with a breathable
one.

Aye - If I were relaying the roof, that's exactly what I would do.

But the roof seems in generally good order and the felt looks like
bitumanised cloth of some sort (black with crisscross stringy bits)

I might ask the builders how much a roof relay would cost - it would be a
useful metric to compare the economics of other solutions against. Have to
watch it though - this is how budgets go wildly out of control ;-

Failing that, a ventilated ridgewould probably cost far less than
vent tiles (although 64 sounds like rather alot - one per rafter space
ought to be adequate).

That is one per rafter space. I must get some pictures of the roof on the
web - needs to be seen to be believed! The problem with the ridge vent idea
is that I don't have any sort of apex under the ridge - dormer roofs are
flat and cut straight in like this:

ASCII Art mode

Side profile:


==========^===========
| / \ |
| / \ |
| / \ |
| / \ |
/ \
/ \
---------------------------

Do you see the problem?

Cheers

Tim

You can also get a fair amount of ridge
ventilation just by cutting away 6" of felt close to the top (assuming
you have some soffit vents).

Tim S wrote:

That's not a bad idea. I need the celotex anyway assuming I go for this,
rather than more wool to a greater thickness ( see other post regarding
ventilation and anti-condensation measures). I could screw it on across the
rafters loosely in whole sheets for the mostpart, then rescue it to cut and
fit later.

Use scraps of ply or something as large washers - stops the screws
pulling through (as I discovered attempting to line the underside of my
workshop roof last week!)

--
Cheers,

John.

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

Tim S wrote:

Failing that, a ventilated ridgewould probably cost far less than
vent tiles (although 64 sounds like rather alot - one per rafter space
ought to be adequate).

That is one per rafter space. I must get some pictures of the roof on the
web - needs to be seen to be believed! The problem with the ridge vent idea
is that I don't have any sort of apex under the ridge - dormer roofs are
flat and cut straight in like this:

ASCII Art mode

Side profile:


==========^===========
| / \ |
| / \ |
| / \ |
| / \ |
/ \
/ \
---------------------------

Do you see the problem?

Indeed...

Could you get away with raising the ridge tile half an inch? i.e. lift
of the capping tiles, insert suitable angled vents - something like a L
shaped weep vent would do - and then bed the ridge tiles back on?

Failing that, people like Ashphaltic to a dry ridge system that you can
use for fixing ridges without the need for bedding in mortar, I have a
feeling they have one that includes a vent as well.

--
Cheers,

John.

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