Damp patch 5 feet up wall ( not drying ), older building with mineral wool type Cavity Wall Insulation installed in receny years.

Hi folks,

My recently deceased mother in laws house is in the process of 'being looked at by me' and due renovation.

A few years ago she had a grant for cavity wall insulation ( CWI ) and it was installed ( 82 yo and disabled ).

The installation used a blown in mineral wool type of insulation.

The property is about 100 years old.

On the front wall about 5 feet above ground level there is internally a damp patch prevoiusly not identified - behind furnishings - and it's not drying out. There are a few other damp patches here and there above the 1 metre damp proof course fault boundary. Possibly external mortar pointing also.

External mortar pointing/gutter downpipe leak in that area of the wall was found to be substandard and is now fixed - but it's still not drying out after 3-4 weeks.

What is the possibilty that the mineral wool insulation has become sodden in the area and - given the lack of ventilation in the cavity due to CWI - will take an age to dry out.

Today I have drilled the damp wall in 2 places from the inside to try to recover some insulation to test for soddenness - can't recover any insulation to test - just couldn't hook it out.

Maybe I need to remove a brick on the inside to gain access.

Is the mineral wool insulation they use water repellant or can it become sodden and retain the dampness for long periods.

What are the implications for other external walls in the property being that I've identified several areas externally where pointing is defficient.

I have nightmares of sodden CWI in various pointing deficient areas that would be verry difficult to fix without removal of the CWI.

Should mineral wool CW insulation actually have been used in this situation where external pointing was in some need.and would have been obvious at the time it was installed.

I know there are other possibilities for the damp in other areas but in THIS area the wall above is not damp.

How to fix it - thats the question.

Recommendations welcome.

TIA - It's me

Reply to
ItsMe
Loading thread data ...

It's an old house to have a cavity wall. I would start by getting some damp repellant solution from B&Q and slapping it on the outside brickwork to cover the whole of the damp area. Then get a dehumidifier on the inside. If it dries out and stays dry, it proves the damp is coming through the wall. I did this on a house with a similar problem which had solid walls. It is a quick job requiring no painting style accuracy, and it kept the house dry for several years. The permanant solution after that was to have the wall pointed.

Tony

Reply to
tonyjeffs

3-4 weeks isn't very long. I'd check it out again at the end of the summer
Reply to
stuart noble

Draw a pencil line around damp patch if it starts to dry ,it will be visible as it shrinks back. I would not suspect the insulation as the problem more likely a defective wall tie in this area. You have solved the problem of the damp source so time and good ventilation should do the rest. If you are selling thew house ,couple of coats of a stain block and repaint should solve immediate problem

Reply to
ALex

Use a dehumidifier and wait *a lot* longer. Think seasons not weeks.

Reply to
dom

After my basement flooded I was advised that it took a month per inch to dry out a solid wall, mine are three feet thick, so they could be damp for a while!

Reply to
Keith

It's not unusual for houses of that age in coastal/exposed locations to have cavity walls. In some sheltered areas solid walls were still common in the

30s. Age alone is not a good indicator.
Reply to
<me9

As others have said, it takes months to dry out brickwork.

It's unlikely that the insulation is wet because it's treated with a silicone waterproofing agent during manufacture, this however, doesn't stop water from tracking across the top of it if any voids are in the insulation, which is why all walls have to be filled right up to the top - if any voids /are/ left, the water can run down the inside of the exterior brickwork and on top of the insulation and into the interior brickwork, if the insulation goes all the way up without any voids, the water continues it's course down into the foundations.

If you really want to get to the bottom of it quickly and don't wish to wait, simply take down the section of interior brickwork and have a look inside - if there is a void, fill the area with cavity batt insulation and brick up with dry bricks and plaster over.

Reply to
Phil L

PP damp faq:

formatting link
short version is that once you've sorted the pointing and any other issues letting water in, its self fixing - but slow.

NT

Reply to
meow2222

Hi again,

Thanks to all respondents so far - especially NT and his/her period property forum link - very informative and recommended - lots for me to read on there. Links also to other informative sites on there.

I marked out the extent of the damp on the wall 3 -4 weeks ago following downpipe replacement and that's how I know it's not drying out though thanks for the tip.

I have obviously underestimated the time required to dry out damp internal brickwork. 3 - 4 weeks is not nearly long enough.

There is no doubt that this is a cavity wall - marked my drill shaft to a brick's depth and beyond that found a void to the external leaf - ie: the cavity.

Reassuring to know that mineral wool is is damp resistant though the question of voids in the wool has me a bit worried.

Other recommendations and links welcome.

Main reason for THIS post is to thank respondents. THANK YOU ALL.

Regards - Its me

I know I'm top posting but I always thing its easier to read the recent threads.

PP damp faq:

formatting link
short version is that once you've sorted the pointing and any other issues letting water in, its self fixing - but slow.

NT

Reply to
ItsMe

Seems to be just a series of edicts from your goodself

Reply to
stuart noble

I'm saying this ever so nicely - just in case you wondered.

There are no posts by me on those sites Stuart - I've only learned about them since posting this thread.

Don't know why you think posts there are from my 'goodself'. Or have I misunderstood your post.

May post there in future though - depends on the ongoing damp problem(s) I have.

I am not NT nor the DampMan in disguise. My degree of relative ignorance on drying times should make that obvious.

I'm requesting advice relating to my damp problem and other respondents shouldn't be dissuaded from replying based on Stuart's post.

I'm not into inflating a 'damp related expertise' ego that I don't have.

Just a thought

ItsMe

don't want other respondents to be 'put off'.

Reply to
ItsMe

No one said those posts were from you - he said they were from meow2222

Reply to
Phil L

FWIW the thread is a quick summary of the position of the main societies of expertise in the PP (period property) field. Yes the treatment of damp in PPs continues to be controversial in some respects. If you want to get into the subject deeper, each point made in that FAQ is discussed in much more depth on the pp forum, you only need ask and read. Some of course never do that - what's new.

NT

Reply to
meow2222

If anyone has similar problems here is a link to some very useful information.

formatting link
it was a pity she had the cavity walls insulated in this way.

Kingspan's ( never previously heard of them ) website also has lots of info regarding remedy.

ItsMe

Reply to
ItsMe

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.