I'm going through the horrible, brain frying process of looking at kitchens for the new house.  Initially, I was thinking about limiting wall units to only the internal wall separating the utility from the kitchen area, but it seems that I'm going to end up with a slightly boring kitchen.  It would, I suspect, look better if I could have the units going around the corner towards the window, as well.

 

However, I'm spending a lot of money and effort on this passive type build, so I really don't want screws to be heading into those carefully constructed MBC walls.  I'll need to find a fix for this as the problem applies equally to plenty of other walls that I need to attach things to.

 

Does anyone have any suggestions?

Screws are 99.9% airtight when they are done up tight. I wouldn’t be worrying ..! 

 

Do you know the stud layout or do you have the OSB lining on your build ..?

You're OK, as there is a service void between the plasterboard internal finish and the vapour tight panel.  Best to try and fix heavy stuff to the battens (which run vertically on 400mm centres) if possible, but if not then use hollow wall anchors like these, like these: 

 

They are great, as the threaded part remains firmly in the wall when you remove the screw and cannot drop into the void like the spring loaded ones.  I've used loads of them on our MBC frame and found them to be foolproof.  Just make sure you only get the short ones for fixing to any outside wall, as the service void is only 45mm deep, and when putting them in you need to get the whole length into the wall before expanding the back out.  I used 37mm ones with M5 screws and they will take a heck of a load.

 

I bought the gun to pull these in, as it's cheap and a lot better than the method of using the screw shown in that video.  You can get all these and the gun from Screwfix: https://www.screwfix.com/c/screws-nails-fixings/hollow-wall-anchors/cat7280101?brand=rawlplug and: https://www.screwfix.com/p/rawlplug-heavy-duty-setting-tool/8499g

 

Brilliant, thanks chaps.  I will get on and see about a less boring kitchen layout.

If you think there is a particular issue at any point a blob of silicone in the screw hole or even smeared on the screw will seal it.

6 minutes ago, Ferdinand said:

If you think there is a particular issue at any point a blob of silicone in the screw hole or even smeared on the screw will seal it.

 

 

Unfortunately that won't work with the MBC system, as there is a 45mm deep void between the plasterboard and the vapour tight membrane and that service void is open to the ceiling void. 

 

To be safe, it's best to use a drill stop to make sure holes for hollow anchors aren't drilled too deep and hit the vapour tight board.  I use bits of scrap plastic pipe pushed over the drill bit up to the chuck, so there's only about 30mm of drill bit exposed, and that works OK.

3 minutes ago, JSHarris said:

Unfortunately that won't work with the MBC system, as there is a 45mm deep void between the plasterboard and the vapour tight membrane and that service void is open to the ceiling void. 

 

Are you sure?

 

I thought there had to be a fire stop?  I have a horizontal batten at the top of my service void, only drilled for pipes or cables.

Yes, I'm sure.  I have pipes and cables running through the ceiling void and dropping down into the wall service void all over the place, with no battens in the way.  It's handy, as I've retrospectively run some ethernet and speaker cables down the wall service void from the eaves space..

stop would be on the outside surely.

I used special plasterboard throughout the house as coming from a house with solid walls I was used to putting things where I wanted without worrying about special fixings, battens and noggins etc.

 

Expensive board but as well as the extra strength you get good acoustic value too.  My floor to ceiling kitchen cabinets and wall cabinets are all fixed straight into the plasterboard. 

 

I’m glad I spent the extra was worth it to me. http://www.roomsmadeforyou.british-gypsum.com/solutions/gyproc-habito.aspx