damp internal walls??????

[techy21]

hi
I noticed to day that the inner walls of my house are moist.like not dripping wet but just moist.
its only in the beds bathroom and toilet.
they all in a row side of the house
its a single story double brick.
has cool and cosy roof insulation.
any ideas?????????
Thanks

[watchdog]

How old is the house and how high above floor level is it damp? How damp is it under the house where those walls are?

[allover]

Stumps, footings or slab?
Step 1, check for leaking pipes under and around house including drainage
Step 2, aggie pipes around circumference of house with a pit and drainage at lowest point, reappraise situation
p.s check stumps if timber

[gordon_s1942]

There are so many variables that cause moisture. My late Mother had an unflued Gas heater in one room and it caused moisture in 2 other rooms that wernt in much use.
The house was a timber framed Fibro clad probably 60 to 80 years old.
The moisture only appeared on the inside of walls that were external, not on any other wall in the house.
It was believed much of this was caused by the little Gas heater drying out the air and because the 2 walls affected were on the coldest side of the house, moisture collected on that wall.
I saw the results where underfloor ventilation was blocked off in an old Railway Station built around 1870.
With the building shut up and no ventilation, mold soon ran rampant.
It took a major effort to remove the mold and restore the ventilation under the floor so the building could be reused.
It seems air circulation plays an important part in keeping areas clean as well as leaks and other means of where moisture may collect.
That the heater was responsible was immediately apparent when it was turned off, the moisture disappeared after a day or 2.
My Mother was away for a few days meaning the Gas wasnt used and during that time despite the lousy weather, no moisture appeared on the walls.
Another thing we found was using a Fan in the room helped minimise the moisture somewhat as well.

[watchdog]

Stumps, footings or slab?
Step 1, check for leaking pipes under and around house including drainage
Step 2, aggie pipes around circumference of house with a pit and drainage at lowest point, reappraise situation
p.s check stumps if timber

Double brick house will be on strip footings

[gordon_s1942]

Double Brick, check to see that you have a damp course and that it isnt damaged or bushes, dirt has been piled up the wall above it, all vents low and high are clear.

I have seen older houses with double brick walls built on sandstone block foundations and no visible damp course.
I would be checking to see that the roof insulation hasnt covered the gap between the inner and outer wall which by doing so could alter the air flow.

[watchdog]

Having been through this exercise in depth I will pass on my findings.

1) The external wall of a cavity brick house is the weather -wall. There is NO dampcourse in this wall.
2) The interior wall has the dampcourse , usually made of lead.
3) The action of ground salts will cause this lead to decay.
4) Most houses using this form of construction have minimal sub-floor height, hence physical inspection is difficult if not impossible
5) There are only three ways for moisture to penetrate from the OUTSIDE - rising damp , falling damp & bridging damp
Rising Damp is due to dampcourse failure. Generally this dampness will not present more than a metre or so above ground level
Falling Damp is due to flashing failure and depending on the severity will present from the top of the wall & work downwards
Bridging Damp is due to the cavity being compromised. On older existing houses were the problem has suddenly appeared it is
often due to foreign objects being taken/dropped into the cavity by vermin causing a moisture bridge between inner & outer.
6) There are two ways to repair the dampcourse - replacement or chemical injection. Realistically the floor needs to be taken up for both.
7) Chemical injection to the outer wall is nothing but fraud. It achieves nothing and you will be wasting your money.

Condensation was a more recognised problem at time of construction than rising damp. To this extent there was ceiling ventilation incorporated in all these houses. Unfortunately the more recent know-it-alls fail to allow for this when they pull out the horsehair plaster ceilings & replace it with gyprock. Similarly groundwater evaporation has decreased due to the growth of hard surfaces in these areas. This has led to increased sub-floor moisture. If this is the problem you will need to get a bricky to knock out and form up ventilation cavities ON ALL 4 EXTERIOR WALLS. The best one of these solutions I have ever seen was two large (24") fans at two adjacent walls ducted to 2 brick x 1 brick cavities in the wall. (a bit like a split A/C outside unit) This gave good cross flow ventilation and was run from solar panels. Other solutions I have seen are passive ventilation in conjunction with a sump & pump to lower the water table on a local level.

As for the solution to my problem , I ended up selling the house. I got the opportunity to see it years later when it was again on the market and the owners had come up with a different approach to the problem. They had put in daddo boards on all the walls with the problem to hide the moist blistering plaster. It didn't look out of place given the house was built in 1910 and had extensive timberwork throughout.
7)

[gordon_s1942]

Watchdog, that is both an in depth and informative posting on this problem and not being in the building trade, I wasnt aware of how a damp course was applied on a double brick wall but it makes sense as to why it is done that way.
When I moved into this house over 50 years ago, due to the sloping block I found one corner of the house had been buried over a foot above the damp course and a metre long section of the wall plate along with the weatherboard had rotted out and had to be replaced.
I dug back the soil almost a metre and made sure I created a drain so that water coming down the slope to the house was turned away.
I now have a rudimentary brick path slightly sloped outward along there set one brick lower than the Damp course.
For this reason I dont like gardens right against the foundations nor bushes or shrubs actually in contact with the house walls and I wont have Ivy or any climbing plants growing up the walls, not even if their stood in pots because I have read they can 'Wick Up' moisture as well as provide a highway for all sorts of 'Nasties' into the house.

[techy21]

Thanks i look into with that info guy!!