roof ventilation problem

steifanc

hi ,
today i came to find the roof of my new house completely latted and felted with roof TX ultra .
the problem is Ive a lot of pitched ceilings and had planned for a warm roof construction .
has any one any solutions to ventilation the roof with out taking the battons off and counter battening ?
i was half kinda thinking of blowing cellouse into the pitched roof so to leave a 50mm gap on the inside will be a pain in the ass
thanks!

sinnerboy

Option 1.
Intsall counter battens and counter - counter battens ( 3 layers of battens total)
Option 2
Use board insulation between rafters leaving 50mm vent space between top of boards and underside of felt .

You say

Ive a lot of pitched ceilings and had planned for a warm roof construction .

How are your plans being communicated to site , by that I mean what
a ) documentation and b) site management person(s) are in place ?

sas

sinnerboy wrote: »

Option 1.
Intsall counter battens and counter - counter battens ( 3 layers of battens total)

Why the 3 sb, is it to prevent cellulose pumping pushing the membrane
agaiinst the underside of the slates?

steifanc

sinnerboy wrote: »

Option 1.
Intsall counter battens and counter - counter battens ( 3 layers of battens total)
Option 2
Use board insulation between rafters leaving 50mm vent space between top of boards and underside of felt .

You say

How are your plans being communicated to site , by that I mean what
a ) documentation and b) site management person(s) are in place ?

A board seems to be the less expensive option , my taught were cellouse would give a better airtightness , ultimately it was down to me to deside , the kit went up in a day , unexpectedly fast on my end .

sinnerboy

sas wrote: »

Why the 3 sb, is it to prevent cellulose pumping pushing the membrane
agaiinst the underside of the slates?

The first layer of battens is in place already. To simply place battens directly over battens would not achieve a ventilation path each doubled up batten blocking up the space between the membrane and tiles.

So - existing battens - layer 1
Then battens over in line with rafters - layer 2
Then battens in line with layer 1 battens - layer 3.

steifanc

sinnerboy wrote: »

The first layer of battens is in place already. To simply place battens directly over battens would not achieve a ventilation path each doubled up batten blocking up the space between the membrane and tiles.

So - existing battens - layer 1
Then battens over in line with rafters - layer 2
Then battens in line with layer 1 battens - layer 3.

i here ya sinnerboy , pain in the ass tho , I'm wondering if i should make an issue out of it , alto it was never mentioned in the spec , i taught it would of been pretty standard with pitched roofs . even if i was going for a cold roof construction , the membrane is pulled tight not achieving a 25mm gap between the batton and the membrane ,
am i being too fussy ??

steifanc

sas wrote: »

Why the 3 sb, is it to prevent cellulose pumping pushing the membrane
against the underside of the slates?

no , if the insulation is against a suitable !! breather membrane there needs to be a suitable air flow on the cold side of the roof to dry any moisture that might appear , note that all roofing membranes are not suitable for this .

sinnerboy

steifanc wrote: »

the membrane is pulled tight not achieving a 25mm gap between the batton and the membrane ,
am i being too fussy ??

The battens will rot if the felt does not sag between rafters to allow water to drain under the battens.

You have no option but to strip the roof.

steifanc

sinnerboy wrote: »

The battens will rot if the felt does not sag between rafters to allow water to drain under the battens.

You have no option but to strip the roof.

thanks sinnerboy , should make for an intresting phone call tues !