Stud wall in roof

[sadsjon]

I have a typical 200 year old 45 degree kent peg roof. I am fitting a
loft room, essentially insulating and plasterboarding the entire
triangular cross section (not bothering with knee walls) and a very
small ceiling. I want to keep it as a toblerone shaped room.

Half way down I have to build a stud wall to enclose an en suite
bathroom.

My question is, do I fit my 4x2 frame up and under the rafters to help
support or do I put my 4x2 frame alongside the rafters and fix my wall
to the rafters from the side.

Is there a preferred method? I'd like it to be strong and last and I
am a little worried that a roof that will flex with temperature and
winds will crack my paster, particularly at the corners where roof
plane meets stud wall for example.

jON

 

[The Natural Philosopher]

I have a typical 200 year old 45 degree kent peg roof. I am fitting a
loft room, essentially insulating and plasterboarding the entire
triangular cross section (not bothering with knee walls) and a very
small ceiling. I want to keep it as a toblerone shaped room.

Half way down I have to build a stud wall to enclose an en suite
bathroom.

My question is, do I fit my 4x2 frame up and under the rafters to help
support or do I put my 4x2 frame alongside the rafters and fix my wall
to the rafters from the side.

Is there a preferred method? I'd like it to be strong and last and I
am a little worried that a roof that will flex with temperature and
winds will crack my paster, particularly at the corners where roof
plane meets stud wall for example.

jON

There is no harm in using extra new structure to beef up the old.
Attach it all to the rafters..I HOPE you have arranged ventilation and
insulation..

Your stud wall ls should end up stiffening the rafters and ceiling
joists substantially.

 

[sadsjon]

But what is best? To fix the wall under the rafters or alonside the
rafters and screwing the new wall to the rafters from the side as it
were.

My inside ceiling beams are 4x2 and because of the problems getting
them level by chamfering the ends to 45 degrees and screwing it up
from underneath, I screw then to the sides of the rafters across the
span. This way I can get perfectly level.

Would this method be good and strong .. ?

I suspect that under the rafters is stronger and of course I don't
have to worry about getting horizontal timbers particularly level when
they are going to be inside the wall when its finished.

Either way I will fix to all the rafters that I can ... but under or
alongside???

cheers,

jON

 

[The Natural Philosopher]

But what is best? To fix the wall under the rafters or alonside the
rafters and screwing the new wall to the rafters from the side as it
were.

My inside ceiling beams are 4x2 and because of the problems getting
them level by chamfering the ends to 45 degrees and screwing it up
from underneath, I screw then to the sides of the rafters across the
span. This way I can get perfectly level.

Would this method be good and strong .. ?

I suspect that under the rafters is stronger and of course I don't
have to worry about getting horizontal timbers particularly level when
they are going to be inside the wall when its finished.

Either way I will fix to all the rafters that I can ... but under or
alongside???

Oh. I see.

Structurally it probably doesn't matter. I suspect that nailing to te
sides is better from that point view..

But I am concerned about the fact that you really haven't put any
insulation between the rafters before the wall gets built....that will
be easier to install if the wall doesn't obstruct the spaces between them.

 

[sadsjon]

I have 75mm Kingspan that I am fitting between and 50mm over the
rafters. (building regs - I think it gives me a .2u insulation)

That is the current job in hand.

I need to complete structural work before I fit the insualtion in the
area where the rafters meet the new stud wall, as you say it would be
easier.

If I screw my stud wall to the side of one rafter then I can still get
insulation in but its a bit fiddly.

If I screw my stud wall to the side of the rafters then I need to
screw thru the rafter into the stud wall (rafters 2 inch think, stud
wall 4 inch thick) which is why I thought that perhaps screwing the
stud wall -under- would be better as I would be screwing through the 2
inch stud wall timbers into rafter.

I also think -under- would be stronger.

As I have a clean sheet to work with I'd prefer to use the best
method.

jON

 

[The Natural Philosopher]

I have 75mm Kingspan that I am fitting between and 50mm over the
rafters. (building regs - I think it gives me a .2u insulation)

That is the current job in hand.

I need to complete structural work before I fit the insualtion in the
area where the rafters meet the new stud wall, as you say it would be
easier.

If I screw my stud wall to the side of one rafter then I can still get
insulation in but its a bit fiddly.

If I screw my stud wall to the side of the rafters then I need to
screw thru the rafter into the stud wall (rafters 2 inch think, stud
wall 4 inch thick) which is why I thought that perhaps screwing the
stud wall -under- would be better as I would be screwing through the 2
inch stud wall timbers into rafter.

I also think -under- would be stronger.

As I have a clean sheet to work with I'd prefer to use the best
method.

jON

Sounds like under is easier..try making the stud wall up as a unit,
jamming it under and then screwing upwards. Also you can get fish plates
that will sit either side of both bits if screwing upwards gets a pain.