preparing for HRV (airtightness)

PJMCKE

Hi,
I am preparing/specing my build for airtightness before tendering out for contract to builders. I really want a HRV system and airtightness is where I am falling down and how to spec accordingly. If anyone out there have a successful HRV and a airtight house using block construction as below, i would be greatful of their comments.

My issues lie around.

-) Hollowcore first floor. How do I get this as airtight as possible to prevent airflow between floor levels (around the innerleaf block where the hollowcore rests) and also in the hollow core itself as surefly and airflow in the cavity will migrate down the hollows of the core.
-) Is there a enveloping system for a block build internally. My house will be 100mm block 110 mm cavity and 100block (full cavity fill preferred). Insulated plasterboard on inner perimiter walls K17 Kingspan. How is it best to seal the plasterboard to the walls to prevent unwanted airflow and also to wrap the insulation to meet with the screed over the floor insulation and also to seal with insulated ceiling board.
-) best practice on using insulated plaster board at window openings. How is the cavity closer working here so as to encorporated the 50mm insulated plasterboard.
-) Lastly the roof levels and enveloping the first floor to minimise airflow back down from the roof area.
Alot of questions, so hopefully you can put my mind at rest .

Retro-Fit

Its all about attention to detail, an air tight spec is only effective if it is implimented and a few rules for trades are enforced. You will find that build difficult to heat with huge cold bridges. Insulated plasterboard is as useless as a snooze button on a smoke alarm for many reasons. Keep all your insulation close and continuous. One solution is 100 polyiso on 215 block inner leaf, wrapped around reveals and down to footings, make windtight then construct outer leaf.


I'd suggest you do a one day course with Siga or McCann and Byrne Ecological building systems for the airtightness. Hardwall plaster is the best airtightness membrane.

Quack13

Retro-Fit wrote: »

Its all about attention to detail, an air tight spec is only effective if it is implimented and a few rules for trades are enforced. You will find that build difficult to heat with huge cold bridges. Insulated plasterboard is as useless as a snooze button on a smoke alarm for many reasons. Keep all your insulation close and continuous. One solution is 100 polyiso on 215 block inner leaf, wrapped around reveals and down to footings, make windtight then construct outer leaf.


I'd suggest you do a one day course with Siga or McCann and Byrne Ecological building systems for the airtightness. Hardwall plaster is the best airtightness membrane.

This is an area that interests me too...although i am just starting to research it.
You say plasterboard is useless...what are the alternative..insulation foam?

I would be interested to hear from people with previous experience of setting up a house for HRV and what they learned from the experience.

Retro-Fit

Insulation foam isnt great, you need about 400mm for a proper U-Value. Air tightness needs to be designed in from the start, very difficult to find designers who understand this.

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/

You also need a foreman who understands airtightness.

When looking at building occupant comfort, you need to consider all elements as an interconnected system. Insulation, ventilation and moisture management needs to be carefully coordinated.

Pm me and i'm sure I can direct you to a site in progress. Using Vapour barrier behind the services barrier, or taped OSB. or a building made externally windtight with softboard.

Carlow52

Retro-Fit wrote: »

..... Insulated plasterboard is as useless as a snooze button on a smoke alarm for many reasons.....

Such as?

sas

Retro-Fit wrote: »

Insulation foam isnt great, you need about 400mm for a proper U-Value.

Pm me and i'm sure I can direct you to a site in progress. Using Vapour barrier behind the services barrier, or taped OSB. or a building made externally windtight with softboard.

What is meant by insulation foam here?

Softboard may be a good solution but it's ridiculously expensive.

PJMCKE

Retro-Fit wrote: »

Its all about attention to detail, an air tight spec is only effective if it is implimented and a few rules for trades are enforced. You will find that build difficult to heat with huge cold bridges. Insulated plasterboard is as useless as a snooze button on a smoke alarm for many reasons. Keep all your insulation close and continuous. One solution is 100 polyiso on 215 block inner leaf, wrapped around reveals and down to footings, make windtight then construct outer leaf.


I'd suggest you do a one day course with Siga or McCann and Byrne Ecological building systems for the airtightness. Hardwall plaster is the best airtightness membrane.

Retro fit. You will have to elaborate a little more. Are you saying that concrete build with hollowcore will be difficult to heat or the insulation to be used in the build.

Retro-Fit

1. no continuity of air barrier
2. difficult to get services penetrations and sockets airtight.
3. foil backed layer does not continue across butt joint.
4. Phenolic insulant, not breathable, vapor open. problems with toxic off gassing and asmatha, formaldahyde biggest culprit.
5. no continuity of insulation at jambs and reveals, suspended floors etc.
6. dab fixings create still air cavity, perfect for mould. 10litres of moisture released into indoor air per day, will condense on cold surface of block. mould will migrate back into interior in summer.
7. dont hang yer flat screen telly on a nail into composite.
8. high embodied energy.