Insulation and ceiling options for verandah

Bells67

Hi there, loving this workshop forum! 

Like others, I've been reading through a bunch of posts to see if there were already answers to my questions but couldn't find anything that covered the lot so I've started this new post. Hope that is okay!  We are 5 years into a 1-year renovation plan and one component has been replacing joists, deck boards and handrails on our verandah and adding insulation and a ceiling to stop condensation (which is prolific) and make it cooler in summer.  We are not quite done with the decking, but getting close.  Because we have painted posts, beams and rafters which will require re-painting, we need to decide on the insulation and ceiling options to use so we know which beams/rafters will remain visible.    

We have a three-sided wrap round deck with bullnose roofing (each side is 4m long and it's 17m long on the front). From exterior house wall to outside deck facia beam, it's around 2.0m long.  There is absolutely nothing consistent about the spacing between the rafters - or anything else about our house for that matter - so sadly, it's not a matter of simply buying 900mm wide insulation panels and slipping them in between each. Spaces between rafters range from 780 to 880 (I think, haven't measured them all). Power runs along one of the rafters and is then channeled on top of the facia beam (under the roof) to 3 or 4 flood lights that are also attached to same along the length. The corners, where the hip rafter is, might make installing insulation and a ceiling complicated?  Photos are attached. I was thinking that the simplest ceiling option is installing insulation close under the roofing somehow, then slipping the ceiling panels in above the facia beam (where it would sit above) and screwing the panel into the bottom of the battens. This would leave most of the rafters exposed, but not the battens.  

My questions:

- Is there a good insulation option (like foil board or Aircell or some other product that is waterproof) that can be easily cut to size and installed directly under the colourbond within each rafter space? 

- If so, how would we attach it if we are not removing the bullnose to sit it on top of the rafters? Can it sit on the ceiling panels, or does it have to be close under the bullnose? We get heavy condensation, so it needs to be rot/water/mould proof or effective enough to stop the condensation.

- What would be most cost effective, easy to fit, mould-resistent ceiling panel options?  Hardie-board?

- Is it okay to fit them into the rafter spaces as I've noted above, or should we simply install ceiling panels in large sheets on the lowest points (bottom of rafters) with all the joins running paralell with the deckboards? 

If you think this belongs on a different 'board' or I need to seek help elsewhere, it's totally okay to let me know. I have some other questions relating to installation of french doors where our bay windows used to be and I'll place that on the 'Whole of House' board.

Thanks, MichelleCorner with hip rafterAlong front length of deckpower and lights to work aroundAnother along the front

Jewelleryrescue

Hi @Bells67 

Your very welcome to ask question here any time.

Well I note your condensation issues. 

Ps I love your  bull nose verandah and new deck.

Insulation

I am not sure how  you will benefit  from any insulation you add there ?

Your thinking  insulation so you might be getting high radiant heat from the tin during the day.?

If you can confirm that  possible assumption?

Any how lets  talk insulation and your bull nose roof shape  for now just talking out loud to get your  thoughts back.

Foil roof sheeting can  be heat reflective to help reduce the heat of the metal roof getting through.  Another type has foam inner core that adds more heat blocking properties x3 $. I am thinking it can be glued to your metal bull nose and follow its shape but I might recommend unscrewing middle rafter screws to allow a single sheet to run above that rafter.  Option 2 You  may wish to run to that middle  rafter along the  under roof  line and encapsulate the middle rafter from below (down one side across the bottom and up the other side  back to roof line.)  So no roofing  needs undoing. 

I would start the sheet  near the house and attach  on the underside of that first rafter then over the top of the middle rafter (or encapsulate it)  then spot glue to the bullnose curve with the insulation at the end bending back reversing on itself pointing inwards at the house and it is stapled on top of that beam  for easy attachment and  access.

I think this would look the neatest  and provide best coverage for inside the bull nose

Foil boards or foam non foil versions  for NZ  may be hard to fit in bullnose shape you may end up with flat angle between middle rafter and outer beam.  Not as visually appealing as  bull nose.

Well your Idea to add a villaboard (hardiboard) under the roof rafters  will work you can use any insulation above it including batts. you will have to add some more timber to support sheeting.  Insulate as you go.  This  works well as the big air gap above will help clear   condensation. Where as  foil sheeting will not have a much air gap if at all . It wont hurt insulation but continuous  mositure can lead to issues it should drip near outer roof beam if it does

All the  insulation is water proof and has  fire /ember resistance  Batts will hold water and  can go moldy if  continuously  allowed to get wet  redripping condensation ?  (not in  your case though.)

The  electricals should be  below potential insulation points so is  ok

Yes that corner is  always a  joy to do just need to add timber  above  optimal sheeting joins. 

Dosnt matter  which  board you post  on they are all seen in this common board area,  🙂

Well  lets talk and others  can join in too.