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DIY Air Tightness Test


richo106

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Hi All

 

All being well my shell will be complete in the next 8-10 weeks with all windows, doors, roofs etc installed

 

I am having a cold roof space

 

When would be a good time/at what stage to do a first DIY air test?

 

All my windows/doors will be taped from frame to blockwork

 

I have had traditional joists sat on the inner block, these have been sealed round with the mortar but aware of shrinkage etc.. what is the best way to combat this? Air tight paint sealing all edges?

 

My floor make up will be slab, 200mm PIR and then 50mm screed....is this best to air tight paint the perimeter junction?

 

What is the best foam to use to seal cables, pipes and waste pipes going through the brick and block? I was thinking about taping pipes also

 

My biggest concern is the first floor ceiling, i will have many spot lights and MVHR ducts travelling through it, I am happy to tape all ducts. Do I need a membrane stapling to joists before plasterboarding?

 

Any advice on any issues raised much appreciated

 

Many Thanks

 

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As you are still in construction phase, is it too late to change it for a warm roof?  That puts all the insulation and air tightness at roof level and makes all the internal work, ducts, lights so much easier, and you get a nice warm loft space as well.

 

That is right up there at the top of the "I am glad I did that" list.

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Strictly speaking mine is referred to as hybrid.  It has 100mm of wood fibre board over the rafters and then 200mm full fill insulation between the rafters.

 

It means the entire loft space is inside the insulated air tight envelope so you don't have to worry about insulating mvhr ducts etc or ceiling penetrations.

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25 minutes ago, ProDave said:

Strictly speaking mine is referred to as hybrid.  It has 100mm of wood fibre board over the rafters and then 200mm full fill insulation between the rafters.

 

It means the entire loft space is inside the insulated air tight envelope so you don't have to worry about insulating mvhr ducts etc or ceiling penetrations.

Does sound good but expensive haha. With an ridiculously stretched budget that might be a stretch too far but that would be ideal

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I'm doing a retrofit. We have a 150 year old roof which I don't plan on ripping up any time soon. I plan on laying Intello membrane across the underside of the roof joists, taping to the insulation/wall airtightness detail, then studding off a service void for lighting cables etc as to not penetrate into the cold loft, the only penetration we will have is for the MVHR valve coming into each room, which can be appropriately detailed. Standard insulation rolls will be applied between and over the joists in the loft, which will overlap with the wall insulation around the perimeter (whilst ensuring the eaves aren't blocked to allow for sufficient ventilation)

 

Not perfect, but a damn sight better than what we currently have and short of replacing the roof, probably the best we can do. 

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On 16/02/2023 at 16:26, Dave Jones said:

put a fan (normal desktop 12" will do) in a doorway/window and seal around it to the frame with bin bags to depressurize the house then go draught hunting.


did you actually do this ?

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@IanMcP from my reading around here there is quite folks making their own home made blower test kit.

I want to rig up one soon - bookmarked this thread that has some details

Edit - what @Jenkisaid above min before me. 😁

Edited by Gill
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