Fiberglass wall insulation in timber frame house

kilclon

A friend of mine is looking to finish his house which was built to shell stage around 15 years ago. The wall build up is pvc cladding, weather membrane, osb, 150mm stud. Building is in good condition considering it hasn't been lived in etc. They have a bunch of fiberglass insulation bats similar to http://www.boards.ie/vbulletin/showthread.php?t=2055036302which they originally intended to use. R-value of 19 I believe.

Is it advisable to use these considering they effectively have a clean slate to work from? If not, what build up would be advisable? The house is large so taking up room space is not an issue.

Cheers.

BryanF

kilclon wrote: »

A friend of mine is looking to finish his house

1. which was built to shell stage around 15 years ago.
2. The wall build up is pvc cladding, weather membrane, osb, 150mm stud.
3. Is it advisable to use these considering they effectively have a clean slate to work from?
4. If not, what build up would be advisable? The house is large so taking up room space is not an issue.

Cheers.

1. what part of the country is the house? id be cautious and check every inch for damp/ rot, especially at the boots & hat while you have the chance the see into the wall structure.
2. as a minimum I assume the following: pvc cladding has a decent rainscreen cavity space outside the weather membrane. install the mineral wool filling the 150mm stud frame completely, then install a fully taped and sealed vapour barrier/airtightness membrane to the inside followed by plasterboard. you may want to consider a service cavity inside the air-tightness membrane, of max 70mm which would house electrics etc, and will help avoid puncturing the AT membrane. this could be filled to give further insulation
3. free insulation -i dont see why not. though you'd be surprised how much insulation you'll install into a house, so my advice would be to use the old stuff up in the attic to depth of at least 400mm
4. maybe cellulose

you really need to employ a thrid party professional: arch/eng/surveyor to consider the overall insulation, air-tightness, ventilation & heating strategy - these should be considered together!

kilclon

BryanF wrote: »

1. what part of the country is the house? id be cautious and check every inch for damp/ rot, especially at the boots & hat while you have the chance the see into the wall structure.
2. as a minimum I assume the following: pvc cladding has a decent rainscreen cavity space outside the weather membrane. install the mineral wool filling the 150mm stud frame completely, then install a fully taped and sealed vapour barrier/airtightness membrane to the inside followed by plasterboard. you may want to consider a service cavity inside the air-tightness membrane, of max 70mm which would house electrics etc, and will help avoid puncturing the AT membrane. this could be filled to give further insulation
3. free insulation -i dont see why not. though you'd be surprised how much insulation you'll install into a house, so my advice would be to use the old stuff up in the attic to depth of at least 400mm
4. maybe cellulose

you really need to employ a thrid party professional: arch/eng/surveyor to consider the overall insulation, air-tightness, ventilation & heating strategy - these should be considered together!

Thank you Brian, helpful as always.

1. The house is in Carlow. Everything will be thoroughly checked before any work has started.

2,3 + 4. I'll need to check the cavity behind the cladding. What would be adequate? The build up you describe is what I was thinking. Assuming he was to go with cellulose insulation in the walls as you suggest, what insulation would be used in the service cavity?

The timber frame of the house is raised off the ground on mass concrete walls creating a basement area below which as various ceiling heights due to the many split levels in the house. The basement will be used for storage/garage space. As well as using the fiberglass in the attic spaces could it be used in the ceiling of the attic for ground floor insulation? Would extra be required?

Many of the ceilings are vaulted. They have osb above the rafters. This product was intended to provide ventilation. Can the fiberglass also be used here? Extra insulation will surely be required? Will an insulated polyiso slab do?

To complicate matters further, only roughly one third of the house is being finished for now (very large house). This will have a few implications. Three that immediately spring to mind are having ventilation and heating systems capable of being added to at a later date and insulating internal walls to external wall standard. Any others you can think of?

I realise that a professional will be required to properly spec this but for now he just wants to get a rough idea of material cost before proceeding. I will be able to do this for him if I have a good idea of a possible spec option.

Thanks again

BryanF

Enough said already - if your specifying away you go

kilclon

Turns out there is no cavity between the pvc and membrane. Have a more qualified Engineer organised to come and inspect. Will this cause major problems?

BryanF

Wait for eng and post back with pictures

kilclon

Will do, cheers Brian.