air tightness issue

[JackofAll]

So I failed to have a board in place with holes drilled to accommodate cables above membrane, spark punched a few holes big enough to run several cables through and ran in same. I've tried taping but due to spacing between cables cannot get a satisfactory seal. would low modulus silicone do or soudal airtight foam for windows/doors?

[Redbeard]

Oh  dear! You are not alone, though. Ideally the spark would have used purpose-made cable grommets. Would you have room to separate the cables and cut a square out of the membrane? Get a piece of EPDM (rubber roofing) bigger all round than the square you have cut out and drill holes a good distance apart for the number of cables you have, each hole slightly undersized for the cable. Then make a cut from each hole to the edges of the EPDM square and tuck the cables in. Then get short lengths of air-tightness tape and tape round each cable to the membrane. Finally, use air-tightness tape to tape the EPDM square into the hole in the membrane.

[ProDave]

The design flaw is why to so many cables need to penetrate the air tight layer?

[Kelvin]

The airtightness layer is on the exterior bits of the house so where are all these cables going? Post up a picture of the area and then further out so we can see it in context. 

Edited March 13 by Kelvin

[JackofAll]

will post pics tomorrow when onsite, just after seeing an airtight gromit for multiple cables, but on the pricey side though pretty much like what you were suggesting redbeard. kaflex I think its called.

[Redbeard]

You can make your own. I would not like to guarantee they would be quite as good as the proprietary ones, but I have had some success. Basically EPDM, as many holes as you need, and air-tightness tape around the perimeter.

[WisteriaMews]

3 hours ago, ProDave said:

The design flaw is why to so many cables need to penetrate the air tight layer?

I'm not quite at the stage yet to plan the cables on my self build, but puncturing the airtight membrane is something I've half started to think about.

 

Do you have any tips on how to avoid them? As I said I've not given it serious thought, but mains electric, connection from the solar panels and TV aerial needs to come in. Power for the outside sockets, lights, security cameras and alarm need to go back out. It's adding up to a worrying list.

[crispy_wafer]

7 minutes ago, Redbeard said:

You can make your own. I would not like to guarantee they would be quite as good as the proprietary ones, but I have had some success. Basically EPDM, as many holes as you need, and air-tightness tape around the perimeter.

 

indeed, I bought a pack of 10 of them, and to be honest, if you can buy a sheet of EPDM, cut it into sections and use a drill bit to puncture a hole in it you'll be 99% of the way there.

[Kelvin]

34 minutes ago, WisteriaMews said:

I'm not quite at the stage yet to plan the cables on my self build, but puncturing the airtight membrane is something I've half started to think about.

 

Do you have any tips on how to avoid them? As I said I've not given it serious thought, but mains electric, connection from the solar panels and TV aerial needs to come in. Power for the outside sockets, lights, security cameras and alarm need to go back out. It's adding up to a worrying list.

The best strategy is to try and design the penetrations out as far as possible. I ducted as much as I could under the slab into the plant room so all my electrical/data cables and water into the building is through ducts. I included a couple of extra ducts to both ends of the house to make adding something else easy although I was mostly using up some leftover ducting. 
 

Where I had to come through a wall I also used ducting suitable for the size of the cable then sealed up both ends with Pro Clima Roflex duct seals and tape. I used an intumescent foam to seal the ducts. Pro Clima also do a butyl seal tape that I found to be a great product for harder areas as you can form it to shape. I also sealed all the ducts using Filoseal. 

 

https://insulationmerchant.com/collections/pro-clima

 

https://www.filoform.co.uk/filoseal-re-enterable-duct-sealing-system

Edited March 13 by Kelvin

[PNAmble]

31 minutes ago, WisteriaMews said:

Do you have any tips on how to avoid them? As I said I've not given it serious thought, but mains electric, connection from the solar panels and TV aerial needs to come in. Power for the outside sockets, lights, security cameras and alarm need to go back out. It's adding up to a worrying list.

we created all the penetrations from the plant room before the first air test.  A 100mm duct for power (in and out plus PV) and 50mm duct for data/control wires (BT fibre in, CAT6 out (plus spare), ASHP control).   These go into an external kiosk.  Which has an external distribution board and a POE network switch.  What this means is that all external wiring and external data requirements are wired with no additional penetrations plus if we forget any we can add them at a later date. 

 

Air tight grommets used to seal ducts. And they will be filled with air tight foam once second fix is complete.  They were temp sealed for our first air test (0.42 ACH) 

Edited March 13 by PNAmble

[Alan Ambrose]

Can I ask? Were the DNO & Openreach happy with one joint kiosk for a combination of power & data?

[JackofAll]

To be honest I never thought through the wiring routes so buck stops with me at the end of the day. This morning I had a good look round and there were many accidental holes that need to be addressed. Place is like a golf course, Disappointed is an understatement. Just another job added to the ever increasing list.

[JackofAll]

[JackofAll]

[JackofAll]

[JackofAll]

[JackofAll]

[JackofAll]

[PNAmble]

1 hour ago, Alan Ambrose said:

Can I ask? Were the DNO & Openreach happy with one joint kiosk for a combination of power & data?

 

The Kiosk won't hold the meter that Kiosk is about 30 meters away at the front of the property,  the mains is then ducted into the second kiosk and direct through the "power penetration" to the main distribution board in the plant room.  

 

The second kiosk is a smaller distribution board feeding the EV, External Sockets and Lights fed by a high amp cable.  with also a plug socket to power by POE Switch.

 

I've run through the plans with OpenReach and they are comfortable although they treat it as a "High Risk" Installation which requires someone with special training.  They did say that this is becoming more common due to properties trying to get airtightness and limiting penetrations.    OpenReach's ONT will be in the Plant Room but the OpenReach termination point is in this second kiosk (we've pre fed the OpenReach cable through the Data Penetration).  Interestingly OpenReach refuse to install the ONT in the external kiosk and allow me to just connect by CAT6 - no idea why.  

[Mr Blobby]

This is heartbreaking to see.  You could use these photographs to compile a guide on how not to install cables.

 

Our spark starts on site tommorrow.  I plan to be there every day to prevent this sort of butchery.

 

I think the only thing to do here is cut back the battens around the holes and then patch with some membrane and install a grommet.  The problem is the grommet will need to be fed over the end of the cable and that is probably all the way back at the consumer unit now.

Edited March 14 by Mr Blobby

[Iceverge]

That's a nightmare.  Sorry to see it. 

 

However not terminal. Nothing ever is. 

 

If you're in Cork you can borrow my DIY blower door fan and if you put 2 days in with it and plenty of this you may still get a result. 

 

(f)air tightness® OR sealant for air tightness, 600ml tubular sausage bag (prodomo.ie)

 

 

It'll require the house to be empty of other trades and plenty of patience though as lots of those holes won't seal on first attempt. 

 

Wear gloves as it has the texture of sticky chewing gum. 

 

 

[Iceverge]

14 hours ago, WisteriaMews said:

I'm not quite at the stage yet to plan the cables on my self build, but puncturing the airtight membrane is something I've half started to think about.

 

Do you have any tips on how to avoid them? As I said I've not given it serious thought, but mains electric, connection from the solar panels and TV aerial needs to come in. Power for the outside sockets, lights, security cameras and alarm need to go back out. It's adding up to a worrying list.

 

 

Plan for ZERO holes in the membrane.

 

I did this by. 

 

1.  Running a service cavity below the membrane, making everything go in here. 

 

2. Put plywood where ever you need to penetrate and tape the membrane to that.  Use the ONE WIRE for ONE HOLE mantra. I even drilled the holes and labelled them for the electrician. 

 

3. That left a very simple set of instructions for the electrician.

• Don't ever make a hole in the membrane, only in the ply. 
• ONE WIRE per ONE HOLE
• If there's any accidental holes just tell me. There will be no bollockings, no scolding, no problem. Just tell me and I'll fix it.  

 

[Iceverge]

Here's how I did the top of the conduits as membrane is almost impossible to seal into  the corner.  Continue the chase up through the wall plate. Screw a square of OSB down from the top and seal with airtight paint.  

 

 

Then run the membrane down the wall under the square of OSB. Seal to the wall everywhere with airtight sealant.  

 

 

Cut back the membrane as shown and seal to the OSB with airtight tape. 

 

 

That leave the electrician plenty of space to take the conduit above the level of the plasterboard and bend the wires into the service cavity without any need to go near the membrane. 

 

 

 

 

[Redbeard]

23 minutes ago, Iceverge said:

That's a nightmare.  Sorry to see it. 

 

However not terminal. Nothing ever is. 

 

 

My thoughts entirely. 

 

9 minutes ago, Iceverge said:

ONE WIRE per ONE HOLE

 

I am assuming the wiring is pretty well done and that it is far too late to disconnect cables and run them thro' grommets as should have been done. Therefore, as per @Iceverge's mantra above, separate out those bunches, get some OSB/ply behind if you can (as it's a darn sight easier to stick to something which doesn't move away from you!) and do the 'split grommet'/tape idea which I described above. *for each separate cable*.

14 hours ago, Kelvin said:

Pro Clima also do a butyl seal tape that I found to be a great product for harder areas as you can form it to shape.

I have never used Pro Clima's butyl but still have some Pavatex butyl tape I use when necessary. It takes bends better than standard a/t tape, though Tescon ('cloth') tape is pretty forgiving.

 

It is very tedious but do not despair. By the time you have 50% of those holes done it will feel like it's all downhill (in a positive way!) from there.

 

And +1 to the DIY 'blower door' idea. That's on my list of things to make too.

 

Best of luck.

[Iceverge]

 

Here's how I did the wires into the attic. The pic is taken looking down from above. A scrap trapezoidal piece of ply screwed to the trusses from below. The membrane cut back and tapes to the ply.  It doesn't need to be pretty but it needs to be neat and effective. 

 

ONE WIRE for ONE HOLE. 

 

No expensive grommets needed, just a squirt of airtight sealant from both sides. The sausage gun can be seen. Note there's plenty of space between the holes.