Wall made up of the following specs, cavity wall insulation question

[alpenbowl]

Moved into a house that was built in 2000 in Scotland.

It had cavity wall insulation done by previous owner in 2012. Slightly paranoid about this so took out an external vent a saw that the external wall is made up of the following.

1)Render on outside,
2)100mm concrete block,
3)50mm cavity that is now filled will mineral wool
4)100mm concrete block
5)60mm cavity of which 50mm is filled with polystyrene insulation board.

I got the paper work out for the cavity wall insulation as its says cavity of 85mm to be filled noted during the survey! How did they come to this?

Also after reading all the horror stories will the CWI give me issues, house is in a very good condition

 

[KenGMac]

alpenbowl, good evening.

Several things, it would appear that you have a oddly insulated property, given its age?

First, the width of the Cavity wall insulation? it is a possibility that the installed was paid by the width of the wall being filled?? it is possible that say, up to 50.mm [the general standard was paid as "X" ] and anything above that was paid at "X+1" or X2 or x3 dependent on Cavity width in the external wall Just a supposition? The installer could "boost 2 his profit by shall I call it exaggerating the cavity width??

OK the external walls cavity fill is well known as being a problem, in general the problems manifest as damp patches on internal plaster, at times extreme under certain conditions?

What is Unusual in your property is the inclusion of an internal Insulated Plasterboard ??? wall

Can you tell if there is an air gap between the internal surface of the external wall and the Insulation on the internally constructed wall?

Did you see a layer of foil on [what I am assuming ] is insulated Plasterboard, OK I have made a load of "Assumptions"

Any further information would assist??

Where are we now? If, I STRESS IF, the fiber in the cavity of the external walls has failed and it is allowing rain water to bridge the cavity, and saturate the internal leaf and its applied Plaster, the internal plasterboard?? and its associated Insulation will.

1/. Mask any problems in the external walls?

2/ Assist in keeping the property fairly warm.

One final thing? did the Original owner work Off-Shore?

Ken.

 

[alpenbowl]

Hi KenGMac, I will try and answer above post best I can and uploaded a photo so you can see it even more clearly. Just to confirm the cavity wall insulation was done in 2012 and no visible issues of damp. I just know that in CWI can cause issues so was really asking what are the risks with CWI as you get a lot of conflicting opinions even on this forum.

Can you tell if there is an air gap between the internal surface of the external wall and the Insulation on the internally constructed wall?

These is a 60mm between inner surface of concrete block the back of the plaster board. This has been been filled by what I can work out by 50mm polystyrene sheeting so leaves 10mm gap.

Did you see a layer of foil on [what I am assuming ] is insulated Plasterboard, OK I have made a load of "Assumptions"

No I cannot see any foil as something like kingspan wall insulation would have. It seems that it is just a 50mm thick sheet of polystyrene between the studded wall.

One final thing? did the Original owner work Off-Shore?

Ha Ha, no but I do and moved away from Aberdeen a year ago.

Anyway here is a picture from the inside to out. Ignore the pink circle as this is to block the wall vent as not the warmest this time of year.

 

[^woody^]

There is nothing wrong with a 50mm filled cavity. There are horror stories about everything if you what to read them.

 

[KenGMac]

alpenbowl, evening again.

As Woody states there must me hundreds of thousands of properties that have this type of Cavity Fill, but?

I would ask a rhetorical question why would anyone spend money on Internal insulation on a Cavity Filled wall ? it seems like an odd thing to do unless there was something happening on the inner surface of the external walls?

Do all internal surfaces of external walls have this internal Insulation system in place? or is this system confined to certain areas of the property on say a North or West facing elevation.

If left unoccupied for even a short space of time when you return is there a damp musty smell in the Property.

One possibility? can you obtain a sample of the Cavity Fill? if so it may be possible to test and see if the fill is damp or even wet from within the vent area.

Ken.

 

[^woody^]

There is no actual problem. So why investigate anything, and why worry about anything?

 

[garyo]

The original parts of my last house were 50mm full full. Dating from the 40's with its masonary cavity closers and solid uninsulated concrete floors it was noticeably colder than the newer extended parts of the house.

No damp issues at all, but I may well have added 25mm of PIR to the inner walls if gas got any more expensive.