Live self-Builds - mod warning in post no. 1

Got the results of my air-tightness test on my new build today. 0.6ACH. Happy with that.
Block wall with 250mm pumped bead cavity. Sealing behind the electrical sockets made the big difference - 2.2 down to 0.6 after this was done.

What we did is chased the walls, use the pink bonding to parge the chase and back of the socket boxes and then pushed the box into the soft pink bonding mix.

Might have a photo or two at home later

0.54 ACH

I hope this helps

An REMEMBER - inside walls should be treated the same (blocks are porous)

We scud coated all walls - door reveals and the tops of the walls so that the block work was FULLY ENCASED in cement

This picture also shows the row of Quinn at floor level to reduce thermal bridge downwards

Also note the conduit went up to BELOW the membrane and then all cables etc run below the membrane (suspended ceiling). The only perforation through the membrane for cables (TV, Satalite, outside lights etc) was a single piece of ply in the center of the house with a hole for each cable which each of which was sealed with guke. Bunches of cables are hard to seal around,.

In cupboard through door way you can see service ducts coming up - we had to go back and tape more proficiently than first done the DPC to the ducts. Put lots of ducts in you can always cap them - gates, lights, CCTV, alarm, garage, well, garden sockets, floor lights, Xmas lights ........

Lastly I know sleep in passive comfort where this picture was taken (its the bedroom)

lownhard wrote: »

Why do the internal walls? Air coming up from the ground?

No - where you have it "T" with an external wall it will leak through the block work

just do it wrote: »

FC

What's it costing you annually to heat your house? I know you have the figures :D

Heating & Hotwater is of the order of 4000Kwh primary energy (electricity) for 350sqM - Hot water used around 65% of that number

The PV on the roof (I have no solar thermal panels) produces around 4000Kwh and I use the grid as a "battery" - so the system has zero "running" costs.

In reality the PV will pay for itself in around 7 years - (assuming the ESB Networks keeps paying me 9c per excess unit - they have stopped paying this for new connection) In any event we should never suffer #FulePoverty

Reason for PV vs Solar Thermal is that in the summer we export around 1800Kwh and Solar Thermal would be "dumping" that excess while still trying to give meaningful input to the shoulder of the year (March April / Sept-Oct)

Given there is no export payment would I do things differently today - may be - depending if building control would allow me to not explicitly meet the DEAP requirement of 10Kwh/sqM

Old Jim wrote: »

I was out of the country when it was done so don't have the full details but I believe it involved using a blue silicone-like sealant(Fortax 6400 by Gerband) and worked this into all the holes and edges of the metal backing box for all the electrical sockets. That adhesive is typically used for adhering airtight membranes to surfaces.
Obviously the easier method is to parge the chases with this or other suitable airtight 'goo' or the pink bonding mentioned earlier before the electrical first fix is done.

Well done on a great airtightness result - but more questions! What type of build? Single or two storey? Other elements of the airtightness strategy?

Building a 2 storey at the moment and finding I'm educating people regarding airtightness, including the supplier of the airtightness membrane!

Old Jim wrote: »

Thanks. It's a 2-storey, fairly standard design. The design gave it the best chance of good airtightness - no chimneys, no recessed lights in the airtight layer. We wrapped the hollowcore on all sides, taped all penetrations, windows and doors, filled any ducts/conduits going into the attic. Lots of things we didn't do including taping the wall to floor junction, separating wires going through airtight layer - all the wires went though in the one place bunched tightly together and taped around.
I wasn't expecting such a good result as we didn't focus massively on detailing.

Very interesting and good to hear. You'll have to stick up a few photos at some stage

Old Jim wrote: »

I was out of the country when it was done so don't have the full details but I believe it involved using a blue silicone-like sealant(Fortax 6400 by Gerband) and worked this into all the holes and edges of the metal backing box for all the electrical sockets. That adhesive is typically used for adhering airtight membranes to surfaces.
Obviously the easier method is to parge the chases with this or other suitable airtight 'goo' or the pink bonding mentioned earlier before the electrical first fix is done.

Would silicone or mastic do the same job as the product you used?

fclauson wrote: »

yes until it dries out and shrinks - there is a reason these products are more expensive !!

Wouldn't have known that. Thanks. What is the pink bonding that you parged the back of the chases with? Is it just standard gypsum hard wall?

Slow work!!

Villain wrote: »

It is, I remember it well but well worth it, try make sure tape isn't tight on the corners so when window boards are "beaten" into they place they won't puncture the tape.

I have learnt that already. There is a good chance the first window will get redone as I learn!

THE DON FANUCCI wrote: »

what did you fill your cavity with? and how did you close the cavity at the windows? that tape looks great job! painstaking i'd say. did you fit it? or can you hire somebody to do this?

Cavity to be fully filled. Cavity closed with PIR tightly wedged. Did the tape myself. You can hire someone but I would recommend the DIY route. It's not that tough.

893bet wrote: »

Electritions are flying! Really happy with how neat they are!

How do you intend to achieve air tightness behind sockets and chases?
U only get one chance at it.