airtightness in a bungalow

declan52

I am able to find loads of information on how to achieve airtightness with regards to warm roof construction in my build but what about the ceiling on the ground floor. Is it worth using a 500 gauge polythene on the ceilings and tape this to any wall. Or do you let this heat escape to the first floor were it is sealed in by tape and vapour control membrane. The house will have mhrv and triple glazed windows as well as being well insulated. I know about sealing cable conduits and ceiling roses on the ground floor but what about the ceiling were it will crack as the house drys out.

BryanF

show us a detail?

you seal the ground floor wall, around the ceiling/first floor to the first floor wall, if you do that completely your doing well

your air-tightness design should not be affected by the plaster drying out?

declan52

So tape around the edge of the ceiling and rely on wet plaster for airtightness on the ceiling. Forgot to mention about the join on the finished floor. All the details I intend to use are what the actual tape manufacturers specify.

BryanF

declan52 wrote: »

So tape around the edge of the ceiling and rely on wet plaster for airtightness on the ceiling. Forgot to mention about the join on the finished floor. All the details I intend to use are what the actual tape manufacturers specify.

create and air-tight layer from ground floor wall to first floor wall. the ceiling between ground & first floor is sort of irrelevant.its about the external wall air-tightness

have you got timber joists or PC slabs at first floor level ?

edit

declan52

It has attic truss

BryanF

Declan put up a section and zoomed in detail of the ground to first floor junction and separately first floor to attic junction.

MicktheMan

declan52 wrote: »

I am able to find loads of information on how to achieve airtightness with regards to warm roof construction in my build but what about the ceiling on the ground floor.QUOTE]


Its a bungalow, right?

declan52

I put a link up to a site showing a detail of what I hope to achieve but must have been not allowed. It is a bungalow but I have used attic truss so upstairs is useable for bedrooms.

BryanF

declan52 wrote: »

Is it worth using a 500 gauge polythene on the ceilings and tape this to any wall.

yes your heated envelope needs to be completely seal from an air-tightness perspective

you need detailed drawings prepared by your architect/arch tech.

BryanF

declan52 wrote: »

I put a link up to a site showing a detail of what I hope to achieve but must have been not allowed. It is a bungalow but I have used attic truss so upstairs is useable for bedrooms.

the link you posted is form a uk website, claiming compliance with regulations. it does not comply with building Regs in Ireland.

I recommend you get

• 1:10 details of all major external fabric junctions for YOUR build
• a detailed scope of work/specification that calls out your air-tightness strategy, materials and standard of air-tightness required to be achieved

(if you wish to discuss removal of any link please PM the mods)

declan52

BryanF wrote: »

the link you posted is form a uk website, claiming compliance with regulations. it does not comply with building Regs in Ireland.

I recommend you get

• 1:10 details of all major external fabric junctions for YOUR build
• a detailed scope of work/specification that calls out your air-tightness strategy, materials and standard of air-tightness required to be achieved

(if you wish to discuss removal of any link please PM the mods)

my plans were done in 2007 so airtight details weren't looked upon as important as it is today and I am not giving the architect anymore money for new drawings as he has had his pound of flesh from me already.
The link to the UK website was the best I could find online and I had included extra details more specific to my build.

BryanF

I wish you the best of luck on your project.

galwaytt

declan52 wrote: »

I am able to find loads of information on how to achieve airtightness with regards to warm roof construction in my build but what about the ceiling on the ground floor. Is it worth using a 500 gauge polythene on the ceilings and tape this to any wall. Or do you let this heat escape to the first floor were it is sealed in by tape and vapour control membrane. The house will have mhrv and triple glazed windows as well as being well insulated. I know about sealing cable conduits and ceiling roses on the ground floor but what about the ceiling were it will crack as the house drys out.

I have attic trusses in my old house, not currently using that floor - it's still attic via a Stira.

So, that portion of the truss, outside the framed 'room' in it, is effectively always only going to be part of the cold attic space (it will become your crawl space if you convert the attic).

So, to be effective I think the answer is 'yes' you do need to airtight the habitable space to ceiling underneath, for now. If/when you expand upwards you only have to deal with cutting the membrane and making good with new airtightness detail to the room above, then.

I don't see how you would remedially seal that easily, so do it now.

Me, I'd use something better than polythene - one of the proprietary membranes, suitably taped, would be my guess.

See attached as a quick sketch.

Cyan line is the airtightness layer you need for now.
Magenta line is the airtightness layer you will need if you expand into the attic eventually.
Red cloud area is airtightness area that is required irrespective, at ceiling line.

hope that helps

declan52

Yes thank you very much will have a look then for a membrane rather than polythene. Your sketch is the way I had thought of doing it.

galwaytt

declan52 wrote: »

Yes thank you very much will have a look then for a membrane rather than polythene. Your sketch is the way I had thought of doing it.

Just work out how you'll airtight the depth of the bottom chord, before you start closing things up - you won't want to have to come back to it later.